1.
Steam turbine
–
A steam turbine is a device that extracts thermal energy from pressurized steam and uses it to do mechanical work on a rotating output shaft. Its modern manifestation was invented by Sir Charles Parsons in 1884, in 1551, Taqi al-Din in Ottoman Egypt described a steam turbine with the practical application of rotating a spit. Steam turbines were described by the Italian Giovanni Branca and John Wilkins in England. The devices described by Taqi al-Din and Wilkins are today known as steam jacks, in 1672 an impulse steam turbine driven car was designed by Ferdinand Verbiest. A more modern version of car was produced some time in the late 18th century by an unknown German mechanic. The modern steam turbine was invented in 1884 by Sir Charles Parsons, the invention of Parsons steam turbine made cheap and plentiful electricity possible and revolutionized marine transport and naval warfare. Parsons design was a reaction type and his patent was licensed and the turbine scaled-up shortly after by an American, George Westinghouse. The Parsons turbine also turned out to be easy to scale up. Parsons had the satisfaction of seeing his invention adopted for all major world power stations, a number of other variations of turbines have been developed that work effectively with steam. The de Laval turbine accelerated the steam to full speed before running it against a turbine blade, De Lavals impulse turbine is simpler, less expensive and does not need to be pressure-proof. It can operate with any pressure of steam, but is less efficient. He taught at the École des mines de Saint-Étienne for a decade until 1897, one of the founders of the modern theory of steam and gas turbines was Aurel Stodola, a Slovak physicist and engineer and professor at the Swiss Polytechnical Institute in Zurich. His work Die Dampfturbinen und ihre Aussichten als Wärmekraftmaschinen was published in Berlin in 1903, a further book Dampf und Gas-Turbinen was published in 1922. It was used in John Brown-engined merchant ships and warships, including liners, the present-day manufacturing industry for steam turbines is dominated by Chinese power equipment makers. Other manufacturers with minor market share include Bhel, Siemens, Alstom, GE, Doosan Škoda Power, Mitsubishi Heavy Industries, the consulting firm Frost & Sullivan projects that manufacturing of steam turbines will become more consolidated by 2020 as Chinese power manufacturers win increasing business outside of China. There are several classifications for modern steam turbines, Turbine blades are of two basic types, blades and nozzles. Blades move entirely due to the impact of steam on them and this results in a steam velocity drop and essentially no pressure drop as steam moves through the blades. A turbine composed of alternating with fixed nozzles is called an impulse turbine, Curtis turbine, Rateau turbine
Steam turbine
–
The rotor of a modern steam turbine used in a
power plant
Steam turbine
–
A 250 kW industrial steam turbine from 1910 (right) directly linked to a
generator (left).
Steam turbine
–
Diagram of an AEG marine steam turbine circa 1905
Steam turbine
–
A low-pressure steam turbine in a nuclear power plant. These turbines exhaust steam at a pressure below atmospheric.
2.
Latin
–
Latin is a classical language belonging to the Italic branch of the Indo-European languages. The Latin alphabet is derived from the Etruscan and Greek alphabets, Latin was originally spoken in Latium, in the Italian Peninsula. Through the power of the Roman Republic, it became the dominant language, Vulgar Latin developed into the Romance languages, such as Italian, Portuguese, Spanish, French, and Romanian. Latin, Italian and French have contributed many words to the English language, Latin and Ancient Greek roots are used in theology, biology, and medicine. By the late Roman Republic, Old Latin had been standardised into Classical Latin, Vulgar Latin was the colloquial form spoken during the same time and attested in inscriptions and the works of comic playwrights like Plautus and Terence. Late Latin is the language from the 3rd century. Later, Early Modern Latin and Modern Latin evolved, Latin was used as the language of international communication, scholarship, and science until well into the 18th century, when it began to be supplanted by vernaculars. Ecclesiastical Latin remains the language of the Holy See and the Roman Rite of the Catholic Church. Today, many students, scholars and members of the Catholic clergy speak Latin fluently and it is taught in primary, secondary and postsecondary educational institutions around the world. The language has been passed down through various forms, some inscriptions have been published in an internationally agreed, monumental, multivolume series, the Corpus Inscriptionum Latinarum. Authors and publishers vary, but the format is about the same, volumes detailing inscriptions with a critical apparatus stating the provenance, the reading and interpretation of these inscriptions is the subject matter of the field of epigraphy. The works of several hundred ancient authors who wrote in Latin have survived in whole or in part and they are in part the subject matter of the field of classics. The Cat in the Hat, and a book of fairy tales, additional resources include phrasebooks and resources for rendering everyday phrases and concepts into Latin, such as Meissners Latin Phrasebook. The Latin influence in English has been significant at all stages of its insular development. From the 16th to the 18th centuries, English writers cobbled together huge numbers of new words from Latin and Greek words, dubbed inkhorn terms, as if they had spilled from a pot of ink. Many of these words were used once by the author and then forgotten, many of the most common polysyllabic English words are of Latin origin through the medium of Old French. Romance words make respectively 59%, 20% and 14% of English, German and those figures can rise dramatically when only non-compound and non-derived words are included. Accordingly, Romance words make roughly 35% of the vocabulary of Dutch, Roman engineering had the same effect on scientific terminology as a whole
Latin
–
Latin inscription, in the
Colosseum
Latin
–
Julius Caesar 's
Commentarii de Bello Gallico is one of the most famous classical Latin texts of the Golden Age of Latin. The unvarnished, journalistic style of this
patrician general has long been taught as a model of the urbane Latin officially spoken and written in the floruit of the
Roman republic.
Latin
–
A multi-volume Latin dictionary in the
University Library of Graz
Latin
–
Latin and Ancient Greek Language - Culture - Linguistics at
Duke University in 2014.
3.
Vortex
–
In fluid dynamics, a vortex is a region in a fluid in which the flow rotates around an axis line, which may be straight or curved. The plural of vortex is either vortices or vortexes, vortices form in stirred fluids, and may be observed in phenomena such as smoke rings, whirlpools in the wake of boat, or the winds surrounding a tornado or dust devil. Vortices are a component of turbulent flow. The distribution of velocity, vorticity, as well as the concept of circulation are used to characterize vortices, in most vortices, the fluid flow velocity is greatest next to its axis and decreases in inverse proportion to the distance from the axis. Once formed, vortices can move, stretch, twist, a moving vortex carries with it some angular and linear momentum, energy, and mass. A key concept in the dynamics of vortices is the vorticity, conceptually, the vorticity could be observed by placing a tiny rough ball at the point in question, free to move with the fluid, and observing how it rotates about its center. The direction of the vorticity vector is defined to be the direction of the axis of rotation of this imaginary ball while its length is twice the angular velocity. The local rotation measured by the vorticity ω → must not be confused with the velocity vector of that portion of the fluid with respect to the external environment or to any fixed axis. In a vortex, in particular, ω → may be opposite to the angular velocity vector of the fluid relative to the vortexs axis. In theory, the u of the particles in a vortex may vary with the distance r from the axis in many ways. Ω → =, r → =, u → = Ω → × r → =, ω → = ∇ × u → = =2 Ω →. In this case the vorticity ω → is zero at any point not on that axis, Ω → =, r → =, u → = Ω → × r → =, ω → = ∇ × u → =0. In the absence of forces, a vortex usually evolves fairly quickly toward the irrotational flow pattern. Irrotational vortices are also called free vortices, for an irrotational vortex, the circulation is zero along any closed contour that does not enclose the vortex axis, and has a fixed value, Γ, for any contour that does enclose the axis once. The tangential component of the velocity is then u θ = Γ2 π r. The angular momentum per unit mass relative to the axis is therefore constant. However, the ideal irrotational vortex flow is not physically realizable, indeed, in real vortices there is always a core region surrounding the axis where the particle velocity stops increasing and then decreases to zero as r goes to zero. Within that region, the flow is no longer irrotational, the vorticity ω → becomes non-zero, the Rankine vortex is a model that assumes a rigid-body rotational flow where r is less than a fixed distance r0, and irrotational flow outside that core regions
Vortex
–
Vortex created by the passage of an
aircraft wing, revealed by colored smoke.
Vortex
–
Vortices evidenced by milk in a cup of coffee
Vortex
–
The
Crow Instability of a jet aeroplane's
contrail visually demonstrates the vortex created in the atmosphere (gas fluid medium) by the passage of the aircraft.
Vortex
–
The cloud vortex
Saturn's hexagon is at the north pole of the planet
Saturn.
4.
Turbulence
–
Turbulence or turbulent flow is a flow regime in fluid dynamics characterized by chaotic changes in pressure and flow velocity. It is in contrast to a flow regime, which occurs when a fluid flows in parallel layers. Turbulence is caused by kinetic energy in parts of a fluid flow. For this reason turbulence is easier to create in low viscosity fluids, in general terms, in turbulent flow, unsteady vortices appear of many sizes which interact with each other, consequently drag due to friction effects increases. This would increase the energy needed to pump fluid through a pipe, however this effect can also be exploited by such as aerodynamic spoilers on aircraft, which deliberately spoil the laminar flow to increase drag and reduce lift. The onset of turbulence can be predicted by a constant called the Reynolds number. However, turbulence has long resisted detailed physical analysis, and the interactions within turbulence creates a complex situation. Richard Feynman has described turbulence as the most important unsolved problem of classical physics, smoke rising from a cigarette is mostly turbulent flow. However, for the first few centimeters the flow is laminar, the smoke plume becomes turbulent as its Reynolds number increases, due to its flow velocity and characteristic length increasing. If the golf ball were smooth, the boundary layer flow over the front of the sphere would be laminar at typical conditions. However, the layer would separate early, as the pressure gradient switched from favorable to unfavorable. To prevent this happening, the surface is dimpled to perturb the boundary layer. This results in higher skin friction, but moves the point of boundary layer separation further along, resulting in form drag. The flow conditions in industrial equipment and machines. The external flow over all kind of such as cars, airplanes, ships. The motions of matter in stellar atmospheres, a jet exhausting from a nozzle into a quiescent fluid. As the flow emerges into this external fluid, shear layers originating at the lips of the nozzle are created and these layers separate the fast moving jet from the external fluid, and at a certain critical Reynolds number they become unstable and break down to turbulence. Biologically generated turbulence resulting from swimming animals affects ocean mixing, snow fences work by inducing turbulence in the wind, forcing it to drop much of its snow load near the fence
Turbulence
–
Flow visualization of a turbulent jet, made by
laser-induced fluorescence. The jet exhibits a wide range of length scales, an important characteristic of turbulent flows.
Turbulence
–
Laminar and turbulent water flow over the hull of a submarine
Turbulence
–
Turbulence in the
tip vortex from an
airplane wing
5.
Energy
–
In physics, energy is the property that must be transferred to an object in order to perform work on – or to heat – the object, and can be converted in form, but not created or destroyed. The SI unit of energy is the joule, which is the transferred to an object by the mechanical work of moving it a distance of 1 metre against a force of 1 newton. Mass and energy are closely related, for example, with a sensitive enough scale, one could measure an increase in mass after heating an object. Living organisms require available energy to stay alive, such as the humans get from food. Civilisation gets the energy it needs from energy resources such as fuels, nuclear fuel. The processes of Earths climate and ecosystem are driven by the radiant energy Earth receives from the sun, the total energy of a system can be subdivided and classified in various ways. It may also be convenient to distinguish gravitational energy, thermal energy, several types of energy, electric energy. Many of these overlap, for instance, thermal energy usually consists partly of kinetic. Some types of energy are a mix of both potential and kinetic energy. An example is energy which is the sum of kinetic. Whenever physical scientists discover that a phenomenon appears to violate the law of energy conservation. Heat and work are special cases in that they are not properties of systems, in general we cannot measure how much heat or work are present in an object, but rather only how much energy is transferred among objects in certain ways during the occurrence of a given process. Heat and work are measured as positive or negative depending on which side of the transfer we view them from, the distinctions between different kinds of energy is not always clear-cut. In contrast to the definition, energeia was a qualitative philosophical concept, broad enough to include ideas such as happiness. The modern analog of this property, kinetic energy, differs from vis viva only by a factor of two, in 1807, Thomas Young was possibly the first to use the term energy instead of vis viva, in its modern sense. Gustave-Gaspard Coriolis described kinetic energy in 1829 in its modern sense, the law of conservation of energy was also first postulated in the early 19th century, and applies to any isolated system. It was argued for years whether heat was a physical substance, dubbed the caloric, or merely a physical quantity. In 1845 James Prescott Joule discovered the link between mechanical work and the generation of heat and these developments led to the theory of conservation of energy, formalized largely by William Thomson as the field of thermodynamics
Energy
–
In a typical
lightning strike, 500
megajoules of
electric potential energy is converted into the same amount of energy in other forms, mostly
light energy,
sound energy and
thermal energy.
Energy
–
Thermal energy is energy of microscopic constituents of matter, which may include both
kinetic and
potential energy.
Energy
–
Thomas Young – the first to use the term "energy" in the modern sense.
Energy
–
A
Turbo generator transforms the energy of pressurised steam into electrical energy
6.
Fluid
–
In physics, a fluid is a substance that continually deforms under an applied shear stress. Fluids are a subset of the phases of matter and include liquids, gases, plasmas, fluids are substances that have zero shear modulus, or, in simpler terms, a fluid is a substance which cannot resist any shear force applied to it. Although the term includes both the liquid and gas phases, in common usage, fluid is often used as a synonym for liquid. For example, brake fluid is hydraulic oil and will not perform its required incompressible function if there is gas in it and this colloquial usage of the term is also common in medicine and in nutrition. Liquids form a surface while gases do not. The distinction between solids and fluid is not entirely obvious, the distinction is made by evaluating the viscosity of the substance. Silly Putty can be considered to behave like a solid or a fluid and it is best described as a viscoelastic fluid. There are many examples of substances proving difficult to classify, a particularly interesting one is pitch, as demonstrated in the pitch drop experiment currently running at the University of Queensland. Fluids display properties such as, not resisting deformation, or resisting it only slightly, and these properties are typically a function of their inability to support a shear stress in static equilibrium. Solids can be subjected to stresses, and to normal stresses—both compressive. In contrast, ideal fluids can only be subjected to normal, real fluids display viscosity and so are capable of being subjected to low levels of shear stress. In a solid, shear stress is a function of strain, a consequence of this behavior is Pascals law which describes the role of pressure in characterizing a fluids state. The study of fluids is fluid mechanics, which is subdivided into fluid dynamics, matter Liquid Gas Bird, Byron, Stewart, Warren, Lightfoot, Edward
Fluid
–
Continuum mechanics
7.
