Unsteady Aerodynamics of a Centrifugal Compressor Stage: Validation of Two Different CFD Solvers

The unsteady flow field of a centrifugal compressor stage with vaned diffuser has been numerically investigated. Three dimensional steady as well as unsteady numerical simulations have been carried out with the CFD programs Numeca and OpenFOAM. The investigated numerical approaches range from a steady state mixing-plane simulation to an unsteady full annulus 360° computation. The numerical investigation was done at 80% design speed with the Spalart-Allmaras as well as the k-w SST turbulence model. All numerical simulations were compared to the experiments in the compressor map. The velocity field of one operating point near the surge line was analysed in more detail. Similarities and differences between numerical and experimental results are discussed and their causes and effects pointed out.