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alex April 1, 2002 07:43

Prediction
 
I understand this maybe a bit basic for you guys but I hope someone can help.

I am testing some compressor blades and comparing them with Howells empirical rule and some software based on the martensen method.

can anyone explain to me the many reasons why the results will differ and the weaknesses in these methods?

many thanks in advance

regards

dean

Nicola April 3, 2002 05:03

Re: Prediction
 
Can you explain what type of comparison have you made between experimental data and Howell and Martensen results? 1) As long as I can remember, Martensen method is an inviscid 2D flow solver, unable to estimate losses in a bladerow environment (may be you have a version with a boundary layer solver too ?). Moreover, it neglegts compressibility effects, so can be used only to study low Mach flows. You can not hope to obtain a correct model if the flow is separated or stalled, when studying low aspect ratio bladerows that can be strongly affected by secondary flows (passage vortex, horseshoe vortex, tip leakage ecc.). Its basic version is unable to model endwall variation effects too. 2) Are you sure that Howell method can be used to study your compressor blade? May be it is "out of date" for you. Anyway, Howell method does not account for 3-dimensional effects, endwall variation and it can be used only for low-Mach flows. Best regards

Nicola


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