Effects of Flow Loss and Inlet Distortions Caused by Radial Inlet on the Performance of Centrifugal Compressor Stage

Radial inlet is a typical upstream component in centrifugal compressors. Compared to axial inlet, radial inlet generates additional flow loss and introduces inlet distortions to the impeller inlet, which negatively impacts the performance of the whole centrifugal compressor. In this paper, two centrifugal compressor stages with different radial inlets were investigated with numerical simulations. Three computational models, (i) with radial inlet (ii) without flow loss and inlet distortions (iii) with flow loss but no inlet distortions, were built for each compressor stage, and calculations were carried out to analyze the respective effects of flow loss and inlet distortions caused by radial inlet on the performances of the compressor stage and the downstream components. The present study validates that flow loss and inlet distortions caused by radial inlet are the main factors by means of which the radial inlet affects the performance of the centrifugal compressor. What’s more, the results indicate that flow loss in radial inlet only affects the performance of the whole radial inlet stage, but has little effect on the downstream components such as the impeller; while inlet distortions caused by radial inlet not only negatively influence the performance of the whole radial inlet stage, but also have significant effects on the downstream components. This research, as a preliminary work of the improvement study, provides references for the structure modifications of radial inlet in the next stage.