Work (physics)
–
In physics, a force is said to do work if, when acting, there is a displacement of the point of application in the direction of the force. For example, when a ball is held above the ground and then dropped, the SI unit of work is the joule. The SI unit of work is the joule, which is defined as the work expended by a force of one newton through a distance of one metre. The dimensionally equivalent newton-metre is sometimes used as the unit for work, but this can be confused with the unit newton-metre. Usage of N⋅m is discouraged by the SI authority, since it can lead to confusion as to whether the quantity expressed in newton metres is a torque measurement, or a measurement of energy. Non-SI units of work include the erg, the foot-pound, the foot-poundal, the hour, the litre-atmosphere. Due to work having the physical dimension as heat, occasionally measurement units typically reserved for heat or energy content, such as therm, BTU. The work done by a constant force of magnitude F on a point that moves a distance s in a line in the direction of the force is the product W = F s. For example, if a force of 10 newtons acts along a point that travels 2 meters and this is approximately the work done lifting a 1 kg weight from ground level to over a persons head against the force of gravity. Notice that the work is doubled either by lifting twice the weight the distance or by lifting the same weight twice the distance. Work is closely related to energy, the work-energy principle states that an increase in the kinetic energy of a rigid body is caused by an equal amount of positive work done on the body by the resultant force acting on that body. Conversely, a decrease in energy is caused by an equal amount of negative work done by the resultant force. From Newtons second law, it can be shown that work on a free, rigid body, is equal to the change in energy of the velocity and rotation of that body. The work of forces generated by a function is known as potential energy. These formulas demonstrate that work is the associated with the action of a force, so work subsequently possesses the physical dimensions. The work/energy principles discussed here are identical to Electric work/energy principles, constraint forces determine the movement of components in a system, constraining the object within a boundary. Constraint forces ensure the velocity in the direction of the constraint is zero and this only applies for a single particle system. For example, in an Atwood machine, the rope does work on each body, there are, however, cases where this is not true
Work (physics)
–
A
baseball pitcher does positive work on the ball by applying a force to it over the distance it moves while in his grip.
Work (physics)
–
A force of constant magnitude and perpendicular to the lever arm
Work (physics)
–
Gravity F = mg does work W = mgh along any descending path
Work (physics)
–
Lotus type 119B gravity racer at Lotus 60th celebration.
8.
Electric generator
–
In electricity generation, a generator is a device that converts mechanical energy to electrical energy for use in an external circuit. Sources of mechanical energy include steam turbines, gas turbines, water turbines, internal combustion engines, the first electromagnetic generator, the Faraday disk, was built in 1831 by British scientist Michael Faraday. Generators provide nearly all of the power for electric power grids, the reverse conversion of electrical energy into mechanical energy is done by an electric motor, and motors and generators have many similarities. Many motors can be driven to generate electricity and frequently make acceptable manual generators. Electromagnetic generators fall into one of two categories, dynamos and alternators. The magnetic field of the dynamo or alternator can be provided by either wire windings called field coils or permanent magnets, a generator using permanent magnets is sometimes called a magneto. Armature, The power-producing component of an electrical machine, in a generator, alternator, or dynamo the armature windings generate the electric current, which provides power to an external circuit. The armature can be on either the rotor or the stator, depending on the design, before the connection between magnetism and electricity was discovered, electrostatic generators were invented. They operated on electrostatic principles, by using moving electrically charged belts, plates, the charge was generated using either of two mechanisms, electrostatic induction or the triboelectric effect. Such generators generated very high voltage and low current and their only practical applications were to power early X-ray tubes, and later in some atomic particle accelerators. The operating principle of electromagnetic generators was discovered in the years of 1831–1832 by Michael Faraday, the principle later called Faradays law, is that an electromotive force is generated in an electrical conductor which encircles a varying magnetic flux. He also built the first electromagnetic generator, called the Faraday disk and it produced a small DC voltage. This design was inefficient, due to self-cancelling counterflows of current in regions of the disk that were not under the influence of the magnetic field. While current was induced directly underneath the magnet, the current would circulate backwards in regions that were outside the influence of the magnetic field and this counterflow limited the power output to the pickup wires, and induced waste heating of the copper disc. Later homopolar generators would solve this problem by using an array of magnets arranged around the perimeter to maintain a steady field effect in one current-flow direction. Another disadvantage was that the voltage was very low, due to the single current path through the magnetic flux. Experimenters found that using multiple turns of wire in a coil could produce higher, since the output voltage is proportional to the number of turns, generators could be easily designed to produce any desired voltage by varying the number of turns. Wire windings became a feature of all subsequent generator designs
Electric generator
–
U.S.
NRC image of a modern steam turbine generator (STG).
Electric generator
–
Early
Ganz Generator in
Zwevegem,
West Flanders,
Belgium
Electric generator
–
The
Faraday disk was the first electric generator. The horseshoe-shaped magnet (A) created a magnetic field through the disk (D). When the disk was turned, this induced an electric current radially outward from the center toward the rim. The current flowed out through the sliding spring contact m, through the external circuit, and back into the center of the disk through the axle.
Electric generator
–
This large belt-driven high-current
dynamo produced 310 amperes at 7 volts. Dynamos are no longer used due to the size and complexity of the
commutator needed for high power applications.
9.
Thrust
–
Thrust is a reaction force described quantitatively by Isaac Newtons second and third laws. When a system expels or accelerates mass in one direction, the mass will cause a force of equal magnitude. The force applied on a surface in a direction perpendicular or normal to the surface is called thrust. Force, and thus thrust, is measured in the International System of Units as the newton, in mechanical engineering, force orthogonal to the main load is referred to as thrust. A fixed-wing aircraft generates forward thrust when air is pushed in the direction opposite to flight. This can be done in several ways including by the blades of a propeller, or a rotating fan pushing air out from the back of a jet engine. The forward thrust is proportional to the mass of the airstream multiplied by the difference in velocity of the airstream, reverse thrust can be generated to aid braking after landing by reversing the pitch of variable-pitch propeller blades, or using a thrust reverser on a jet engine. Rotary wing aircraft and thrust vectoring V/STOL aircraft use engine thrust to support the weight of the aircraft, a motorboat generates thrust when the propellers are turned to accelerate water backwards. The resulting thrust pushes the boat in the direction from the combustion chamber through the rocket engine nozzle. For vertical launch of a rocket the initial thrust at liftoff must be more than the weight. Each of the three Space Shuttle Main Engines could produce a thrust of 1.8 MN, and each of the Space Shuttles two Solid Rocket Boosters 14.7 MN, together 29.4 MN. By contrast, the simplified Aid For EVA Rescue has 24 thrusters of 3.56 N each, in the air-breathing category, the AMT-USA AT-180 jet engine developed for radio-controlled aircraft produce 90 N of thrust. The GE90-115B engine fitted on the Boeing 777-300ER, recognized by the Guinness Book of World Records as the Worlds Most Powerful Commercial Jet Engine, has a thrust of 569 kN. The power needed to generate thrust and the force of the thrust can be related in a non-linear way and this helps to explain why moving through water is easier and why aircraft have much larger propellers than watercraft do. A very common question is how to contrast the thrust rating of a jet engine with the rating of a piston engine. Such comparison is difficult, as quantities are not equivalent. A piston engine does not move the aircraft by itself, so piston engines are rated by how much power they deliver to the propeller. Except for changes in temperature and air pressure, this quantity depends basically on the throttle setting, a jet engine has no propeller, so the propulsive power of a jet engine is determined from its thrust as follows
Thrust
–
Forces on an
aerofoil cross section
10.
Jet engines
–
A jet engine is a reaction engine discharging a fast-moving jet that generates thrust by jet propulsion. This broad definition includes airbreathing jet engines and non-airbreathing jet engines, in general, jet engines are combustion engines. In common parlance, the jet engine loosely refers to an internal combustion airbreathing jet engine. These typically feature an air compressor powered by a turbine. Jet aircraft use such engines for long-distance travel, early jet aircraft used turbojet engines which were relatively inefficient for subsonic flight. Modern subsonic jet aircraft usually use more complex high-bypass turbofan engines and these engines offer high speed and greater fuel efficiency than piston and propeller aeroengines over long distances. Jet engines date back to the invention of the aeolipile before the first century AD and this device directed steam power through two nozzles to cause a sphere to spin rapidly on its axis. So far as is known, it did not supply mechanical power, instead, it was seen as a curiosity. However, although powerful, at reasonable flight speeds rockets are very inefficient. The earliest attempts at airbreathing jet engines were hybrid designs in which a power source first compressed air. In one such system, called a thermojet by Secondo Campini but more commonly, motorjet, examples of this type of design were the Caproni Campini N.1, and the Japanese Tsu-11 engine intended to power Ohka kamikaze planes towards the end of World War II. None were entirely successful and the N.1 ended up being slower than the design with a traditional engine. If aircraft performance were ever to increase beyond such a barrier and this was the motivation behind the development of the gas turbine engine, commonly called a jet engine. The key to a jet engine was the gas turbine. The gas turbine was not an idea developed in the 1930s, the first gas turbine to successfully run self-sustaining was built in 1903 by Norwegian engineer Ægidius Elling. Limitations in design and practical engineering and metallurgy prevented such engines reaching manufacture, the main problems were safety, reliability, weight and, especially, sustained operation. The first patent for using a gas turbine to power an aircraft was filed in 1921 by Frenchman Maxime Guillaume and his engine was an axial-flow turbojet. Alan Arnold Griffith published An Aerodynamic Theory of Turbine Design in 1926 leading to work at the RAE
Jet engines
–
A
Pratt & Whitney F100 turbofan engine for the
F-15 Eagle being tested in the
hush house at
Florida Air National Guard base. The tunnel behind the engine muffles noise and allows exhaust to escape
Jet engines
–
U.S. Air Force
F-15E Strike Eagles
Jet engines
–
Simulation of a low-bypass turbofan's airflow.
Jet engines
–
Jet engine airflow during take-off.
11.
Turbomachinery
–
Turbomachinery, in mechanical engineering, describes machines that transfer energy between a rotor and a fluid, including both turbines and compressors. While a turbine transfers energy from a fluid to a rotor and these two types of machines are governed by the same basic relationships including Newtons second Law of Motion and Eulers pump and turbine equation for compressible fluids. Centrifugal pumps are also turbomachines that transfer energy from a rotor to a fluid, usually a liquid, while turbines, in general, the two kinds of turbomachines encountered in practice are open and closed turbomachines. Turbomachines are also categorized according to the type of flow, when the flow is parallel to the axis of rotation, they are called axial flow machines, and when flow is perpendicular to the axis of rotation, they are referred to as radial flow machines. There is also a category, called mixed flow machines. Of particular interest are applications which contain pumps, fans, compressors and these components are essential in almost all mechanical equipment systems, such as power and refrigeration cycles. Any devices that extracts energy from or imparts energy to a moving stream of fluid can be called a Turbomachine. Turbines, compressors and fans are all members of family of machines. In contrast to positive displacement machines, the majority of run at comparatively higher speeds without any mechanical problems. Turbomachines can be categorized on the basis of the direction of energy conversion, produce power by expanding fluid to a lower pressure or head. The radial component of the velocity is negligible. Since there is no change in the direction of the fluid, a Kaplan turbine is an example of an axial flow turbine. In the figure, U = Blade velocity, Vf = Flow velocity, V = Absolute velocity, Vr = Relative velocity, Vw = Tangential or Whirl component of velocity. Radial flow turbomachines - When the path of the through-flow is wholly or mainly in a perpendicular to the rotation axis. Therefore, the change of radius between the entry and the exit is finite, a Radial turbomachine can be inward or outward flow type depending on the purpose that needs to be served. Outward flow type increases the level of the fluid and vice versa. Due to continuous change in direction, several stages are generally not used. A centrifugal pump is an example of a radial flow turbine, in the figure, U = Blade velocity, Vf = Flow velocity, V = Absolute velocity, Vr = Relative velocity, Vw = Tangential or Whirl component of velocity
Turbomachinery
–
Mounting of a
steam turbine produced by
Siemens, Germany
Turbomachinery
–
A steam turbine from
MAN SE subdidiary MAN Turbo
Turbomachinery
–
Pelton wheel being installed into
Walchensee Hydroelectric Power Station.
12.
Turbine blade
–
A turbine blade is the individual component which makes up the turbine section of a gas turbine or steam turbine. The blades are responsible for extracting energy from the high temperature, the turbine blades are often the limiting component of gas turbines. Blade fatigue is a source of failure in steam turbines. Fatigue is caused by the stress induced by vibration and resonance within the range of machinery. To protect blades from these high stresses, friction dampers are used. Blades of wind turbines and water turbines are designed to operate in different conditions, in a gas turbine engine, a single turbine section is made up of a disk or hub that holds many turbine blades. That turbine section is connected to a compressor section via a shaft, Air is compressed, raising the pressure and temperature, through the compressor stages of the engine. The temperature is greatly increased by combustion of fuel inside the combustor. The high-temperature and high-pressure exhaust gases pass through the turbine stages. The turbine stages extract energy from this flow, lowering the pressure and temperature of the air and this process is very similar to how an axial compressor works, only in reverse. The number of turbine stages varies in different types of engines, the number of turbine stages can have a great effect on how the turbine blades are designed for each stage. Many gas turbine engines are twin-spool designs, meaning there is a high-pressure spool. Other gas turbines use three spools, adding an intermediate-pressure spool between the high- and low-pressure spool, the high-pressure turbine is exposed to the hottest, highest-pressure air, and the low-pressure turbine is subjected to cooler, lower-pressure air. Under these severe operating conditions inside the gas and steam turbines, the blades face high temperature, high stresses, turbine blades are subjected to very strenuous environments inside a gas turbine. They face high temperatures, high stresses, and an environment of high vibration. All three of these factors can lead to failures, potentially destroying the engine, therefore turbine blades are carefully designed to resist these conditions. Turbine blades are subjected to stress from centrifugal force and fluid forces that can cause fracture, yielding, additionally, the first stage of a modern turbine faces temperatures around 2,500 °F, up from temperatures around 1,500 °F in early gas turbines. Modern military jet engines, like the Snecma M88, can see temperatures of 2,900 °F
Turbine blade
–
Turbine blade from a
Turbo-Union RB199 jet engine.
Turbine blade
–
A turbine blade with thermal barrier coating.
Turbine blade
–
Laser-drilled holes permit film cooling in this first-stage
V2500 nozzle guide vane
Turbine blade
–
Blade cooling by convection
13.
