Engineering: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 [math]\displaystyle{ N/\sqrt{\theta} }[/math] can be calculated as follows:

[math]\displaystyle{ N/\sqrt{\theta} = N/\sqrt{T/288.15}. }[/math]

Corrected speed is often abbreviated to [math]\displaystyle{ N_c }[/math] or [math]\displaystyle{ N_r }[/math] (for referred speed).

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

[math]\displaystyle{ N/\sqrt{T}= (N/\sqrt{\theta}) / \sqrt{288.15} }[/math]

Nomenclature:

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

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

See also

• Compressor map
• Turbine map
• Corrected flow