A gas turbine, 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 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, 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 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
A steam locomotive is a railway locomotive that produces its pulling power through a steam engine. These locomotives are fueled by burning combustible material—usually coal, the steam moves reciprocating pistons which are mechanically connected to the locomotives main wheels. Both fuel and water supplies are carried with the locomotive, either on the locomotive itself or in wagons pulled behind, the first steam locomotive, made by Richard Trevithick, first operated on 21 February 1804, three years after the road locomotive he made in 1801. The first practical steam locomotive was built in 1812-13 by John Blenkinsop, Steam locomotives were first developed in Great Britain during the early 19th century and used for railway transport until the middle of the 20th century. From the early 1900s they were superseded by electric and diesel locomotives, with full conversions to electric. The majority of locomotives were retired from regular service by the 1980s, though several continue to run on tourist.
The earliest railways employed horses to draw carts along railway tracks, in 1784, William Murdoch, a Scottish inventor, built a small-scale prototype of a steam road locomotive. An early working model of a rail locomotive was designed and constructed by steamboat pioneer John Fitch in the US during 1794. His steam locomotive used interior bladed wheels guided by rails or tracks, the model still exists at the Ohio Historical Society Museum in Columbus. The authenticity and date of this locomotive is disputed by some experts, accompanied by Andrew Vivian, it ran with mixed success. The design incorporated a number of important innovations that included using high-pressure steam which reduced the weight of the engine, Trevithick visited the Newcastle area in 1804 and had a ready audience of colliery owners and engineers. The visit was so successful that the railways in north-east England became the leading centre for experimentation. Trevithick continued his own steam propulsion experiments through another trio of locomotives, Four years later, the successful twin-cylinder locomotive Salamanca by Matthew Murray for the edge railed rack and pinion Middleton Railway debuted in 1812.
Another well known early locomotive was Puffing Billy built 1813–14 by engineer William Hedley and it was intended to work on the Wylam Colliery near Newcastle upon Tyne. This locomotive is the oldest preserved, and is on display in the Science Museum. George Stephenson built Locomotion No.1 for the Stockton and Darlington Railway, north-east England, in 1829, his son Robert built in Newcastle The Rocket which was entered in and won the Rainhill Trials. This success led to the company emerging as the pre-eminent builder of locomotives used on railways in the UK, US. The Liverpool and Manchester Railway opened a year making exclusive use of power for passenger
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 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, 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 in some atomic particle accelerators. The operating principle of electromagnetic generators was discovered in the years of 1831–1832 by Michael Faraday, the principle called Faradays law, is that an electromotive force is generated in an electrical conductor which encircles a varying magnetic flux. He 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
Oxygen is a chemical element with symbol O and atomic number 8. It is a member of the group on the periodic table and is a highly reactive nonmetal. By mass, oxygen is the third-most abundant element in the universe, after hydrogen, at standard temperature and pressure, two atoms of the element bind to form dioxygen, a colorless and odorless diatomic gas with the formula O2. This is an important part of the atmosphere and diatomic oxygen gas constitutes 20. 8% of the Earths atmosphere, additionally, as oxides the element makes up almost half of the Earths crust. Most of the mass of living organisms is oxygen as a component of water, oxygen is continuously replenished by photosynthesis, which uses the energy of sunlight to produce oxygen from water and carbon dioxide. Oxygen is too reactive to remain a free element in air without being continuously replenished by the photosynthetic action of living organisms. Another form of oxygen, strongly absorbs ultraviolet UVB radiation, but ozone is a pollutant near the surface where it is a by-product of smog.
At low earth orbit altitudes, sufficient atomic oxygen is present to cause corrosion of spacecraft, the name oxygen was coined in 1777 by Antoine Lavoisier, whose experiments with oxygen helped to discredit the then-popular phlogiston theory of combustion and corrosion. One of the first known experiments on the relationship between combustion and air was conducted by the 2nd century BCE Greek writer on mechanics, Philo of Byzantium. In his work Pneumatica, Philo observed that inverting a vessel over a burning candle, Philo incorrectly surmised that parts of the air in the vessel were converted into the classical element fire and thus were able to escape through pores in the glass. Many centuries Leonardo da Vinci built on Philos work by observing that a portion of air is consumed during combustion and respiration, Oxygen was discovered by the Polish alchemist Sendivogius, who considered it the philosophers stone. In the late 17th century, Robert Boyle proved that air is necessary for combustion, English chemist John Mayow refined this work by showing that fire requires only a part of air that he called spiritus nitroaereus.
