Nozzle/Diffuser equation for compressible flow

DanielSauza · Dec 22, 2015

I was reading a bit about comrpessible flow and I came upon a problem, there's a diffuser which has air at Ma=0.9 at its inlet and the air comes out at 0.65, how should I go about finding the ratio of the inlet and outlet areas?

$Equation dV/V (M^2 - 1) = dA/A, relating fractional change in velocity to fractional change in area for compressible flow with Mach number M.$

I know It's related to this equation but I'm unsure about how to use it (Should I turn Ma^2 into V terms or should I just use the Ma number at the outlet?)

cjl · Dec 22, 2015

Since your desired parameters are in terms of mach number, there's no reason to complicate things by turning it into a velocity. Just use the mach number directly.

Nozzle/Diffuser equation for compressible flow

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