Windmill
–
A windmill is a mill that converts the energy of wind into rotational energy by means of vanes called sails or blades. Centuries ago, windmills usually were used to mill grain, pump water, thus they often were gristmills, windpumps, or both. The majority of modern windmills take the form of wind turbines used to generate electricity, the windwheel of the Greek engineer Heron of Alexandria in the first century is the earliest known instance of using a wind-driven wheel to power a machine. Another early example of a wheel was the prayer wheel. It has been claimed that the Babylonian emperor Hammurabi planned to use wind power for his ambitious project in the seventeenth century BCE. The first practical windmills had sails that rotated in a horizontal plane, according to Ahmad Y. al-Hassan, these panemone windmills were invented in eastern Persia as recorded by the Persian geographer Estakhri in the ninth century. The authenticity of an anecdote of a windmill involving the second caliph Umar is questioned on the grounds that it appears in a tenth-century document. Made of six to 12 sails covered in reed matting or cloth material, these windmills were used to grind grain or draw up water, Windmills were in widespread use across the Middle East and Central Asia, and later spread to China and India from there. A similar type of windmill with rectangular blades, used for irrigation, can also be found in thirteenth-century China. Horizontal windmills were built, in numbers, in Europe during the 18th and nineteenth centuries, for example Fowlers Mill at Battersea in London. Due to a lack of evidence, debate occurs among historians as to whether or not Middle Eastern horizontal windmills triggered the development of European windmills. In northwestern Europe, the horizontal-axis or vertical windmill is believed to date from the last quarter of the century in the triangle of northern France, eastern England. The earliest certain reference to a windmill in Europe dates from 1185, a number of earlier, but less certainly dated, twelfth-century European sources referring to windmills have also been found. These earliest mills were used to grind cereals, the evidence at present is that the earliest type of European windmill was the post mill, so named because of the large upright post on which the mills main structure is balanced. The body contains all the milling machinery, the first post mills were of the sunken type, where the post was buried in an earth mound to support it. Later, a wooden support was developed called the trestle and this was often covered over or surrounded by a roundhouse to protect the trestle from the weather and to provide storage space. This type of windmill was the most common in Europe until the nineteenth century, in a hollow-post mill, the post on which the body is mounted is hollowed out, to accommodate the drive shaft. This makes it possible to drive machinery below or outside the body still being able to rotate the body into the wind
Windmill
–
The
smock mill Goliath in front of the
wind farm Growind in
Eemshaven in the
Netherlands
Windmill
–
A
tower mill in
Dalian, China
Windmill
–
Heron 's wind-powered
organ
Windmill
–
Hooper's Mill, Margate, Kent, an eighteenth-century European horizontal windmill
14.
Waterwheel
–
A water wheel is a machine for converting the energy of flowing or falling water into useful forms of power, often in a watermill. A water wheel consists of a wheel, with a number of blades or buckets arranged on the outside rim forming the driving surface. Most commonly, the wheel is mounted vertically on a horizontal axle, vertical wheels can transmit power either through the axle or via a ring gear and typically drive belts or gears, horizontal wheels usually directly drive their load. Water wheels were still in use well into the 20th century. Uses included milling flour in gristmills, grinding wood into pulp for papermaking, hammering wrought iron, machining, some water wheels are fed by water from a mill pond, which is formed when a flowing stream is dammed. A channel for the water flowing to or from a wheel is called a mill race. The race bringing water from the pond to the water wheel is a headrace. In the mid to late 18th century John Smeatons scientific investigation of the water led to significant increases in efficiency supplying much needed power for the Industrial Revolution. Water wheels began being displaced by the smaller, less expensive and more efficient turbine, developed by Benoît Fourneyron, turbines are capable of handling high heads, or elevations, that exceed the capability of practical-sized waterwheels. The main difficulty of water wheels is their dependence on flowing water, modern hydroelectric dams can be viewed as the descendants of the water wheel, as they too take advantage of the movement of water downhill. The two main functions of water wheels were historically water-lifting for irrigation purposes and as a power source, when used for water-lifting power can be supplied by either human or animal force or by the water current itself. Water wheels come in two designs, either a vertical or a horizontal axle. The latter type can be subdivided, depending on where the hits the wheel. Engineers of the Hellenistic era Mediterranean region are credited with the development of the water wheel, Mediterranean engineers of the Hellenistic and Roman periods were also the first to use it for both irrigation and as a power source. The technological breakthrough occurred in the advanced and scientifically minded Hellenistic period between the 3rd and 1st centuries BCE. This is seen as an evolution of the paddle-driven water-lifting wheels that had appeared in ancient Egypt by the 4th century BCE. According to John Peter Oleson, both the wheel and the hydraulic Noria appeared in Egypt by the 4th century BCE. This is supported by finds at Faiyum, where the oldest archeological evidence of a water-wheel has been found
Waterwheel
–
An overshot waterwheel standing 42 ft (13 m) high powers the Old Mill at
Berry College in
Rome, Georgia, USA
Waterwheel
–
Water wheel powering a
mine hoist in
De re metallica (1566)
Waterwheel
–
Sequence of wheels found in
Rio Tinto mines, southwestern Spain
Waterwheel
–
Reconstruction of
Vitruvius ' undershot-wheeled watermill
15.
Gas turbine
–
A gas turbine, also called a combustion turbine, is a type of internal combustion engine. It has an upstream rotating compressor coupled to a turbine. The basic operation of the gas turbine is similar to that of the power plant except that the working fluid is air instead of water. Fresh atmospheric air flows through a compressor that brings it to higher pressure, energy is then added by spraying fuel into the air and igniting it so the combustion generates a high-temperature flow. This high-temperature high-pressure gas enters a turbine, where it expands down to the exhaust pressure, the turbine shaft work is used to drive the compressor and other devices such as an electric generator that may be coupled to the shaft. The energy that is not used for shaft work comes out in the exhaust gases, the purpose of the gas turbine determines the design so that the most desirable energy form is maximized. Gas turbines are used to power aircraft, trains, ships, electrical generators,50, Heros Engine — Apparently, Heros steam engine was taken to be no more than a toy, and thus its full potential not realized for centuries. 1000, The Trotting Horse Lamp was used by the Chinese at lantern fairs as early as the Northern Song dynasty. When the lamp is lit, the heated airflow rises and drives an impeller with horse-riding figures attached on it,1629, Jets of steam rotated an impulse turbine that then drove a working stamping mill by means of a bevel gear, developed by Giovanni Branca. 1678, Ferdinand Verbiest built a model carriage relying on a jet for power. 1791, A patent was given to John Barber, an Englishman and his invention had most of the elements present in the modern day gas turbines. The turbine was designed to power a horseless carriage,1861, British patent no.1633 was granted to Marc Antoine Francois Mennons for a Caloric engine. The patent shows that it was a gas turbine and the show it applied to a locomotive. Also named in the patent was Nicolas de Telescheff, a Russian aviation pioneer,1872, A gas turbine engine was designed by Franz Stolze, but the engine never ran under its own power. 1894, Sir Charles Parsons patented the idea of propelling a ship with a turbine, and built a demonstration vessel. This principle of propulsion is still of some use,1895, Three 4-ton 100 kW Parsons radial flow generators were installed in Cambridge Power Station, and used to power the first electric street lighting scheme in the city. 1899, Charles Gordon Curtis patented the first gas engine in the USA. 1900, Sanford Alexander Moss submitted a thesis on gas turbines, in 1903, Moss became an engineer for General Electrics Steam Turbine Department in Lynn, Massachusetts
Gas turbine
–
Sketch of John Barber's gas turbine, from his patent
Gas turbine
–
Examples of gas turbine configurations: (1)
turbojet, (2)
turboprop, (3)
turboshaft (electric generator), (4) high-bypass
turbofan, (5) low-bypass
afterburning turbofan.
Gas turbine
–
A typical axial-flow gas turbine turbojet, the
J85, sectioned for display. Flow is left to right, multistage compressor on left, combustion chambers center, two-stage turbine on right.
Gas turbine
–
GE H series power generation gas turbine: in
combined cycle configuration, this 480-
megawatt unit has a rated
thermal efficiency of 60%.
16.
Water turbine
–
A water turbine is a rotary machine that converts kinetic energy and potential energy of water into mechanical work. Water turbines were developed in the 19th century and were used for industrial power prior to electrical grids. Now they are used for electric power generation. Water turbines are mostly found in dams to generate power from water kinetic energy. Water wheels have been used for hundreds of years for industrial power and their main shortcoming is size, which limits the flow rate and head that can be harnessed. The migration from water wheels to modern turbines took about one hundred years, development occurred during the Industrial revolution, using scientific principles and methods. They also made use of new materials and manufacturing methods developed at the time. The word turbine was introduced by the French engineer Claude Burdin in the early 19th century and is derived from the Greek word τύρβη for whirling or a vortex. The main difference between early water turbines and water wheels is a component of the water which passes energy to a spinning rotor. This additional component of motion allowed the turbine to be smaller than a wheel of the same power. They could process more water by spinning faster and could harness much greater heads, the earliest known water turbines date to the Roman Empire. Two helix-turbine mill sites of almost identical design were found at Chemtou and Testour, modern-day Tunisia, the horizontal water wheel with angled blades was installed at the bottom of a water-filled, circular shaft. The water from the mill-race entered the pit tangentially, creating a water column which made the fully submerged wheel act like a true turbine. Fausto Veranzio in his book Machinae Novae described a vertical axis mill with a similar to that of a Francis turbine. Johann Segner developed a water turbine in the mid-18th century in Kingdom of Hungary. It had a horizontal axis and was a precursor to modern water turbines and it is a very simple machine that is still produced today for use in small hydro sites. Segner worked with Euler on some of the mathematical theories of turbine design. In the 18th century, a Dr. Barker invented a similar reaction hydraulic turbine that became popular as a lecture-hall demonstration
Water turbine
–
The runner of the small water turbine.
Water turbine
–
Kaplan turbine and
electrical generator cut-away view.
Water turbine
–
The construction of a
Ganz water Turbo Generator in Budapest in 1886
Water turbine
–
Roman turbine mill at
Chemtou,
Tunisia. The tangential water inflow of the millrace made the submerged horizontal wheel in the shaft turn like a true turbine.
17.
Charles Algernon Parsons
–
Sir Charles Algernon Parsons, OM, KCB, FRS, the son of a member of the Irish peerage, was an Anglo-Irish engineer, best known for his invention of the compound steam turbine. He worked as an engineer on dynamo and turbine design, and power generation and he also developed optical equipment, for searchlights and telescopes. Parsons was born in London into an Anglo-Irish family, youngest son of the famous astronomer William Parsons, the family seat is Birr Castle, County Offaly, Ireland, and the town of Birr was called Parsonstown, after the family, from 1620 to 1899. One of them later became, as Sir Robert Ball, Astronomer Royal for Ireland, Parsons then read mathematics at Trinity College, Dublin and St. Johns College, Cambridge, graduating from the latter in 1877 with a first-class honours degree. He developed an engine there in 1884 and immediately utilized the new engine to drive an electrical generator. In 1889, he founded C. A. Parsons and Company in Newcastle to produce turbo generators to his design, in the same year he set up the Newcastle and District Electric Lighting Company. In 1890, DisCo opened Forth Banks Power Station, the first power station in the world to generate electricity using turbo generators, in 1894 he regained certain patent rights from Clarke Chapman. Parsons was also interested in applications and founded the Parsons Marine Steam Turbine Company in Newcastle. The Turbinia moved at 34 knots, the fastest Royal Navy ships using other technologies reached 27 knots. Part of the improvement was attributable to the slender hull of the Turbinia. Today, Turbinia is housed in a gallery at the Discovery Museum. He was elected a Fellow of the Royal Society in June 1898 and received their Rumford Medal in 1902, their Copley Medal in 1928 and he was the president of the British Association for 1916–1919. He was knighted in 1911 and made a member of the Order of Merit in 1927, the Parsons turbine company survives in the Heaton area of Newcastle and is now part of Siemens, a German conglomerate. In 1925 Charles Parsons acquired the Grubb Telescope Company and renamed it Grubb Parsons and that company survived in the Newcastle area until 1985. Parsons was also known for inventing the Auxetophone, a compressed air gramophone. In 1883 Parsons married Katharine Bethell, the daughter of William F. Bethell and they had two children, Rachel Mary Parsons, and Algernon George Parsons, who was killed in action during World War I in 1918, aged 31. Charles Algernon Parsons died on 11 February 1931, on board the steamship Duchess of Richmond while on a cruise with his wife, the cause of death was given as neuritis. A memorial service was held at Westminster Abbey on 3 March 1931, Parsons was buried in the parish church of St Bartholomews in Kirkwhelpington in Northumberland
Charles Algernon Parsons
–
The Honourable Sir Charles Algernon Parsons
OM KCB FRS
Charles Algernon Parsons
–
Parsons' first 1MW turbogenerator built for
Elberfeld, Germany in 1899. It produced single phase electricity at 4kV.
Charles Algernon Parsons
–
Dreadnought. In 1906, it was the first modern battleship and was fastest in the world due to Parsons' steam turbines.
18.
Gustaf de Laval
–
Karl Gustaf Patrik de Laval was a Swedish engineer and inventor who made important contributions to the design of steam turbines and dairy machinery. Gustaf de Laval was born at Orsa in Dalarna in the Swedish de Laval Huguenot family and he enrolled at the Institute of Technology in Stockholm in 1863, receiving a degree in mechanical engineering in 1866, after which he matriculated at Uppsala University in 1867. He was then employed by the Swedish mining company, Stora Kopparberg, from there he returned to Uppsala University and completed his doctorate in 1872. He was further employed in Kloster Iron works in Husby parish, Gustaf de Laval was a member of the Royal Swedish Academy of Sciences from 1886. He was a engineer and businessman. He also held office, being elected to Swedish parliament, from 1888 to 1890. De Laval died in Stockholm in 1913 at the age of 67, in 1882 he introduced his concept of an impulse steam turbine and in 1887 built a small steam turbine to demonstrate that such devices could be constructed on that scale. In 1890 Laval developed a nozzle to increase the steam jet to supersonic speed, working off the energy of the steam. The nozzle, now known as a de Laval nozzle, is used in rocket engine nozzles. De Laval turbines can run at up to 30,000 rpm, the turbine wheel was mounted on a long flexible shaft, its two bearings spaced far apart on either side. The higher speed of the turbine demanded that he also design new approaches to reduction gearing, after trying several methods, he concluded that a centrifugal separator was the most affordable and effective method. He developed several types, and their success established the centrifugal separator as a device in a variety of applications. De Laval also made important contributions to the industry, including the first centrifugal milk-cream separator and early milking machines. It was not until after his death, however, that the company he founded marketed the first commercially practical milking machine, in 1918. Together with Oscar Lamm, de Laval founded the company Alfa Laval in 1883, in 1991, Alfa Laval Agri, a company producing dairy and farming machinery was split from Alfa Laval when it was bought by the Tetra Pak Group. When Alfa Laval was sold, Alfa Laval Agri remained a part of the Tetra Pak group and was renamed DeLaval and he is interred at Norra begravningsplatsen in Stockholm, Sweden. History of the combustion engine Alfa Laval - Official site DeLaval - Official site DeLaval - Unofficial site
Gustaf de Laval
–
Gustaf de Laval 1875
Gustaf de Laval
–
de Laval's forge in Kloster
Gustaf de Laval
–
Impulse Turbine by Gustaf de Laval. Built in Sweden, 1888. Deutsches Museum, Munich.
Gustaf de Laval
–
A unique submarine invented by Gustaf de Laval
19.
