Stability Enhancement Mechanism Study of Vaned Diffuser Recirculation Technique in a Highly Loaded Centrifugal Compressor
Radial diffuser is the key component of high pressure ratio centrifugal compressor.A centrifugal compressor with high pressure ratio was taken as the research object.The self-circulating flow control of the diffuser was studied by using the validated numerical method.Mechanism of the recirculation technique of the diffuser on the performance and internal flow of the centrifugal compressor was discussed in detail.The results showed that the self-circulating flow control has different effects at different rotational speeds.At 100％rotational speed,the stall margin of the centrifugal compressor could be increased by 3.5％.However,the flow control method could not improve the stall margin at off-design speeds.Detailed flow field shows that the flow control method reduces the inlet Mach number of the diffuser,increases the critical angle of attack for separation,and prevents flow separation on the suction side of the diffuser under the near-stall condition of 100％rotational speed by introducing a jet perpendicular to the main flow direction,thus effectively improving the stable operating margin of the centrifugal compressor.
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