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-   -   what is isentropic mach number? (http://www.cfd-online.com/Forums/numeca/51046-what-isentropic-mach-number.html)

peck110 August 15, 2007 00:56

what is isentropic mach number?
 
many thanks for the one who answer me!

Jonas Larsson August 16, 2007 04:19

Re: what is isentropic mach number?
 
I wrote a bit about this in CFD-Wiki here:

http://www.cfd-online.com/Wiki/Isentropic_Mach_number

SA March 16, 2008 02:10

Re: what is isentropic mach number?
 
how to calculate the isentropic mach number for rotating compressor blade. should that formulation be the same or we must replace the total pressure with relative total pressure

Vinayender July 8, 2008 03:15

Re: what is isentropic mach number?
 
Hi,

I guess if we take relative P0_freestream then what we get is relative ISentropic Mach no silmilarly if we take absulote P0_freestream then what we get is absolute Isentropic Mach no. Again I guess in turbomachinary people always want relative isentropic mach no so better use relative P0_Freestream.

Any how, thanks a lot Jonas for your definition of Isentropic Mach no for which i was searching for. Also thanks Peck for asking that question.

Thanks, Vinayender.

SA July 8, 2008 05:37

Re: what is isentropic mach number?
 
should we take Po at inlet or outlet? should we take the Po at inlet for both turbines and compressors.

Thanks a lot

Vinayender July 8, 2008 06:50

Re: what is isentropic mach number?
 
Hi,

We should take P0 at Inlet but not outlet because at oulet P0 might have got reduced because of losses.

It should be Inlet for both Compressor and Turbine (and your inlet can be at bottom or at top in meridonal view depending wether it is a compressor or turbine respectively).

Thanks, Vinayender.

SA July 9, 2008 13:18

Re: what is isentropic mach number?
 
Dear Vinayeder, Thanks for your nice reply: I have some confusions about this "It should be Inlet for both Compressor and Turbine (and your inlet can be at bottom or at top in meridonal view depending wether it is a compressor or turbine respectively)"

can you eloborate more. should I average pitchwise at two locations for compressor and turbine respectively?

what if I am only computing flow in rotor with uniform flow at inlet?

Thanks.



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