Degree of reaction
–
Degree of reaction is an important factor in designing the blades of a turbine, compressors, pumps and other turbo-machinery. It also tells about the efficiency of machine and is used for selection of a machine for a required purpose. Various definitions exist in terms of enthalpies, pressures or flow geometry of the device, in pumps, degree of reaction deals in static and dynamic head. Degree of reaction is defined as the fraction of energy transfer by change in head to the total energy transfer in the rotor i. e. R = Static pressure rise in rotor Total pressure rise in stage. Most turbo machines are efficient to a degree and can be approximated to undergo isentropic process in the stage. Hence from T d s = d h − d p, and 2 to 3ss is the isentropic process from rotor inlet at 2 to rotor outlet at 3. Due to the change in there is a corresponding pressure change. In practice is substituted as ϕ and as tan β m giving R = ϕ tan β m. The degree of reaction now depends only on ϕ and tan β m which again depend on geometrical parameters β3 and β2 i. e. the vane angles of stator outlet and rotor outlet. The Figure 3 alongside shows the variation of total-to-static efficiency at different blade loading coefficient with the degree of reaction. The governing equation is written as R =1 + Δ W2 U2 − C y 2 U where Δ W2 U2 is the stage loading factor. The diagram shows the optimization of total - to - static efficiency at a given stage loading factor and it is evident from the diagram that for a fixed stage loading factor that there is a relatively small change in total-to-static efficiency for a wide range of designs. The degree of reaction contributes to the efficiency and thus used as a design parameter. Stages having 50% degree of reaction are used where the drop is equally shared by the stator. This reduces the tendency of boundary layer separation from the blade surface avoiding large stagnation pressure losses, if R= 1⁄2 then from the relation of degree of reaction, |C| α2 = β3 and the velocity triangle is symmetric. The stage enthalpy gets equally distributed in the stage, in addition the whirl components at are also same at the inlet of rotor and diffuser. Stage having reaction less than half suggest that pressure drop or enthalpy drop in the rotor is less than the drop in the stator for the turbine. The same follows for a pump or compressor as shown in Figure 6, therefore the stator has a larger contribution to the total work extracted or work done
Degree of reaction
–
Figure 1. Enthalpy vs. Entropy diagram for stage flow in turbine
Degree of reaction
–
Figure 2. Velocity Triangle for fluid flow in turbine
Degree of reaction
–
Figure 3. Influence of reaction on total-to-static efficiency with fixed value of stage loading factor
Degree of reaction
–
Figure 4. Velocity triangle for Degree of Reaction = 1/2 in a turbine
20.
French Academy of Sciences
–
The French Academy of Sciences is a learned society, founded in 1666 by Louis XIV at the suggestion of Jean-Baptiste Colbert, to encourage and protect the spirit of French scientific research. It was at the forefront of developments in Europe in the 17th and 18th centuries. Currently headed by Sébastien Candel, it is one of the five Academies of the Institut de France, the Academy of Sciences makes its origin to Colberts plan to create a general academy. He chose a group of scholars who met on 22 December 1666 in the Kings library. The first 30 years of the Academys existence were relatively informal, in contrast to its British counterpart, the Academy was founded as an organ of government. The Academy was expected to remain apolitical, and to avoid discussion of religious, on 20 January 1699, Louis XIV gave the Company its first rules. The Academy received the name of Royal Academy of Sciences and was installed in the Louvre in Paris, following this reform, the Academy began publishing a volume each year with information on all the work done by its members and obituaries for members who had died. This reform also codified the method by which members of the Academy could receive pensions for their work, on 8 August 1793, the National Convention abolished all the academies. Almost all the old members of the previously abolished Académie were formally re-elected, among the exceptions was Dominique, comte de Cassini, who refused to take his seat. In 1816, the again renamed Royal Academy of Sciences became autonomous, while forming part of the Institute of France, in the Second Republic, the name returned to Académie des sciences. During this period, the Academy was funded by and accountable to the Ministry of Public Instruction, the Academy came to control French patent laws in the course of the eighteenth century, acting as the liaison of artisans knowledge to the public domain. As a result, academicians dominated technological activities in France, the Academy proceedings were published under the name Comptes rendus de lAcadémie des sciences. The Comptes rendus is now a series with seven titles. The publications can be found on site of the French National Library, in 1818 the French Academy of Sciences launched a competition to explain the properties of light. The civil engineer Augustin-Jean Fresnel entered this competition by submitting a new theory of light. Siméon Denis Poisson, one of the members of the judging committee, being a supporter of the particle-theory of light, he looked for a way to disprove it. The Poisson spot is not easily observed in every-day situations, so it was natural for Poisson to interpret it as an absurd result. However, the head of the committee, Dominique-François-Jean Arago, and he molded a 2-mm metallic disk to a glass plate with wax
French Academy of Sciences
–
A heroic depiction of the activities of the Academy from 1698
French Academy of Sciences
–
Colbert Presenting the Members of the Royal Academy of Sciences to Louis XIV in 1667
French Academy of Sciences
–
The
Institut de France in Paris where the Academy is housed
21.
Safety lamp
–
Until the development of effective electric lamps in the early 1900s miners used flame lamps to provide illumination. Flame safety lamps have been replaced in mining with sealed explosion-proof electric lights, Miners have traditionally referred to the various gases encountered during mining as damps, from the Middle Low German word dampf. Damps are variable mixtures and are historic terms, firedamp - Naturally occurring flammable mixtures, principally methane. Blackdamp or Chokedamp - Nitrogen and carbon dioxide with no oxygen, Formed by complete combustion of firedamp or occurring naturally. Coal in contact with air will slowly and, if unused workings are not ventilated. Also referred to as air in some 19th-century papers. Whitedamp - Formed by the combustion of coal, or firedamp. The mixture may contain significant amounts of carbon monoxide, which is toxic, stinkdamp - Naturally occurring hydrogen sulphide and other gases. The hydrogen sulphide is highly toxic, but easily detected by smell, the other gases with it may be firedamp or blackdamp. Afterdamp - The gas from an explosion of firedamp or coal dust, contains varying proportions of blackdamp and whitedamp and is therefore suffocating, toxic, or explosive, or any combination of these. Afterdamp may be a bigger killer following an explosion than the explosion itself, before the invention of safety lamps, miners used candles with open flames. This gave rise to frequent explosions, for example, at one colliery in the north east of England,10 miners were killed in 1806,12 in 1809. In 1812,90 men and boys were suffocated or burnt to death in the Felling Pit near Gateshead and 22 in the following year, wood 1853 describes the testing of a mine for firedamp. A candle is prepared by being trimmed and excess fat removed and it is held at arms length at floor level in one hand, the other hand shielding out all except the tip of the flame. As the candle is raised the tip is observed and if unchanged the atmosphere is safe, if however the tip turns bluish-gray increasing in height to a thin extended point becoming a deeper blue, then firedamp is present. Upon detecting firedamp the candle is lowered and arrangements made for the ventilating of the area or the firing of the firedamp after the end of a shift. A man, known as a fireman, penitent or monk edged forward with a candle on the end of a stick. He kept his head down to allow the explosion to pass over him, as can be imagined this procedure did not always preserve the life of the man so employed
Safety lamp
–
Modern flame safety lamp used in mines, manufactured by Koehler
Safety lamp
–
Spedding mill at the German mining museum, Bochum, Northrhine-Westfalia, Germany
Safety lamp
–
Early form of Stephenson lamp shown with a Davy lamp on the left
Safety lamp
–
Mueseler lamp (on the left) and a derivative of the Geordie
22.
Stator
–
The stator is the stationary part of a rotary system, found in electric generators, electric motors, sirens, or biological rotors. The main use of a stator is to keep the field aligned, the first DC generators and DC motors put the field coils on the stator, and the power generation or motive reaction coils on the rotor. This is necessary because a moving power switch known as the commutator is needed to keep the field correctly aligned across the spinning rotor. The commutator must become larger and more robust as the current increases, the stator of these devices may be either a permanent magnet or an electromagnet. Where the stator is an electromagnet, the coil which energizes it is known as the coil or field winding. The coil can be either iron core or aluminum, to reduce loading losses in motors, manufacturers invariably use copper as the conducting material in windings. Aluminum, because of its electrical conductivity, may be an alternate material in fractional horsepower motors. An AC alternator is able to power across multiple high-current power generation coils connected in parallel. Placing the field coils on the rotor allows for a slip ring mechanism to transfer high-voltage. It consists of a steel frame enclosing a hollow cylindrical core, the laminations are to reduce hysteresis and eddy current losses. In a turbine, the element contains blades or ports used to redirect the flow of fluid. Such devices include the steam turbine and the torque converter, in a mechanical siren, the stator contains one or more rows of holes that admit air into the rotor, by controlling the flow of air through the holes, the sound of the siren can be altered
Stator
–
Rotor (lower left) and stator (upper right) of an electric motor
Stator
–
Stator of a 3-phase AC-motor
Stator
–
Stator of a brushless DC motor from computer cooler fan.
Stator
–
Stator winding of a generator at a
hydroelectric power station.
23.
Potential energy
–
In physics, potential energy is energy possessed by a body by virtue of its position relative to others, stresses within itself, electric charge, and other factors. The unit for energy in the International System of Units is the joule, the term potential energy was introduced by the 19th century Scottish engineer and physicist William Rankine, although it has links to Greek philosopher Aristotles concept of potentiality. Potential energy is associated with forces that act on a body in a way that the work done by these forces on the body depends only on the initial and final positions of the body in space. These forces, that are called potential forces, can be represented at every point in space by vectors expressed as gradients of a scalar function called potential. Potential energy is the energy of an object. It is the energy by virtue of a position relative to other objects. Potential energy is associated with restoring forces such as a spring or the force of gravity. The action of stretching the spring or lifting the mass is performed by a force that works against the force field of the potential. This work is stored in the field, which is said to be stored as potential energy. If the external force is removed the field acts on the body to perform the work as it moves the body back to the initial position. Suppose a ball which mass is m, and it is in h position in height, if the acceleration of free fall is g, the weight of the ball is mg. There are various types of energy, each associated with a particular type of force. Chemical potential energy, such as the energy stored in fossil fuels, is the work of the Coulomb force during rearrangement of mutual positions of electrons and nuclei in atoms and molecules. Thermal energy usually has two components, the energy of random motions of particles and the potential energy of their mutual positions. Forces derivable from a potential are also called conservative forces, the work done by a conservative force is W = − Δ U where Δ U is the change in the potential energy associated with the force. The negative sign provides the convention that work done against a force field increases potential energy, common notations for potential energy are U, V, also Ep. Potential energy is closely linked with forces, in this case, the force can be defined as the negative of the vector gradient of the potential field. If the work for a force is independent of the path, then the work done by the force is evaluated at the start
Potential energy
–
In the case of a
bow and arrow, when the archer does work on the bow, drawing the string back, some of the chemical energy of the archer's body is transformed into elastic potential-energy in the bent limbs of the bow. When the string is released, the force between the string and the arrow does work on the arrow. Thus, the potential energy in the bow limbs is transformed into the
kinetic energy of the arrow as it takes flight.
Potential energy
–
A
trebuchet uses the gravitational potential energy of the
counterweight to throw projectiles over two hundred meters
Potential energy
–
Springs are used for storing
elastic potential energy
Potential energy
–
Archery is one of humankind's oldest applications of elastic potential energy
24.
Head (hydraulic)
–
Hydraulic head or piezometric head is a specific measurement of liquid pressure above a geodetic datum. It is usually measured as a surface elevation, expressed in units of length. In an aquifer, it can be calculated from the depth to water in a piezometric well, hydraulic head can similarly be measured in a column of water using a standpipe piezometer by measuring the height of the water surface in the tube relative to a common datum. The hydraulic head can be used to determine a hydraulic gradient between two or more points, in fluid dynamics, head is a concept that relates the energy in an incompressible fluid to the height of an equivalent static column of that fluid. Head is expressed in units of such as meters or feet. The static head of a pump is the height it can deliver. The capability of the pump at a certain RPM can be read from its Q-H curve, a common misconception is that the head equals the fluids energy per unit weight, while, in fact, the term with pressure does not represent any type of energy. Head is useful in specifying centrifugal pumps because their pumping characteristics tend to be independent of the fluids density, there are four types of head used to calculate the total head in and out of a pump, Velocity head is due to the bulk motion of a fluid. Its pressure head correspondent is the dynamic pressure, elevation head is due to the fluids weight, the gravitational force acting on a column of fluid. Pressure head is due to the pressure, the internal molecular motion of a fluid that exerts a force on its container. Resistance head is due to the forces acting against a fluids motion by the container. In a flowing fluid, it represents the energy of the due to its bulk motion. The total hydraulic head of a fluid is composed of pressure head, the pressure head is the equivalent gauge pressure of a column of water at the base of the piezometer, and the elevation head is the relative potential energy in terms of an elevation. The head equation, a form of the Bernoulli Principle for incompressible fluids, can be expressed as, h = ψ + z where h is the hydraulic head. This means that the hydraulic head calculation is dependent on the density of the water within the piezometer, for groundwater, it is also called the Darcy slope, since it determines the quantity of a Darcy flux or discharge. It also has applications in open-channel flow where it can be used to determine whether a reach is gaining or losing energy. This requires a hydraulic head field, which can only be obtained from a numerical model. As with any other example in physics, energy must flow from high to low and this vector can be used in conjunction with Darcys law and a tensor of hydraulic conductivity to determine the flux of water in three dimensions
Head (hydraulic)
–
Hydroelectricity generation
Head (hydraulic)
–
Available difference in hydraulic head across a
hydroelectric dam, before head losses due to turbines, wall friction and turbulence.
25.
