Numerical investigation was carried out to study the inlet guide vane (IGV) and impeller interaction in a transonic centrifugal compressor.Three blade-row gaps and two rotor/stator(R/S) location settings for each gap model were included in the simulations.The results show that

the R/S location greatly affects the steady calculation performance

but has little effect on the unsteady performance.The IGV-impeller gap barely influences the compressor stage performance

but small gap leads to large pressure pulsation inside the flow field.The existence of impeller shock increases the influence of impeller to IGV several times

even dozens of times for IGV to impeller.And

the formation of pressure pulsation on the IGV pressure and suction side is different due to impeller shock.