Corrected speed

Corrected speed is the speed a component would rotate at if the inlet temperature corresponded to ambient conditions at sea level, on a standard day (i.e. 288.15 K).

Corrected speed ${\displaystyle N/{\sqrt {\theta }}}$ can be calculated as follows:

${\displaystyle N/{\sqrt {\theta }}=N/{\sqrt {T/288.15}}.}$

Corrected speed is often abbreviated to ${\displaystyle N_{c}}$ or ${\displaystyle N_{r}}$ (for referred speed).

So-called non-dimensional speed ${\displaystyle N/{\sqrt {T}}}$ is proportional to corrected speed:

${\displaystyle N/{\sqrt {T}}=(N/{\sqrt {\theta }})/{\sqrt {288.15}}}$

Nomenclature:

• ${\displaystyle T}$ – stagnation (or total) temperature (in kelvins),
• ${\displaystyle N}$ – real shaft speed,
• ${\displaystyle \theta }$ – referred temperature.

In relative form, corrected speed, referred speed and non-dimensional speed are all measures of peripheral Mach number.