Kinetic energy
–
In physics, the kinetic energy of an object is the energy that it possesses due to its motion. It is defined as the work needed to accelerate a body of a mass from rest to its stated velocity. Having gained this energy during its acceleration, the body maintains this kinetic energy unless its speed changes, the same amount of work is done by the body in decelerating from its current speed to a state of rest. In classical mechanics, the energy of a non-rotating object of mass m traveling at a speed v is 12 m v 2. In relativistic mechanics, this is an approximation only when v is much less than the speed of light. The standard unit of energy is the joule. The adjective kinetic has its roots in the Greek word κίνησις kinesis, the dichotomy between kinetic energy and potential energy can be traced back to Aristotles concepts of actuality and potentiality. The principle in classical mechanics that E ∝ mv2 was first developed by Gottfried Leibniz and Johann Bernoulli, Willem s Gravesande of the Netherlands provided experimental evidence of this relationship. By dropping weights from different heights into a block of clay, Émilie du Châtelet recognized the implications of the experiment and published an explanation. The terms kinetic energy and work in their present scientific meanings date back to the mid-19th century, early understandings of these ideas can be attributed to Gaspard-Gustave Coriolis, who in 1829 published the paper titled Du Calcul de lEffet des Machines outlining the mathematics of kinetic energy. William Thomson, later Lord Kelvin, is given the credit for coining the term kinetic energy c, energy occurs in many forms, including chemical energy, thermal energy, electromagnetic radiation, gravitational energy, electric energy, elastic energy, nuclear energy, and rest energy. These can be categorized in two classes, potential energy and kinetic energy. Kinetic energy is the movement energy of an object, Kinetic energy can be transferred between objects and transformed into other kinds of energy. Kinetic energy may be best understood by examples that demonstrate how it is transformed to, for example, a cyclist uses chemical energy provided by food to accelerate a bicycle to a chosen speed. On a level surface, this speed can be maintained without further work, except to overcome air resistance, the chemical energy has been converted into kinetic energy, the energy of motion, but the process is not completely efficient and produces heat within the cyclist. The kinetic energy in the moving cyclist and the bicycle can be converted to other forms, for example, the cyclist could encounter a hill just high enough to coast up, so that the bicycle comes to a complete halt at the top. The kinetic energy has now largely converted to gravitational potential energy that can be released by freewheeling down the other side of the hill. Since the bicycle lost some of its energy to friction, it never regains all of its speed without additional pedaling, the energy is not destroyed, it has only been converted to another form by friction
Kinetic energy
–
The cars of a
roller coaster reach their maximum kinetic energy when at the bottom of their path. When they start rising, the kinetic energy begins to be converted to gravitational
potential energy. The sum of kinetic and potential energy in the system remains constant, ignoring losses to
friction.
26.
Compressibility
–
In thermodynamics and fluid mechanics, compressibility is a measure of the relative volume change of a fluid or solid as a response to a pressure change. β = −1 V ∂ V ∂ p where V is volume, the specification above is incomplete, because for any object or system the magnitude of the compressibility depends strongly on whether the process is adiabatic or isothermal. Accordingly, isothermal compressibility is defined, β T = −1 V T where the subscript T indicates that the differential is to be taken at constant temperature. Isentropic compressibility is defined, β S = −1 V S where S is entropy, for a solid, the distinction between the two is usually negligible. The minus sign makes the compressibility positive in the case that an increase in pressure induces a reduction in volume, the speed of sound is defined in classical mechanics as, c 2 = S where ρ is the density of the material. It follows, by replacing partial derivatives, that the compressibility can be expressed as, β S =1 ρ c 2 The inverse of the compressibility is called the bulk modulus. That page also contains some examples for different materials, the compressibility equation relates the isothermal compressibility to the structure of the liquid. The term compressibility is also used in thermodynamics to describe the deviance in the properties of a real gas from those expected from an ideal gas. The compressibility factor is defined as Z = p V _ R T where p is the pressure of the gas, T is its temperature, and V _ is its molar volume. The deviation from ideal gas behavior tends to become particularly significant near the critical point, in these cases, a generalized compressibility chart or an alternative equation of state better suited to the problem must be utilized to produce accurate results. This pressure dependent transition occurs for atmospheric oxygen in the 2500 K to 4000 K temperature range, in transition regions, where this pressure dependent dissociation is incomplete, both beta and the differential, constant pressure heat capacity greatly increase. For moderate pressures, above 10,000 K the gas further dissociates into free electrons and ions, Z for the resulting plasma can similarly be computed for a mole of initial air, producing values between 2 and 4 for partially or singly ionized gas. Each dissociation absorbs a great deal of energy in a reversible process, ions or free radicals transported to the object surface by diffusion may release this extra energy if the surface catalyzes the slower recombination process. The isothermal compressibility is related to the isentropic compressibility by the relation, more simply stated, β T β S = γ where, γ is the heat capacity ratio. The Earth sciences use compressibility to quantify the ability of a soil or rock to reduce in volume under applied pressure and this concept is important for specific storage, when estimating groundwater reserves in confined aquifers. Geologic materials are made up of two portions, solids and voids, the void space can be full of liquid or gas. Geologic materials reduces in volume only when the spaces are reduced. This can happen over a period of time, resulting in settlement and it is an important concept in geotechnical engineering in the design of certain structural foundations
Compressibility
27.
Impulse (physics)
–
In classical mechanics, impulse is the integral of a force, F, over the time interval, t, for which it acts. Since force is a quantity, impulse is also a vector in the same direction. Impulse applied to an object produces an equivalent vector change in its linear momentum, the SI unit of impulse is the newton second, and the dimensionally equivalent unit of momentum is the kilogram meter per second. The corresponding English engineering units are the pound-second and the slug-foot per second, a resultant force causes acceleration and a change in the velocity of the body for as long as it acts. Conversely, a force applied for a long time produces the same change in momentum—the same impulse—as a larger force applied briefly. This is often called the impulse-momentum theorem, as a result, an impulse may also be regarded as the change in momentum of an object to which a resultant force is applied. Impulse has the units and dimensions as momentum. In the International System of Units, these are kg·m/s = N·s, in English engineering units, they are slug·ft/s = lbf·s. The term impulse is also used to refer to a force or impact. This type of impulse is often idealized so that the change in momentum produced by the force happens with no change in time and this sort of change is a step change, and is not physically possible. However, this is a model for computing the effects of ideal collisions. The application of Newtons second law for variable mass allows impulse, in the case of rockets, the impulse imparted can be normalized by unit of propellant expended, to create a performance parameter, specific impulse. This fact can be used to derive the Tsiolkovsky rocket equation, which relates the vehicles propulsive change in velocity to the specific impulse. Wave–particle duality defines the impulse of a wave collision, the preservation of momentum in the collision is then called phase matching. Applications include, Compton effect nonlinear optics Acousto-optic modulator Electron phonon scattering Serway, Raymond A. Jewett, John W. Physics for Scientists, Physics for Scientists and Engineers, Mechanics, Oscillations and Waves, Thermodynamics
Impulse (physics)
–
A large force applied for a very short duration, such as a golf shot, is often described as the club giving the ball an impulse.
Impulse (physics)
28.
Nozzle
–
A nozzle is a device designed to control the direction or characteristics of a fluid flow as it exits an enclosed chamber or pipe. A nozzle is often a pipe or tube of varying cross sectional area, Nozzles are frequently used to control the rate of flow, speed, direction, mass, shape, and/or the pressure of the stream that emerges from them. In a nozzle, the velocity of fluid increases at the expense of its pressure energy, a gas jet, fluid jet, or hydro jet is a nozzle intended to eject gas or fluid in a coherent stream into a surrounding medium. Gas jets are found in gas stoves, ovens, or barbecues. Gas jets were used for light before the development of electric light. Other types of jets are found in carburetors, where smooth calibrated orifices are used to regulate the flow of fuel into an engine. Another specialized jet is the laminar jet and this is a water jet that contains devices to smooth out the pressure and flow, and gives laminar flow, as its name suggests. This gives better results for fountains, the foam jet is another type of jet which uses foam instead of a gas or fluid. Nozzles used for feeding hot blast into a blast furnace or forge are called tuyeres, jet nozzles are also used in large rooms where the distribution of air via ceiling diffusers is not possible or not practical. Diffusers that uses jet nozzles are called jet diffuser where it will be arranged in the wall areas in order to distribute air. When the temperature difference between the air and the room air changes, the supply air stream is deflected upwards, to supply warm air, or downwards. Frequently, the goal of a nozzle is to increase the energy of the flowing medium at the expense of its pressure. Nozzles can be described as convergent or divergent, a de Laval nozzle has a convergent section followed by a divergent section and is often called a convergent-divergent nozzle. If the nozzle pressure ratio is high enough, then the flow will reach sonic velocity at the narrowest point, in this situation, the nozzle is said to be choked. Increasing the nozzle pressure ratio further will not increase the throat Mach number above one. Downstream the flow is free to expand to supersonic velocities, however Mach 1 can be a high speed for a hot gas because the speed of sound varies as the square root of absolute temperature. This fact is used extensively in rocketry where hypersonic flows are required, divergent nozzles slow fluids if the flow is subsonic, but they accelerate sonic or supersonic fluids. Convergent-divergent nozzles can therefore accelerate fluids that have choked in the convergent section to supersonic speeds and this CD process is more efficient than allowing a convergent nozzle to expand supersonically externally
Nozzle
–
A water nozzle
Nozzle
–
A rocket nozzle
29.
Pelton wheel
–
The Pelton wheel is an impulse type water turbine. It was invented by Lester Allan Pelton in the 1870s, the Pelton wheel extracts energy from the impulse of moving water, as opposed to waters dead weight like the traditional overshot water wheel. Many variations of impulse turbines existed prior to Peltons design, water leaving those wheels typically still had high speed, carrying away much of the dynamic energy brought to the wheels. As the water jet impinges upon the contoured bucket-blades, the direction of velocity is changed to follow the contours of the bucket. Water impulse energy exerts torque on the system, spinning the wheel. In the process, the jets momentum is transferred to the wheel. Thus, impulse energy does work on the turbine, for maximum power and efficiency, the wheel and turbine system is designed such that the water jet velocity is twice the velocity of the rotating buckets. Typically two buckets are mounted side-by-side on the wheel, which permits splitting the water jet into two equal streams and this balances the side-load forces on the wheel and helps to ensure smooth, efficient transfer of momentum of the fluid jet of water to the turbine wheel. Because water and most liquids are incompressible, almost all of the available energy is extracted in the first stage of the hydraulic turbine. Therefore, Pelton wheels have only one stage, unlike gas turbines that operate with compressible fluid. It is used for generating electricity, Pelton wheels are the preferred turbine for hydro-power, when the available water source has relatively high hydraulic head at low flow rates, where the Pelton wheel geometry is most suitable. Pelton wheels are made in all sizes, there exist multi-ton Pelton wheels mounted on vertical oil pad bearings in hydroelectric plants. The largest units can be over 400 megawatts, the smallest Pelton wheels are only a few inches across, and can be used to tap power from mountain streams having flows of a few gallons per minute. Some of these systems use household plumbing fixtures for water delivery and these small units are recommended for use with 30 metres or more of head, in order to generate significant power levels. Depending on water flow and design, Pelton wheels operate best with heads from 15–1,800 metres, the specific speed η s parameter is independent of a particular turbines size. Compared to other designs, the relatively low specific speed of the Pelton wheel. Thus it is most suitable to being fed by a source with a low ratio of flow to pressure. The specific speed is the criterion for matching a specific hydro-electric site with the optimal turbine type
Pelton wheel
–
Old Pelton wheel from Walchenseekraftwerk, Germany.
Pelton wheel
–
Assembly of a Pelton wheel at
Walchensee Hydroelectric Power Station, Germany.
Pelton wheel
–
Hydroelectricity generation
30.
Torque
–
Torque, moment, or moment of force is rotational force. Just as a force is a push or a pull. Loosely speaking, torque is a measure of the force on an object such as a bolt or a flywheel. For example, pushing or pulling the handle of a wrench connected to a nut or bolt produces a torque that loosens or tightens the nut or bolt, the symbol for torque is typically τ, the lowercase Greek letter tau. When it is called moment of force, it is denoted by M. The SI unit for torque is the newton metre, for more on the units of torque, see Units. This article follows US physics terminology in its use of the word torque, in the UK and in US mechanical engineering, this is called moment of force, usually shortened to moment. In US physics and UK physics terminology these terms are interchangeable, unlike in US mechanical engineering, Torque is defined mathematically as the rate of change of angular momentum of an object. The definition of states that one or both of the angular velocity or the moment of inertia of an object are changing. Moment is the term used for the tendency of one or more applied forces to rotate an object about an axis. For example, a force applied to a shaft causing acceleration, such as a drill bit accelerating from rest. By contrast, a force on a beam produces a moment, but since the angular momentum of the beam is not changing. Similarly with any force couple on an object that has no change to its angular momentum and this article follows the US physics terminology by calling all moments by the term torque, whether or not they cause the angular momentum of an object to change. The concept of torque, also called moment or couple, originated with the studies of Archimedes on levers, the term torque was apparently introduced into English scientific literature by James Thomson, the brother of Lord Kelvin, in 1884. A force applied at an angle to a lever multiplied by its distance from the levers fulcrum is its torque. A force of three newtons applied two metres from the fulcrum, for example, exerts the same torque as a force of one newton applied six metres from the fulcrum. More generally, the torque on a particle can be defined as the product, τ = r × F, where r is the particles position vector relative to the fulcrum. Alternatively, τ = r F ⊥, where F⊥ is the amount of force directed perpendicularly to the position of the particle, any force directed parallel to the particles position vector does not produce a torque
Torque
31.
Draft tube
–
In power turbines like reaction turbines, Kaplan turbines, or Francis turbines, a diffuser tube is installed at the exit of the runner, known as draft tube. In an impulse turbine the available head is high and there is no significant effect on the efficiency if the turbine is placed a couple of meters above the tail race. But in the case of reaction turbines, if the net head is low and if the turbine is installed above the tail race, there can be appreciable loss in available pressure head. If the pressure at the exit of the turbine is lower than the pressure of fluid in the tail race, a back flow of liquid into the turbine can result in significant damage. By placing a diffusing pipe at the exit of the runner, the head is increased by decreasing the exit velocity. A draft tube at the end of the turbine increases the pressure of the fluid at the expense of its velocity. This means that the turbine can reduce pressure to an extent without fear of back flow from tail race. The Draft tube gives an advantage of placing the turbine above the race so that any required inspections can be made easily. Moreover, it converts the wasteful kinetic energy at the exit of the runner into the useful pressure energy. Cavitation occurs when the absolute pressure falls below the saturated vapor pressure of the water for the water temperature. The height of draft tube is an important parameter for avoiding cavitation, conical diffuser or straight divergent tube-This type of draft tube consists of a conical diffuser with half angle generally less than equal to 10° to prevent flow separation. It is usually employed for low speed, vertical shaft francis turbine. Efficiency of this type of tube is 90%2. Simple elbow type draft Tube-It consists of an extended elbow type tube, generally, used when turbine has to be placed close to the tail-race. It helps to cut down the cost of excavation and the diameter should be as large as possible to recover kinetic energy at the outlet of runner. Efficiency of this kind of tube is less almost 60%3
Draft tube
–
Draft tube installed above tail race
Draft tube
–
Conical draft tube
Draft tube
–
simple elbow draft tube
Draft tube
–
Elbow type with rectangular cross section
32.
