Secondary flow in cascades - the effect of compressibility

Abstract

Kelvin's circulation theorem is applied to compressible flow through a cascade of blades and expressions are derived for the three streamwise components of vorticity at exit from the cascade. Calculations show that for a decelerating flow, such as a compressor cascade, the distributed secondary vorticity increases as the inlet Mach number increases. However, for an accelerating flow, such as a turbine cascade, there is a wide range of inlet flow angles for which compressibility has little effect on the secondary flow.