Engineering:Corrected flow
Corrected Flow is the mass flow that would pass through a device (e.g. compressor, bypass duct, etc.) if the inlet pressure and temperature corresponded to ambient conditions at Sea Level, on a Standard Day (e.g. 101.325 kPa, 288.15 K).
Corrected Flow, [math]\displaystyle{ w\sqrt{\theta}/{\delta} }[/math], can be calculated as follows, assuming Imperial Units:
[math]\displaystyle{ w\sqrt{\theta}/{\delta} = w\sqrt{T/518.67}/(P/14.696) }[/math]
Corrected Flow is often given the symbol [math]\displaystyle{ wc }[/math] or [math]\displaystyle{ wr }[/math] (for referred flow).
So-called Non-Dimensional Flow, [math]\displaystyle{ w\sqrt{T}/{P} }[/math], is proportional to Corrected Flow:
[math]\displaystyle{ w\sqrt{T}/{P}= w\sqrt{\theta}/{\delta} * \sqrt{518.67}/{14.696} }[/math]
The equivalent equations for Preferred SI Units are: (101.325kPa, 288.15K)
[math]\displaystyle{ w\sqrt{\theta}/{\delta} = w\sqrt{T/288.15}/(P/101.325) }[/math]
[math]\displaystyle{ w\sqrt{T}/{P}= w\sqrt{\theta}/{\delta} * \sqrt{288.15}/{101.325} }[/math]
Nomenclature:
- [math]\displaystyle{ P }[/math] Stagnation (or Total) Pressure (in kPa)
- [math]\displaystyle{ T }[/math] Stagnation (or Total) Temperature (in K)
- [math]\displaystyle{ w }[/math] Real Mass Flow
- [math]\displaystyle{ {\delta} }[/math] Referred Pressure
- [math]\displaystyle{ {\theta} }[/math] Referred Temperature
In relative form, Corrected Flow, Referred Flow and Non-Dimensional Flow are all measures of axial Mach number.
Side note: If the mass flow can be considered an energy source such as fuel flow, the corrected flow is calculated as follows:
[math]\displaystyle{ w/(\delta * \sqrt{\theta}) }[/math]
Note:
The source of coefficients is coming out from the fact that rotating components will in fact change the fluid properties, because of vibrations (compressibility of the flow change). So if one wants to correct the fuel flow then a theta correction exponent should be found through iterations, but for corrections for flow at engine entry (W2) then this aspect on rotating components vibration is not accounted because much smaller than one inside an engine. As a consequence the inlet flow is corrected just by square root of Theta and divided by delta.
See also
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