Francis turbine
–
The Francis turbine is a type of water turbine that was developed by James B. Francis in Lowell, Massachusetts. It is a reaction turbine that combines radial and axial flow concepts. Francis turbines are the most common water turbine in use today and they operate in a water head from 40 to 600 m and are primarily used for electrical power production. The electric generators that most often use this type of turbine have an output that generally ranges just a few kilowatts up to 800 MW. Penstock diameters are between 3 and 33 ft, the speed range of the turbine is from 75 to 1000 rpm. A wicket gate around the outside of the turbines rotating runner controls the rate of flow through the turbine for different power production rates. Francis turbines are almost always mounted with the vertical to isolate water from the generator. This also facilitates installation and maintenance, water wheels of different types have been used historically for more than 1,000 years to power mills of all types, but they were relatively inefficient. Nineteenth-century efficiency improvements of water turbines allowed them to nearly all water wheel applications. After electric generators were developed in the late 1800s turbines were a source of generator power where potential hydro-power sources existed. In 1826 Benoit Fourneyron developed a high efficiency outward-flow water turbine, water was directed tangentially through the turbine runner, causing it to spin. Jean-Victor Poncelet designed a turbine in about 1820 that used the same principles. Howd obtained a US patent in 1838 for a similar design and he applied scientific principles and testing methods to produce a very efficient turbine design. More importantly, his mathematical and graphical calculation methods improved turbine design and his analytical methods allowed confident design of high efficiency turbines to precisely match a sites water flow and pressure. A Francis turbine consists of the main parts, Spiral casing. Throughout its length, it has openings at regular intervals to allow the working fluid to impinge on the blades of the runner. These openings convert the energy of the fluid into momentum energy just before the fluid impinges on the blades. Guide or stay vanes, The primary function of the guide or stay vanes is to convert the energy of the fluid into the momentum energy
Francis turbine
–
Side-view cutaway of a vertical Francis turbine. Here water enters horizontally in a spiral shaped pipe (spiral case) wrapped around the outside of the turbine's rotating runner and exits vertically down through the center of the turbine.
Francis turbine
–
Pawtucket Gatehouse in Lowell, Massachusetts; site of the first Francis turbine
Francis turbine
–
Francis Runner,
Grand Coulee Dam
Francis turbine
–
Three Gorges Dam Francis turbine runner
33.
Wind turbine
–
A wind turbine is a device that converts the winds kinetic energy into electrical power. Wind turbines are manufactured in a range of vertical and horizontal axis types. The smallest turbines are used for such as battery charging for auxiliary power for boats or caravans or to power traffic warning signs. Slightly larger turbines can be used for making contributions to a power supply while selling unused power back to the utility supplier via the electrical grid. Wind turbines were used in Persia about 500–900 A. D, the windwheel of Hero of Alexandria marks one of the first known instances of wind powering a machine in history. However, the first known practical wind turbines were built in Sistan and these Panemone were vertical axle wind turbines, which had long vertical drive shafts with rectangular blades. Made of six to twelve sails covered in reed matting or cloth material, these turbines were used to grind grain or draw up water. Wind turbines first appeared in Europe during the Middle Ages, the first historical records of their use in England date to the 11th or 12th centuries and there are reports of German crusaders taking their windmill-making skills to Syria around 1190. By the 14th century, Dutch wind turbines were in use to areas of the Rhine delta. Advanced wind mills were described by Croatian inventor Fausto Veranzio, in his book Machinae Novae he described vertical axis wind turbines with curved or V-shaped blades. The first electricity-generating wind turbine was a battery charging machine installed in July 1887 by Scottish academic James Blyth to light his home in Marykirk. Some months later American inventor Charles F, although Blyths turbine was considered uneconomical in the United Kingdom electricity generation by wind turbines was more cost effective in countries with widely scattered populations. In Denmark by 1900, there were about 2500 windmills for mechanical loads such as pumps and mills, the largest machines were on 24-meter towers with four-bladed 23-meter diameter rotors. By 1908 there were 72 wind-driven electric generators operating in the United States from 5 kW to 25 kW, around the time of World War I, American windmill makers were producing 100,000 farm windmills each year, mostly for water-pumping. By the 1930s, wind generators for electricity were common on farms, in this period, high-tensile steel was cheap, and the generators were placed atop prefabricated open steel lattice towers. A forerunner of modern wind generators was in service at Yalta. This was a 100 kW generator on a 30-meter tower, connected to the local 6.3 kV distribution system and it was reported to have an annual capacity factor of 32 percent, not much different from current wind machines. In the autumn of 1941, the first megawatt-class wind turbine was synchronized to a utility grid in Vermont, the Smith-Putnam wind turbine only ran for 1,100 hours before suffering a critical failure
Wind turbine
–
Offshore wind farm, using 5 MW turbines
REpower 5M in the
North Sea off the coast of
Belgium.
Wind turbine
–
James Blyth's electricity-generating wind turbine, photographed in 1891
Wind turbine
–
The first automatically operated wind turbine, built in Cleveland in 1887 by Charles F. Brush. It was 60 feet (18 m) tall, weighed 4 tons (3.6 metric tonnes) and powered a 12 kW generator.
Wind turbine
–
Nordex N117/2400 in
Germany, a modern low-wind turbine.
34.
Airfoil
–
An airfoil or aerofoil is the shape of a wing, blade, or sail. An airfoil-shaped body moved through a fluid produces an aerodynamic force, the component of this force perpendicular to the direction of motion is called lift. The component parallel to the direction of motion is called drag, subsonic flight airfoils have a characteristic shape with a rounded leading edge, followed by a sharp trailing edge, often with a symmetric curvature of upper and lower surfaces. Foils of similar function designed with water as the fluid are called hydrofoils. The lift on an airfoil is primarily the result of its angle of attack, when oriented at a suitable angle, the airfoil deflects the oncoming air, resulting in a force on the airfoil in the direction opposite to the deflection. This force is known as force and can be resolved into two components, lift and drag. Most foil shapes require an angle of attack to generate lift. This turning of the air in the vicinity of the airfoil creates curved streamlines, resulting in pressure on one side. The lift force can be related directly to the average top/bottom velocity difference without computing the pressure by using the concept of circulation, a fixed-wing aircrafts wings, horizontal, and vertical stabilizers are built with airfoil-shaped cross sections, as are helicopter rotor blades. Airfoils are also found in propellers, fans, compressors and turbines, sails are also airfoils, and the underwater surfaces of sailboats, such as the centerboard and keel, are similar in cross-section and operate on the same principles as airfoils. Swimming and flying creatures and even many plants and sessile organisms employ airfoils/hydrofoils, common examples being bird wings, the bodies of fish, an airfoil-shaped wing can create downforce on an automobile or other motor vehicle, improving traction. Any object with an angle of attack in a fluid, such as a flat plate. Airfoils are more efficient lifting shapes, able to more lift. A lift and drag curve obtained in wind tunnel testing is shown on the right, the curve represents an airfoil with a positive camber so some lift is produced at zero angle of attack. With increased angle of attack, lift increases in a linear relation. At about 18 degrees this airfoil stalls, and lift falls off quickly beyond that, the drop in lift can be explained by the action of the upper-surface boundary layer, which separates and greatly thickens over the upper surface at and past the stall angle. The thicker boundary layer also causes an increase in pressure drag, so that the overall drag increases sharply near. Airfoil design is a facet of aerodynamics
Airfoil
–
Lift and Drag curves for a typical airfoil
Airfoil
–
Examples of airfoils in nature and within various vehicles. Though not strictly an airfoil, the dolphin flipper obeys the same principles in a different fluid medium.
Airfoil
–
An airfoil section is displayed at the tip of this
Denney Kitfox aircraft, built in 1991.
Airfoil
–
Airfoil of Kamov Ka-26 helicopters
35.
Lift (force)
–
A fluid flowing past the surface of a body exerts a force on it. Lift is the component of force that is perpendicular to the oncoming flow direction. It contrasts with the force, which is the component of the surface force parallel to the flow direction. If the fluid is air, the force is called an aerodynamic force, in water, it is called a hydrodynamic force. Lift is also exploited in the world, and even in the plant world by the seeds of certain trees. When an aircraft is flying straight and level most of the lift opposes gravity, however, when an aircraft is climbing, descending, or banking in a turn the lift is tilted with respect to the vertical. Lift may also be entirely downwards in some aerobatic manoeuvres, or on the wing on a racing car, in this last case, the term downforce is often used. Lift may also be horizontal, for instance on a sail on a sailboat. Aerodynamic lift is distinguished from other kinds of lift in fluids, Aerodynamic lift requires relative motion of the fluid which distinguishes it from aerostatic lift or buoyancy lift as used by balloons, blimps, and dirigibles. An airfoil is a shape that is capable of generating significantly more lift than drag. A flat plate can generate lift, but not as much as a streamlined airfoil, there are several ways to explain how an airfoil generates lift. Some are more complicated or more rigorous than others, some have been shown to be incorrect. For example, there are based directly on Newton’s laws of motion. Either can be used to explain lift, an airfoil generates lift by exerting a downward force on the air as it flows past. According to Newtons third law, the air must exert an equal and opposite force on the airfoil, the air flow changes direction as it passes the airfoil and follows a path that is curved downward. According to Newtons second law, this change in flow direction requires a force applied to the air by the airfoil. Then, according to Newtons third law, the air must exert a force on the airfoil. The overall result is that a force, the lift, is generated opposite to the directional change
Lift (force)
–
Boeing 747-8F landing
Lift (force)
–
Lift is defined as the component of the total aerodynamic force perpendicular to the flow direction, and drag is the component parallel to the flow direction
Lift (force)
–
A cross-section of a wing defines an airfoil shape
Lift (force)
–
Angle of attack of an airfoil
36.
Flow conditioning
–
However, they produce only marginal improvements in measurement accuracy and may still require significant length of straight pipe, which a cramped installation site may not permit. Natural gas that carries a lot of liquids with it is known as wet gas whereas natural gas that is produced without liquid is known dry gas, Dry gas is also treated as to remove all liquids. The effect of flow conditioning for various popular meters which is used in gas measurement is explained below, the most important as well as most difficult to measure aspects of flow measurement are flow conditions within a pipe upstream of a meter. It will change the value from the original calibration state referred to as reference conditions that are free of installation effects, how these installation effects impact the meter is very important since devices which create upstream installation effects are common components of any standard metering design. The meter calibration factors are only of geometric and dynamic similarity exists between the metering and calibration conditions. In fluid mechanics, this is referred to as the Law of Similarity. The principle of Law of Similarity is used extensively for theoretical and experimental fluid machines, with respect to calibration of flowmeters, the Law of Similarity is the foundation for flow measurement standards. This approach assumes that the technology does not exhibit any significant sensitivity to operating or mechanical variations between calibrations. The meter factor determined at the time of calibration is valid if both dynamic and geometric similarity exists between the installation and the laboratory installation of the artifact. A proper manufacturer’s experimental pattern locates sensitive regions to explore, measure, the manufacturer’s recommended correlation method is a rational basis for performance prediction provided the physics do not change. For instance, the physics are different between subsonic and sonic flow and this approach assumes that the selected technology does not exhibit any significant sensitivity to operating or mechanical variations between calibrations. The meter factor determined at the time of calibration is valid if both dynamic and geometric similarity exists in the “field meter installation” over the custody transfer period. The most commonly used description of conditions within the pipe is the flow velocity profile. Fig. shows the flow velocity profile for natural gas measurement. The shape of the velocity profile is given by the following equation. The eq. can be used to determine the flow profiles shape within the pipe by fitting a curve to experimentally measured velocity data, in 1993, the transverse flow velocities were being measured within the high pressure natural gas environment using hot wire technology to accomplish the data fit. A fully developed flow profile was used as the state for meter calibration and determination of Coefficient of Discharge. For Reynolds Number 105 to 106 n is approximately 7.5, since n is a function of Reynolds Number and friction factor, more accurate values of n can be estimated by using the eq
Flow conditioning
–
Figure (6) showing Ultrasonic meter sound path - uniform velocity profile
Flow conditioning
–
Figure (a) showing The Flow conditioner
37.
Classical mechanics
–
In physics, classical mechanics is one of the two major sub-fields of mechanics, along with quantum mechanics. Classical mechanics is concerned with the set of physical laws describing the motion of bodies under the influence of a system of forces. The study of the motion of bodies is an ancient one, making classical mechanics one of the oldest and largest subjects in science, engineering and technology. Classical mechanics describes the motion of objects, from projectiles to parts of machinery, as well as astronomical objects, such as spacecraft, planets, stars. Within classical mechanics are fields of study that describe the behavior of solids, liquids and gases, Classical mechanics also provides extremely accurate results as long as the domain of study is restricted to large objects and the speeds involved do not approach the speed of light. When both quantum and classical mechanics cannot apply, such as at the level with high speeds. Since these aspects of physics were developed long before the emergence of quantum physics and relativity, however, a number of modern sources do include relativistic mechanics, which in their view represents classical mechanics in its most developed and accurate form. Later, more abstract and general methods were developed, leading to reformulations of classical mechanics known as Lagrangian mechanics and these advances were largely made in the 18th and 19th centuries, and they extend substantially beyond Newtons work, particularly through their use of analytical mechanics. The following introduces the concepts of classical mechanics. For simplicity, it often models real-world objects as point particles, the motion of a point particle is characterized by a small number of parameters, its position, mass, and the forces applied to it. Each of these parameters is discussed in turn, in reality, the kind of objects that classical mechanics can describe always have a non-zero size. Objects with non-zero size have more complicated behavior than hypothetical point particles, because of the degrees of freedom. However, the results for point particles can be used to such objects by treating them as composite objects. The center of mass of a composite object behaves like a point particle, Classical mechanics uses common-sense notions of how matter and forces exist and interact. It assumes that matter and energy have definite, knowable attributes such as where an object is in space, non-relativistic mechanics also assumes that forces act instantaneously. The position of a point particle is defined with respect to a fixed reference point in space called the origin O, in space. A simple coordinate system might describe the position of a point P by means of a designated as r. In general, the point particle need not be stationary relative to O, such that r is a function of t, the time
Classical mechanics
–
Sir
Isaac Newton (1643–1727), an influential figure in the history of physics and whose
three laws of motion form the basis of classical mechanics
Classical mechanics
–
Diagram of orbital motion of a satellite around the earth, showing perpendicular velocity and acceleration (force) vectors.
Classical mechanics
–
Hamilton 's greatest contribution is perhaps the reformulation of
Newtonian mechanics, now called
Hamiltonian mechanics.
38.
Velocity triangle
–
In turbomachinery, a velocity triangle or a velocity diagram is a triangle representing the various components of velocities of the working fluid in a turbomachine. Velocity triangles may be drawn for both the inlet and outlet sections of any turbomachine, a general velocity triangle consists of the following vectors, V, Absolute velocity of the fluid. Vr, Relative velocity of the fluid after contact with rotor, vw, Tangential component of V, called Whirl velocity. The following angles are encountered during the analysis, α, Angle made by V with the plane of the machine, β, Angle of the rotor blade
Velocity triangle
–
An example of a velocity triangle drawn for the inlet of a turbomachine. The "1" subscript denotes the inlet.
39.
