Effect of vaned diffuser on performance and onset of pressure instabilities in centrifugal compressor

The paper presents the results of an experimental investigation of the effect of the straight-channel diffuser vanes in centrifugal compressor on stability, range and quality of unit operation, at different speeds and flow rates. Comparison of the performance of the same impeller, which was coupled first with a vaneless diffuser and next with a vaned one of the same global geometry, shows operating maps, static pressures along the flow path inside the unit, excitations generated inside the impeller and diffuser system and, finally, propagation of these excitations in the inlet and discharge compressor piping. Laboratory findings were confirmed in field conditions, where the removal of the diffuser vanes in compressor station units resulted in vibration mitigation and performance improvement.