Compressibility effects on secondary flows

The method of W. R. Hawthorne for the calculation of the secondary vorticity is generalized for compressible flow. It is shown that in the linearized theory (small vorticity) the influence of compressibility upon the secondary vorticity is due to (1) the entropy gradient in the approaching flow and (2) the compression of the fluid during the turning of the flow. The analysis is applied to the secondary vorticity which generates in a cascade or bend if the approaching flow has a boundary layer with a Prandtl Number equal to unity and has been developed along an insulated wall.