A Theoretical Investigation of Transonic Flows in Radial Compressor Diffusers

The transonic flow in a diffuser of a centrifugal compressor with high pressure ratio has been analyzed by a numerical procedure. The method consists of an inviscid calculation of the pressure field in the vaned diffuser and of a determination of the boundary layer flow along the blades. The diffuser has been equipped with curved vanes, and only the flow through one channel is considered. The two-dimensional pressure distribution has been calculated by a time-dependent finite difference scheme. The boundary layer flow has been determined by different integral methods with special attention concerning the shock-boundary-layer interaction. Finally, the numerical results are compared with experiments, and the agreement is satisfactory.