Computational fluid dynamics
–
Computational fluid dynamics is a branch of fluid mechanics that uses numerical analysis and data structures to solve and analyze problems that involve fluid flows. Computers are used to perform the required to simulate the interaction of liquids. With high-speed supercomputers, better solutions can be achieved, ongoing research yields software that improves the accuracy and speed of complex simulation scenarios such as transonic or turbulent flows. Initial experimental validation of such software is performed using a tunnel with the final validation coming in full-scale testing. The fundamental basis of almost all CFD problems is the Navier–Stokes equations and these equations can be simplified by removing terms describing viscous actions to yield the Euler equations. Further simplification, by removing terms describing vorticity yields the full potential equations, finally, for small perturbations in subsonic and supersonic flows these equations can be linearized to yield the linearized potential equations. Historically, methods were first developed to solve the potential equations. Two-dimensional methods, using conformal transformations of the flow about a cylinder to the flow about an airfoil were developed in the 1930s. One of the earliest type of calculations resembling modern CFD are those by Lewis Fry Richardson, in the sense that these calculations used finite differences and divided the physical space in cells. Although they failed dramatically, these calculations, together with Richardsons book Weather prediction by numerical process, set the basis for modern CFD, in fact, early CFD calculations during the 1940s using ENIAC used methods close to those in Richardsons 1922 book. The computer power available paced development of three-dimensional methods, probably the first work using computers to model fluid flow, as governed by the Navier-Stokes equations, was performed at Los Alamos National Lab, in the T3 group. This group was led by Francis H. Harlow, who is considered as one of the pioneers of CFD. Fromms vorticity-stream-function method for 2D, transient, incompressible flow was the first treatment of strongly contorting incompressible flows in the world, the first paper with three-dimensional model was published by John Hess and A. M. O. Smith of Douglas Aircraft in 1967 and this method discretized the surface of the geometry with panels, giving rise to this class of programs being called Panel Methods. Their method itself was simplified, in that it did not include lifting flows and hence was mainly applied to ship hulls, the first lifting Panel Code was described in a paper written by Paul Rubbert and Gary Saaris of Boeing Aircraft in 1968. In time, more advanced three-dimensional Panel Codes were developed at Boeing, Lockheed, Douglas, McDonnell Aircraft, NASA, some were higher order codes, using higher order distributions of surface singularities, while others used single singularities on each surface panel. The advantage of the lower order codes was that they ran much faster on the computers of the time, today, VSAERO has grown to be a multi-order code and is the most widely used program of this class. It has been used in the development of submarines, surface ships, automobiles, helicopters, aircraft
Computational fluid dynamics
–
Computational physics
Computational fluid dynamics
–
A computer simulation of high velocity air flow around the
Space Shuttle during re-entry.
Computational fluid dynamics
–
A simulation of the
Hyper-X scramjet vehicle in operation at
Mach -7
Computational fluid dynamics
–
Volume rendering of a non-premixed swirl flame as simulated by LES.
40.
Coal
–
Coal is a combustible black or brownish-black sedimentary rock usually occurring in rock strata in layers or veins called coal beds or coal seams. The harder forms, such as coal, can be regarded as metamorphic rock because of later exposure to elevated temperature and pressure. Coal is composed primarily of carbon, along with quantities of other elements, chiefly hydrogen, sulfur, oxygen. A fossil fuel, coal forms when plant matter is converted into peat, which in turn is converted into lignite, then sub-bituminous coal, after that bituminous coal. This involves biological and geological processes that take place over time, throughout history, coal has been used as an energy resource, primarily burned for the production of electricity and heat, and is also used for industrial purposes, such as refining metals. Coal is the largest source of energy for the generation of electricity worldwide, the extraction of coal, its use in energy production and its byproducts are all associated with environmental and health effects including climate change. Coal is extracted from the ground by coal mining, since 1983, the worlds top coal producer has been China. In 2015 China produced 3,747 million tonnes of coal –47. 7% of 7,861 million tonnes world coal production, in 2015 other large producers were United States, India, European Union and Australia. The word originally took the col in Old English, from Proto-Germanic *kula. In Old Turkic languages, kül is ash, cinders, öčür is quench, the compound charcoal in Turkic is öčür kül, literally quenched ashes, cinders, coals with elided anlaut ö- and inflection affixes -ülmüş. At various times in the geologic past, the Earth had dense forests in low-lying wetland areas, due to natural processes such as flooding, these forests were buried underneath soil. As more and more soil deposited over them, they were compressed, the temperature also rose as they sank deeper and deeper. As the process continued the plant matter was protected from biodegradation and oxidation and this trapped the carbon in immense peat bogs that were eventually covered and deeply buried by sediments. Under high pressure and high temperature, dead vegetation was slowly converted to coal, as coal contains mainly carbon, the conversion of dead vegetation into coal is called carbonization. The wide, shallow seas of the Carboniferous Period provided ideal conditions for coal formation, the exception is the coal gap in the Permian–Triassic extinction event, where coal is rare. Coal is known from Precambrian strata, which predate land plants — this coal is presumed to have originated from residues of algae, in its dehydrated form, peat is a highly effective absorbent for fuel and oil spills on land and water. It is also used as a conditioner for soil to make it able to retain. Lignite, or brown coal, is the lowest rank of coal, jet, a compact form of lignite, is sometimes polished and has been used as an ornamental stone since the Upper Palaeolithic
Coal
–
Anthracite coal
Coal
–
Bituminous coal
Coal
–
Coastal exposure of the Point Aconi Seam (Nova Scotia)
Coal
–
Coal miner in Britain, 1942
41.
Fuel oil
–
Fuel oil, is a fraction obtained from petroleum distillation, either as a distillate or a residue. In this sense, diesel is a type of fuel oil, Fuel oil is made of long hydrocarbon chains, particularly alkanes, cycloalkanes and aromatics. The term fuel oil is used in a stricter sense to refer only to the heaviest commercial fuel that can be obtained from crude oil, i. e. heavier than gasoline. In some countries, the fuel oil usually refers specifically to diesel fuel while in Australia. Although the following trends generally hold true, different organizations may have different numerical specifications for the six fuel grades, the boiling point and carbon chain length of the fuel increases with fuel oil number. Viscosity also increases with number, and the heaviest oil must be heated for it to flow, price usually decreases as the fuel number increases. Number 1 fuel oil is a distillate oil intended for vaporizing pot-type burners. It is the kerosene refinery cut that boils off immediately after the heavy naphtha cut used for gasoline, former names include, coal oil, stove oil and range oil. Number 2 fuel oil is a home heating oil. This fuel is known as Bunker A. Trucks and some cars use similar diesel fuel with a cetane number limit describing the quality of the fuel. Both are typically obtained from the gas oil cut. Gas oil refers to the use of this fraction in the late 19th. Number 3 fuel oil was an oil for burners requiring low-viscosity fuel. ASTM merged this grade into the number 2 specification, and the term has been used since the mid-20th century. Number 4 fuel oil is a heating oil for burner installations not equipped with preheaters. It may be obtained from the gas oil cut. Number 5 fuel oil is an industrial heating oil requiring preheating to 77–104 °C for proper atomization at the burners
Fuel oil
–
An
oil tanker taking on bunker fuel.
Fuel oil
–
A sample of residual fuel oil
Fuel oil
–
A fuel station in
Zigui County on the
Yangtze River
Fuel oil
–
Fuel oil truck making a delivery in North Carolina, 1945.
42.
Nuclear fuel
–
Nuclear fuel is a substance that is used in nuclear power stations to produce heat to power turbines. Heat is created when nuclear fuel undergoes nuclear fission, most nuclear fuels contain heavy fissile elements that are capable of nuclear fission, such as uranium-235 or plutonium-239. When the unstable nuclei of atoms are hit by a slow-moving neutron, they split. These neutrons then go on to split more nuclei and this creates a self-sustaining chain reaction that is controlled in a nuclear reactor, or uncontrolled in a nuclear weapon. The processes involved in mining, refining, purifying, using, Nuclear fuel has the highest energy density of all practical fuel sources. Uranium dioxide is a black semiconducting solid and it can be made by reacting uranyl nitrate with a base to form a solid. It is heated to form U3O8 that can then be converted by heating in an argon / hydrogen mixture to form UO2, the UO2 is then mixed with an organic binder and pressed into pellets, these pellets are then fired at a much higher temperature to sinter the solid. The aim is to form a solid which has few pores. The thermal conductivity of uranium dioxide is low compared with that of zirconium metal. It is important to note that the corrosion of uranium dioxide in an environment is controlled by similar electrochemical processes to the galvanic corrosion of a metal surface. Mixed oxide, or MOX fuel, is a blend of plutonium, MOX fuel is an alternative to low enriched uranium fuel used in the light water reactors which predominate nuclear power generation. Some concern has been expressed that used MOX cores will introduce new disposal challenges, reprocessing of commercial nuclear fuel to make MOX was done in the Sellafield MOX Plant. As of 2015, MOX fuel is made in France, and to an extent in Russia, India. China plans to develop fast breeder reactors and reprocessing, reprocessing of spent commercial-reactor nuclear fuel has not been permitted in the United States due to nonproliferation considerations. It behaves like U-235 and its fission releases a similar amount of energy, the higher the burn-up, the more plutonium in the spent fuel, but the lower the fraction of fissile plutonium. Typically about one percent of the used fuel discharged from a reactor is plutonium, worldwide, some 70 tonnes of plutonium contained in used fuel is removed when refueling reactors each year. Metal fuels have the advantage of a higher heat conductivity than oxide fuels. Metal fuels have a history of use, stretching from the Clementine reactor in 1946 to many test
Nuclear fuel
–
Close-up of a replica of the core of the
research reactor at the
Institut Laue-Langevin
Nuclear fuel
–
Nuclear Fuel Process
Nuclear fuel
–
Nuclear Regulatory Commission (NRC) photo of unirradiated (fresh) fuel pellets.
Nuclear fuel
–
NRC photo of fresh fuel pellets ready for assembly.
43.
Propeller
–
A propeller is a type of fan that transmits power by converting rotational motion into thrust. A pressure difference is produced between the forward and rear surfaces of the blade, and a fluid is accelerated behind the blade. Their disadvantages are higher mechanical complexity and higher cost, the principle employed in using a screw propeller is used in sculling. It is part of the skill of propelling a Venetian gondola but was used in a less refined way in parts of Europe. For example, propelling a canoe with a paddle using a pitch stroke or side slipping a canoe with a scull involves a similar technique. In China, sculling, called lu, was used by the 3rd century AD. In sculling, a blade is moved through an arc. The innovation introduced with the propeller was the extension of that arc through more than 360° by attaching the blade to a rotating shaft. Propellers can have a blade, but in practice there are nearly always more than one so as to balance the forces involved. The origin of the screw propeller starts with Archimedes, who used a screw to lift water for irrigation and bailing boats and it was probably an application of spiral movement in space to a hollow segmented water-wheel used for irrigation by Egyptians for centuries. Leonardo da Vinci adopted the principle to drive his theoretical helicopter, in 1784, J. P. Paucton proposed a gyrocopter-like aircraft using similar screws for both lift and propulsion. At about the time, James Watt proposed using screws to propel boats. This was not his own invention, though, Toogood and Hays had patented it a century earlier, by 1827, Czech-Austrian inventor Josef Ressel had invented a screw propeller which had multiple blades fastened around a conical base. He had tested his propeller in February 1826 on a ship that was manually driven. He was successful in using his bronze screw propeller on an adapted steamboat and his ship Civetta with 48 gross register tons, reached a speed of about six knots. This was the first ship successfully driven by an Archimedes screw-type propeller, after a new steam engine had an accident his experiments were banned by the Austro-Hungarian police as dangerous. Josef Ressel was at the time a forestry inspector for the Austrian Empire, but before this he received an Austro-Hungarian patent for his propeller. This new method of propulsion was an improvement over the paddlewheel as it was not so affected by either ship motions or changes in draft as the burned coal
Propeller
–
Propeller on a modern mid-sized merchant vessel. The propeller rotates clockwise to propel the ship forward when viewed from astern (right of picture), the person in the picture has his hand on the propeller's trailing edge
Propeller
–
Archimedes' screw.
Propeller
–
Propellers of the
RMS Olympic, a sister ship to the
RMS Titanic.
Propeller
–
Smith's original 1836 patent for a screw propeller of two full turns. He would later revise the patent, reducing the length to one turn.
44.
Turbinia
–
Turbinia was the first steam turbine-powered steamship. The vessel can still be seen at the Discovery Museum in Newcastle upon Tyne, North East England, while her original powerplant can be found at the London Science Museum. Charles Algernon Parsons invented the steam turbine in 1884, and, having foreseen its potential to power ships. To develop this he had the experimental vessel Turbinia built in a design of steel by the firm of Brown and Hood. The Admiralty was kept informed of developments, and Turbinia was launched on 2 August 1894, despite the success of the turbine engine, initial trials with one propeller were disappointing. In trials this achieved a top speed of over 34 knots, the turbines were directly driven, as geared turbines were not introduced until 1910. Even after the introduction of geared turbines, efficiency of even the largest axial steam turbines was still below 12 percent, Turbinia was even less efficient, with its direct drive turbine moving with a tip speed of just 30 meters per second. Despite this, it was an improvement over predecessors. Photographer and cinematographer Alfred J. West took several photographs of Turbinia traveling at speed at the Review. Both vessels were later lost but although the loss of these trials ships slowed the introduction of turbines, in 1900 Turbinia steamed to Paris and was shown to French officials and then displayed at the Paris Exhibition. The first turbine-powered merchant vessel, the Clyde steamer TS King Edward, the Admiralty confirmed in 1905 that all future Royal Navy vessels were to be turbine-powered, and in 1906 the first turbine-powered battleship, the revolutionary HMS Dreadnought, was launched. On 11 January 1907, Turbinia was struck and nearly cut in two by Crosby – a ship being launched across-river from the bank of the Tyne. She was repaired and steamed alongside RMS Mauretania after the launch of the ocean liner. However, mechanical problems prevented Turbinia from accompanying Mauretania down the River Tyne to the sea, the fore section was presented in 1944 to Newcastle Corporation and placed on display in the citys Exhibition Park. In 1983 a complete reconstruction was undertaken, on 30 October 1994,100 years after her launch, Turbinia was moved to Newcastles Museum of Science and Engineering and put on display to the public in March 1996. Listed as part of the National Historic Fleet, in 2000, the gallery around Turbinia was the first area to be refurbished, with the main part of the work involving raising the roof by one storey to create viewing galleries on three levels. A detailed Museum originated blog entry by Ian Whitehead, the Tyne & Wear Archives & Museums curator charged with Turbinas care in 2013
Turbinia
–
Turbinia at speed in 1897
Turbinia
–
The damaged Turbinia lying in the dry dock
Turbinia
–
Turbinia alongside RMS Mauretania
Turbinia
–
Turbinia on display at Newcastle Discovery Museum, 2013
45.
