Influence of inlet distortion on stall inception in supercritical CO2 compressor

This study utilizes full-annulus unsteady numerical simulations to investigate the impact of inlet total temperature distortion and total pressure distortion on the performance and internal flow characteristics of a 315 kW supercritical carbon dioxide centrifugal compressor. The results demonstrate a significant performance degradation under distorted inlet conditions. At the design mass flow rate, total temperature distortion and total pressure distortion reduce the total pressure ratio by 1.9% and 0.8%, and decrease the isentropic efficiency by 2.2% and 1.4%, respectively. A severe efficiency drop of 11.1% was observed for the total temperature distortion case at a high mass flow rate. The pressure wave propagates faster than the temperature wave, revealing a significant coupling effect between temperature and pressure. The loss distribution is asymmetric: under total pressure distortion, losses are primarily concentrated in the tip leakage region, whereas total temperature distortion induces significant losses due to hub-side friction and flow separation. Furthermore,1 compared to total pressure distortion, total temperature distortion increases the mixing loss in the vaneless diffuser by 25% and triggers an earlier onset of impeller stall, thereby altering the stall evolution path. This research elucidates the underlying flow loss mechanisms and stall behavior in a supercritical carbon dioxide compressor under inlet distortion, providing a theoretical basis for enhancing its operational stability and optimizing performance.