From this he surmised that nitroaereus is consumed in both respiration and combustion, Mayow observed that antimony increased in weight when heated, and inferred that the nitroaereus must have combined with it. Accounts of these and other experiments and ideas were published in 1668 in his work Tractatus duo in the tract De respiratione. Robert Hooke, Ole Borch, Mikhail Lomonosov, and Pierre Bayen all produced oxygen in experiments in the 17th and the 18th century but none of them recognized it as a chemical element. This may have been in part due to the prevalence of the philosophy of combustion and corrosion called the phlogiston theory, which was the favored explanation of those processes. Established in 1667 by the German alchemist J. J. Becher, one part, called phlogiston, was given off when the substance containing it was burned, while the dephlogisticated part was thought to be its true form, or calx. The fact that a substance like wood gains overall weight in burning was hidden by the buoyancy of the combustion products
Alternating current, is an electric current which periodically reverses direction, whereas direct current flows only in one direction. A common source of DC power is a cell in a flashlight. The abbreviations AC and DC are often used to mean simply alternating and direct, the usual waveform of alternating current in most electric power circuits is a sine wave. In certain applications, different waveforms are used, such as triangular or square waves and radio signals carried on electrical wires are examples of alternating current. These types of alternating current carry information encoded onto the AC signal and these currents typically alternate at higher frequencies than those used in power transmission. Electrical energy is distributed as alternating current because AC voltage may be increased or decreased with a transformer, use of a higher voltage leads to significantly more efficient transmission of power. The power losses in a conductor are a product of the square of the current and this means that when transmitting a fixed power on a given wire, if the current is halved, the power loss will be four times less.
Power is often transmitted at hundreds of kilovolts, and transformed to 100–240 volts for domestic use, high voltages have disadvantages, such as the increased insulation required, and generally increased difficulty in their safe handling. In a power plant, energy is generated at a convenient voltage for the design of a generator, near the loads, the transmission voltage is stepped down to the voltages used by equipment. Consumer voltages vary somewhat depending on the country and size of load, the voltage delivered to equipment such as lighting and motor loads is standardized, with an allowable range of voltage over which equipment is expected to operate. Standard power utilization voltages and percentage tolerance vary in the different mains power systems found in the world, high-voltage direct-current electric power transmission systems have become more viable as technology has provided efficient means of changing the voltage of DC power. HVDC systems, tend to be expensive and less efficient over shorter distances than transformers.
Three-phase electrical generation is very common, the simplest way is to use three separate coils in the generator stator, physically offset by an angle of 120° to each other. Three current waveforms are produced that are equal in magnitude and 120° out of phase to each other, if coils are added opposite to these, they generate the same phases with reverse polarity and so can be simply wired together. In practice, higher pole orders are commonly used, for example, a 12-pole machine would have 36 coils. The advantage is that lower rotational speeds can be used to generate the same frequency, for example, a 2-pole machine running at 3600 rpm and a 12-pole machine running at 600 rpm produce the same frequency, the lower speed is preferable for larger machines. If the load on a system is balanced equally among the phases. Even in the worst-case unbalanced load, the current will not exceed the highest of the phase currents
A diesel generator is the combination of a diesel engine with an electric generator to generate electrical energy. This is a case of engine-generator. A diesel compression-ignition engine often is designed to run on fuel oil, proper sizing of diesel generators is critical to avoid low-load or a shortage of power. Sizing is complicated by the characteristics of modern electronics, specifically non-linear loads, the packaged combination of a diesel engine, a generator and various ancillary devices is referred to as a generating set or a genset for short. Set sizes range from 8 to 30 kW for homes, small shops and these units, referred to as power modules are gensets on large triple axle trailers weighing 85,000 pounds or more. A combination of these modules are used for power stations and these may use from one to 20 units per power section. In these larger sizes the power module are brought to site on trailers separately and are connected together with large cables, ships often employ diesel generators, sometimes not only to provide auxiliary power for lights, winches etc. but indirectly for main propulsion.
With electric propulsion the generators can be placed in a convenient position, electric drives for ships were developed prior to World War I. Such a diesel-electric arrangement is used in some very large land vehicles such as railroad locomotives. The expected duty as well as environmental conditions must be considered, most of the larger generator set manufacturers offer software that will perform the complicated sizing calculations by simply inputting site conditions and connected electrical load characteristics. One or more diesel generators operating without a connection to a grid are referred to as operating in island mode. Operating generators in parallel provides the advantage of redundancy, and can provide efficiency at partial loads. The plant brings generator sets online and takes them off line depending on the demands of the system at a given time. An islanded power plant intended for primary power source of a community will often have at least three diesel generators, any two of which are rated to carry the required load.