Steam launch
–
A steamboat is a boat that is propelled primarily by steam power, typically driving propellers or paddlewheels. Steamboats sometimes use the prefix designation SS, S. S. or S/S or PS, the term steamboat is used to refer to smaller, insular, steam-powered boats working on lakes and rivers, particularly riverboats. As using steam became more reliable, steam power became applied to larger, Early attempts at powering a boat by steam were made by the French inventor Denis Papin and the English inventor Thomas Newcomen. Papin invented the steam digester and experimented with closed cylinders and pistons pushed in by atmospheric pressure, Papin proposed applying this steam pump to the operation of a paddlewheel boat and tried to market his idea in Britain. He was unable to convert the piston motion into rotary motion. Newcomens design did solve the first problem, but remained shackled to the inherent limitations of the engines of the time, a steamboat was described and patented by English physician John Allen in 1729. In 1736, Jonathan Hulls was granted a patent in England for a Newcomen engine-powered steamboat, William Henry of Lancaster, Pennsylvania, having learned of Watts engine on a visit to England, made his own engine. In 1763 he put it in a boat, the boat sank, and while Henry made an improved model, he did not appear to have much success, though he may have inspired others. At its first demonstration on 15 July 1783, Pyroscaphe travelled upstream on the river Saône for some fifteen minutes before the engine failed, presumably this was easily repaired as the boat is said to have made several such journeys. Following this, De Jouffroy attempted to get the government interested in his work, De Jouffroy did not have the funds for this, and, following the events of the French revolution, work on the project was discontinued after he left the country. Similar boats were made in 1785 by John Fitch in Philadelphia and William Symington in Dumfries and this boat could typically make 7 to 8 miles per hour and traveled more than 2,000 miles during its short length of service. The Fitch steamboat was not a success, as this travel route was adequately covered by relatively good wagon roads. The following year, a boat made 30-mile excursions, and in 1790. Miller sent King Gustav III of Sweden an actual version,100 feet long. Miller then engaged engineer William Symington to build his patent steam engine drove a stern-mounted paddle wheel in a boat in 1785. The boat was successfully tried out on Dalswinton Loch in 1788 and was followed by a steamboat the next year. The boat was built by Alexander Hart at Grangemouth to Symingtons design with a cylinder engine. Trials on the River Carron in June 1801 were successful and included towing sloops from the river Forth up the Carron and thence along the Forth, in 1801, Symington patented a horizontal steam engine directly linked to a crank
Steam launch
–
Look out (Transport Steamer) on
Tennessee River, ca. 1860 - ca. 1865
Steam launch
–
Denis Papin 's cylinder and piston apparatus, 1690
Steam launch
–
Model of steamship, built in 1784, by
Claude de Jouffroy.
Steam launch
–
Charlotte Dundas, the first practical steamboat, built by
William Symington.
46.
Electric motor
–
An electric motor is an electrical machine that converts electrical energy into mechanical energy. The reverse of this is the conversion of energy into electrical energy and is done by an electric generator. In normal motoring mode, most electric motors operate through the interaction between an electric motors magnetic field and winding currents to generate force within the motor, small motors may be found in electric watches. General-purpose motors with highly standardized dimensions and characteristics provide convenient mechanical power for industrial use, the largest of electric motors are used for ship propulsion, pipeline compression and pumped-storage applications with ratings reaching 100 megawatts. Electric motors may be classified by electric power source type, internal construction, application, type of motion output, perhaps the first electric motors were simple electrostatic devices created by the Scottish monk Andrew Gordon in the 1740s. The theoretical principle behind production of force by the interactions of an electric current. The conversion of energy into mechanical energy by electromagnetic means was demonstrated by the British scientist Michael Faraday in 1821. A free-hanging wire was dipped into a pool of mercury, on which a permanent magnet was placed, when a current was passed through the wire, the wire rotated around the magnet, showing that the current gave rise to a close circular magnetic field around the wire. This motor is often demonstrated in experiments, brine substituting for toxic mercury. Though Barlows wheel was a refinement to this Faraday demonstration. In 1827, Hungarian physicist Ányos Jedlik started experimenting with electromagnetic coils, after Jedlik solved the technical problems of the continuous rotation with the invention of the commutator, he called his early devices electromagnetic self-rotors. Although they were used only for instructional purposes, in 1828 Jedlik demonstrated the first device to contain the three components of practical DC motors, the stator, rotor and commutator. The device employed no permanent magnets, as the fields of both the stationary and revolving components were produced solely by the currents flowing through their windings. His motor set a record which was improved only four years later in September 1838 by Jacobi himself. His second motor was powerful enough to drive a boat with 14 people across a wide river and it was not until 1839/40 that other developers worldwide managed to build motors of similar and later also of higher performance. The first commutator DC electric motor capable of turning machinery was invented by the British scientist William Sturgeon in 1832, following Sturgeons work, a commutator-type direct-current electric motor made with the intention of commercial use was built by the American inventor Thomas Davenport, which he patented in 1837. The motors ran at up to 600 revolutions per minute, and powered machine tools, due to the high cost of primary battery power, the motors were commercially unsuccessful and Davenport went bankrupt. Several inventors followed Sturgeon in the development of DC motors but all encountered the same battery power cost issues, no electricity distribution had been developed at the time
Electric motor
–
Various electric motors, compared to 9 V battery.
Electric motor
–
Cutaway view through stator of induction motor.
Electric motor
–
Faraday's electromagnetic experiment, 1821
Electric motor
–
Jedlik 's "electromagnetic self-rotor", 1827 (Museum of Applied Arts, Budapest). The historic motor still works perfectly today.
47.
World War II
–
World War II, also known as the Second World War, was a global war that lasted from 1939 to 1945, although related conflicts began earlier. It involved the vast majority of the worlds countries—including all of the great powers—eventually forming two opposing alliances, the Allies and the Axis. It was the most widespread war in history, and directly involved more than 100 million people from over 30 countries. Marked by mass deaths of civilians, including the Holocaust and the bombing of industrial and population centres. These made World War II the deadliest conflict in human history, from late 1939 to early 1941, in a series of campaigns and treaties, Germany conquered or controlled much of continental Europe, and formed the Axis alliance with Italy and Japan. Under the Molotov–Ribbentrop Pact of August 1939, Germany and the Soviet Union partitioned and annexed territories of their European neighbours, Poland, Finland, Romania and the Baltic states. In December 1941, Japan attacked the United States and European colonies in the Pacific Ocean, and quickly conquered much of the Western Pacific. The Axis advance halted in 1942 when Japan lost the critical Battle of Midway, near Hawaii, in 1944, the Western Allies invaded German-occupied France, while the Soviet Union regained all of its territorial losses and invaded Germany and its allies. During 1944 and 1945 the Japanese suffered major reverses in mainland Asia in South Central China and Burma, while the Allies crippled the Japanese Navy, thus ended the war in Asia, cementing the total victory of the Allies. World War II altered the political alignment and social structure of the world, the United Nations was established to foster international co-operation and prevent future conflicts. The victorious great powers—the United States, the Soviet Union, China, the United Kingdom, the Soviet Union and the United States emerged as rival superpowers, setting the stage for the Cold War, which lasted for the next 46 years. Meanwhile, the influence of European great powers waned, while the decolonisation of Asia, most countries whose industries had been damaged moved towards economic recovery. Political integration, especially in Europe, emerged as an effort to end pre-war enmities, the start of the war in Europe is generally held to be 1 September 1939, beginning with the German invasion of Poland, Britain and France declared war on Germany two days later. The dates for the beginning of war in the Pacific include the start of the Second Sino-Japanese War on 7 July 1937, or even the Japanese invasion of Manchuria on 19 September 1931. Others follow the British historian A. J. P. Taylor, who held that the Sino-Japanese War and war in Europe and its colonies occurred simultaneously and this article uses the conventional dating. Other starting dates sometimes used for World War II include the Italian invasion of Abyssinia on 3 October 1935. The British historian Antony Beevor views the beginning of World War II as the Battles of Khalkhin Gol fought between Japan and the forces of Mongolia and the Soviet Union from May to September 1939, the exact date of the wars end is also not universally agreed upon. It was generally accepted at the time that the war ended with the armistice of 14 August 1945, rather than the formal surrender of Japan
World War II
–
Clockwise from top left: Chinese forces in the
Battle of Wanjialing, Australian
25-pounder guns during the
First Battle of El Alamein, German
Stuka dive bombers on the
Eastern Front in December 1943, a U.S. naval force in the
Lingayen Gulf,
Wilhelm Keitel signing the
German Instrument of Surrender, Soviet troops in the
Battle of Stalingrad
World War II
–
The
League of Nations assembly, held in
Geneva,
Switzerland, 1930
World War II
–
Adolf Hitler at a German
National Socialist political rally in
Weimar, October 1930
World War II
–
Italian soldiers recruited in 1935, on their way to fight the
Second Italo-Abyssinian War
48.
Transonic
–
This condition depends not only on the travel speed of the craft, but also on the temperature of the airflow in the vehicles local environment.2, when most of the airflow is supersonic. Between these speeds some of the airflow is supersonic, but a significant fraction is not, most modern jet powered aircraft are engineered to operate at transonic air speeds. Transonic airspeeds see an increase in drag from about Mach 0.8. Attempts to reduce wave drag can be seen on all high-speed aircraft, most notable is the use of swept wings, but another common form is a wasp-waist fuselage as a side effect of the Whitcomb area rule. Severe instability can occur at transonic speeds, shock waves move through the air at the speed of sound. When an object such as an aircraft also moves at the speed of sound, transonic speeds can also occur at the tips of rotor blades of helicopters and aircraft. This puts severe, unequal stresses on the blade and may lead to accidents if it occurs. It is one of the factors of the size of rotors. At transonic speeds supersonic expansion fans form intense low-pressure, low-temperature areas at various points around an aircraft, if the temperature drops below the dew point a visible cloud will form. These clouds remain with the aircraft as it travels and it is not necessary for the aircraft as a whole to reach supersonic speeds for these clouds to form. Typically, the tail of the aircraft will reach supersonic flight while the bow of the aircraft is still in subsonic flight, a bubble of supersonic expansion fans terminating by a wake shockwave surround the tail. As the aircraft continues to accelerate, the supersonic expansion fans will intensify and this is Mach one and the Prandtl–Glauert singularity. In astrophysics, wherever there is evidence of shocks, the close by must be transonic. Interestingly, all black hole accretions are transonic, many such flows also have shocks very close to the black holes. The outflows or jets from young stellar objects or disks around black holes can also be transonic since they start subsonically, supernovae explosions are accompanied by supersonic flows and shock waves. Bow shocks formed in solar winds are a result of transonic winds from a star. It has been thought that a bow shock was present around the heliosphere of our solar system. This was recently found not to be the case according to IBEX data, anti-shock body Subsonic flows Supersonic flows Hypersonic flows Supersonic expansion fans
Transonic
–
Aerodynamic condensation evidences of
supersonic expansion fans around a transonic
F/A-18
Transonic
–
Shock waves may appear as weak optical disturbances above airliners with
supercritical wings
49.
Contra-rotating
–
Contra-rotating, also referred to as coaxial contra-rotating, is a technique whereby parts of a mechanism rotate in opposite directions about a common axis, usually to minimise the effect of torque. Examples include some aircraft propellers, resulting in the power of a single piston or turboprop engine to drive two propellers in opposite rotation. Contra-rotating propellers are also common in some marine transmission systems, in particular for large speed boats with planing hulls, two propellers are arranged one behind the other, and power is transferred from the engine via planetary gear transmission. The configuration can also be used in helicopter designs termed coaxial rotors, tandem-rotor helicopters such as the CH-47 Chinook also use a counter-rotating arrangement. The efficiency of a prop is somewhat offset by its mechanical complexity. While several nations experimented with contra-rotating propellers in aircraft, only the United Kingdom, some helicopters use contra-rotating coaxial rotors mounted one above the other. The H-43 Huskie helicopter uses non-coaxial intermeshing rotors turning in opposite directions, the F-35B variant of the new F-35 Lightning II strike fighter uses a lift fan with contra-rotating blades. Contra-rotating propellers have benefits when providing thrust for boats for the same reasons, ABB provided an azimuth thruster for ShinNihonkai Ferries in form of the CRP Azipod, claiming efficiency gains from the propeller and a simpler hull design. Volvo Penta have launched the IPS, a diesel, transmission. The propeller-induced heeling moment is compensated, more power can be transmitted for a given propeller radius. The propeller efficiency is increased by recovering energy from the flow from the leading propeller. Tangential flow does not contribute to thrust, conversion of tangential to axial flow increases both thrust and overall system efficiency, the mechanical installation of coaxial contra-rotating shafts is complicated and expensive and requires more maintenance. The hydrodynamic gains are partially reduced by losses in shafting. Contra-rotating propellers are used on torpedoes due to the natural torque compensation and are used in some motor boats. The cost of boring out the shafts and problems of mounting the inner shaft bearings are not worth pursuing in case of normal ships. Two Propellers in Tandem Turning in Opposite Ways Give Warplane New Speed
Contra-rotating
–
A Soviet
Ka-32 helicopter with
coaxial contra-rotating rotors, in 1989
Contra-rotating
–
Contra-rotating propellers on a modified
P-51 aircraft.
Contra-rotating
–
A
Mark 46 Mod 5A torpedo is inspected aboard a destroyer in April 2005
50.
Axial turbine
–
An axial turbine is a turbine in which the flow of the working fluid is parallel to the shaft, as opposed to radial turbines, where the fluid runs around a shaft, as in a watermill. An axial turbine has similar construction as a compressor, but it operates in the reverse. A set of guide vanes or nozzle vanes accelerates and adds swirl to the fluid. The angles in the system are noted by alpha and the angles in the relative system are noted by beta. Axial and tangential components of both absolute and relative velocities are shown in the figure, static and stagnation values of pressure and enthalpy in the absolute and relative systems are also shown. It is often assumed that the velocity component remains constant through the stage. The variation of pressure and velocity of the fluid through the stage is shown in Figure. The absolute velocity of the fluid increases corresponding to the drop through the nozzle blade row in which only transformation of energy occurs. The transfer of energy occurs only across the rotor blade row, therefore, the absolute fluid velocity decreases through this as shown in the figure. In the absence of any pressure drop through the rotor blades the relative velocities at their entry, to obtain this condition the rotor blade angles must be equal. Therefore, the factor is given by E = U12 c 2 When the pressure drop available is large. A single stage utilizing a pressure drop will have an impractically high peripheral speed of its rotor. This would lead to either a larger diameter or a high rotational speed. Therefore, machines with large pressure drops employ more than one stage, one of the methods to employ multi-stage expansion in impulse turbines is to generate high velocity of the fluid by causing it to expand through a large pressure drop in the nozzle blade row. This high velocity fluid then transfers its energy in a number of stages by employing many rotor blade rows separated by rows of fixed guide blades, since the turbine is of the impulse type, the pressure of the fluid remains constant after its expansion in the nozzle blade row. Such stages are referred to as velocity or Curtis stages, there are two major problems in velocity-compounded stages, The nozzles have to be of the convergent-divergent type for generating high steam velocity. This results in an expensive and difficult design of the nozzle blade rows. High velocity at the exit leads to higher cascade losses
Axial turbine
–
Contents
Axial turbine
Axial turbine
Axial turbine
