Comprehensive Loss Assessment of Compressor Design Space for Axial, Mixed-Flow, and Centrifugal Topologies

Abstract

Accurate loss prediction is essential throughout the turbomachinery design process, from preliminary meanline calculations to detailed optimisation. This paper compares loss breakdowns across compressor topologies and supplements traditional design charts with a loss assessment based on flow features such as the shock criterion, streamwise vorticity, and velocity gradients. This study therefore extends a phenomenological loss decomposition approach to axial, mixed-flow, and centrifugal compressors. Loss breakdowns are evaluated across a broad design space, which is defined by the flow coefficient, the loading coefficient, the HTR, the inlet Mach number, and the Reynolds number. These breakdowns are then evaluated within a Smith chart to reveal topology-dependent trends. The results show that loss distributions vary significantly within the design chart and between compressor types. The proportions of secondary flow losses increase towards lower flow coefficients in axial and mixed-flow compressors, but towards lower loading coefficients in centrifugal machines. As radiality increases, secondary flow losses rise while profile losses diminish. Endwall losses mainly increase towards large flow and small loading coefficients in axial and mixed-flow compressors, but towards high loading in centrifugal compressors. In axial and mixed-flow compressors, variations in the HTR redistribute losses in opposite directions between the hub and the tip. The effect of an increase in the Reynolds number varies significantly between centrifugal and axial compressors. High inlet Mach numbers amplify secondary flow losses in all compressors. While profile losses are becoming more pronounced in axial compressors, no systematic trend has been identified in centrifugal compressors.