Groups of up to 20 are not uncommon, generators can be electrically connected together through the process of synchronization. Synchronization involves matching voltage and phase before connecting the generator to the system, failure to synchronize before connection could cause a high short circuit current or wear and tear on the generator or its switchgear. The synchronization process can be done automatically by an auto-synchronizer module, the auto-synchronizer will read the voltage and phase parameters from the generator and busbar voltages, while regulating the speed through the engine governor or ECM. Load can be shared among parallel running generators through load sharing, a diesel generator will take more load when the fuel supply to its combustion system is increased, while load is released if fuel supply is decreased
The mica group of sheet silicate minerals includes several closely related materials having nearly perfect basal cleavage. All are monoclinic, with a tendency towards pseudohexagonal crystals, and are similar in chemical composition, the nearly perfect cleavage, which is the most prominent characteristic of mica, is explained by the hexagonal sheet-like arrangement of its atoms. The word mica is derived from the Latin word mica, meaning a crumb, and probably influenced by micare, to glitter. Chemically, micas can be given the general formula X2Y4–6Z8O204 in which X is K, Na, or Ca or less commonly Ba, Rb, or Cs, Y is Al, Mg, or Fe or less commonly Mn, Cr, Ti, Li, etc. Z is chiefly Si or Al, but may include Fe3+ or Ti, micas can be classed as dioctahedral and trioctahedral. If the X ion is K or Na, the mica is a common mica, whereas if the X ion is Ca, mica is widely distributed and occurs in igneous and sedimentary regimes. Large crystals of mica used for various applications are typically mined from granitic pegmatites, until the 19th century, large crystals of mica were quite rare and expensive as a result of the limited supply in Europe.
However, their price dramatically dropped when large reserves were found and mined in Africa, the largest documented single crystal of mica was found in Lacey Mine, Canada, it measured 10 ×4.3 ×4.3 m and weighed about 330 tonnes. Similar-sized crystals were found in Karelia, Russia. The British Geological Survey reported that as of 2005, Koderma district in Jharkhand state in India had the largest deposits of mica in the world. China was the top producer of mica with almost a third of the share, closely followed by the US, South Korea. Large deposits of mica were mined in New England from the 19th century to the 1970s. Large mines existed in Connecticut, New Hampshire, and Maine and flake mica is produced all over the world. In 2010, the producers were Russia, United States, South Korea, France. The total production was 350,000 t, although no data were available for China. Most sheet mica was produced in India and Russia, flake mica comes from several sources, the metamorphic rock called schist as a byproduct of processing feldspar and kaolin resources, from placer deposits, and from pegmatites.
Sheet mica is considerably less abundant than flake and scrap mica, the most important sources of sheet mica are pegmatite deposits. Sheet mica prices vary with grade and can range from less than $1 per kilogram for low-quality mica to more than $2,000 per kilogram for the highest quality, the mica group represents 37 phyllosilicate minerals that have a layered or platy texture
A heat exchanger is a device used to transfer heat between a solid object and a fluid, or between two or more fluids. The fluids may be separated by a wall to prevent mixing or they may be in direct contact. They are widely used in heating, air conditioning, power stations, chemical plants, petrochemical plants, petroleum refineries, natural-gas processing. Another example is the heat sink, which is a heat exchanger that transfers the heat generated by an electronic or a mechanical device to a fluid medium. There are three classifications of heat exchangers according to their flow arrangement. In parallel-flow heat exchangers, the two enter the exchanger at the same end, and travel in parallel to one another to the other side. In counter-flow heat exchangers the fluids enter the exchanger from opposite ends, in a cross-flow heat exchanger, the fluids travel roughly perpendicular to one another through the exchanger. For efficiency, heat exchangers are designed to maximize the area of the wall between the two fluids, while minimizing resistance to fluid flow through the exchanger.
The exchangers performance can be affected by the addition of fins or corrugations in one or both directions, which increase surface area and may channel fluid flow or induce turbulence. The driving temperature across the heat transfer surface varies with position, in most simple systems this is the log mean temperature difference. Sometimes direct knowledge of the LMTD is not available and the NTU method is used, double pipe heat exchangers are the simplest exchangers used in industries. On one hand, these heat exchangers are cheap for both design and maintenance, making them a choice for small industries. On the other hand, their low efficiency coupled with the space occupied in large scales, has led modern industries to use more efficient heat exchangers like shell. However, since double pipe heat exchangers are simple, they are used to teach heat exchanger design basics to students as the rules for all heat exchangers are the same. Shell and tube heat exchangers consist of series of tubes, One set of these tubes contains the fluid that must be either heated or cooled.
The second fluid runs over the tubes that are being heated or cooled so that it can provide the heat or absorb the heat required. A set of tubes is called the tube bundle and can be made up of types of tubes, longitudinally finned. Shell and tube heat exchangers are used for high-pressure applications
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 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, 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 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
Auxiliary power unit
An auxiliary power unit is a device on a vehicle that provides energy for functions other than propulsion. They are commonly found on aircraft and naval ships as well as some large land vehicles. Aircraft APUs generally produce 115 V alternating current at 400 Hz, to run the electrical systems of the aircraft, APUs can provide power through single- or three-phase systems. The primary purpose of an aircraft APU is to power to start the main engines. Turbine engines must be accelerated to a rotational speed to provide sufficient air compression for self-sustaining operation. Smaller jet engines are started by an electric motor, while larger engines are usually started by an air turbine motor. Before the engines are to be turned, the APU is started, once the APU is running, it provides power to start the aircrafts main engines. To start, a jet engine requires rotation of the turbine, AC-electrical fuel pumps. As the turbine is already rotating, the front inlet fans are rotating, after the ignition, both fans and turbine speed up their rotation.
As combustion stabilizes, the engine only needs the fuel to run at idle. The started engine can now replace the APU when starting up further engines, during flight the APU and its generator are not needed. APUs are used to run accessories while the engines are shut down and this allows the cabin to be comfortable while the passengers are boarding before the aircrafts engines are started. Electrical power is used to run systems for preflight checks, some APUs are connected to a hydraulic pump, allowing crews to operate hydraulic equipment prior to engine start. This function can be used, on aircraft, as a backup in flight in case of engine or hydraulic failure. Aircraft with APUs can accept electrical and pneumatic power from ground equipment when an APU has failed or is not to be used, some airports reduce the use of APUs due to noise and pollution, and ground power is used when possible. While some APUs may not be startable in flight, ETOPS-compliant APUs must be flight-startable at altitudes up to the service ceiling.
Recent applications have specified starting up to 43,000 ft from a complete cold-soak condition such as the Hamilton Sundstrand APS5000 for the Boeing 787 Dreamliner. If the APU or its electrical generator is not available, the aircraft cannot be released for ETOPS flight and is forced to take a longer non-ETOPS route
Steam is water in the gas phase, which is formed when water boils. Steam is invisible, steam often refers to wet steam, at lower pressures, such as in the upper atmosphere or at the top of high mountains, water boils at a lower temperature than the nominal 100 °C at standard pressure. If heated further it becomes superheated steam, piston type steam engines played a central role to the Industrial Revolution and modern steam turbines are used to generate more than 80% of the worlds electricity. If liquid water comes in contact with a hot surface or depressurizes quickly below its vapor pressure. Steam explosions have been responsible for many accidents, and may have been responsible for much of the damage to the plant in the Chernobyl disaster. Steam is traditionally created by heating a boiler via burning coal and other fuels, water vapor that includes water droplets is described as wet steam. As wet steam is heated further, the droplets evaporate, and at a high temperature all of the water evaporates.
Superheated steam is steam at a higher than its boiling point for the pressure. Steam tables contain thermodynamic data for water/steam and are used by engineers and scientists in design. Additionally, thermodynamic phase diagrams for water/steam, such as a diagram or a Mollier diagram shown in this article. Steam charts are used for analysing thermodynamic cycles. In agriculture, steam is used for sterilization to avoid the use of harmful chemical agents. Steams capacity to transfer heat is used in the home, for cooking vegetables, steam cleaning of fabric and flooring. In each case, water is heated in a boiler, steam is used in ironing clothes to add enough humidity with the heat to take wrinkles out and put intentional creases into the clothing. About 90% of all electricity is generated using steam as the working fluid, in electric generation, steam is typically condensed at the end of its expansion cycle, and returned to the boiler for re-use. However, in cogeneration, steam is piped into buildings through a heating system to provide heat energy after its use in the electric generation cycle.
The worlds biggest steam generation system is the New York City steam system, in other industrial applications steam is used for energy storage, which is introduced and extracted by heat transfer, usually through pipes. Steam is a reservoir for thermal energy because of waters high heat of vaporization
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 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