Numerical investigations of circumferential nonuniformity and model refinement under inlet distortion effects

The inlet distortion issue in propulsion systems leads to a degradation of compressor performance and induces aerodynamic instability. To assess the impact of total pressure distortion on performance and stability, a parallel compressor modeling study and three-dimensional unsteady numerical simulations were conducted using a single-stage compressor as the research subject. The results show that, under the influence of inlet distortion, the internal three-dimensional flow field of the compressor exhibits significant circumferential non-uniformity. The limitations of the parallel compressor modeling assumptions affected the prediction accuracy, the classic model shows greater computational errors in the low mass flow rate region of the characteristic map. Specifically, for near stall condition, the relative error in corrected mass flow rate is 2.67%, with the relative error in total pressure ratio being 1.27%, consequently leading to a relative error of 48.31% in the stability margin. By analyzing the flow field data under distorted conditions, the classic model was modified, using a circumferential displacement model for the affected region and a non-uniform static pressure distribution model at the stator outlet. The modified model aligns well with the characteristic map obtained from numerical simulations, with relative errors of performance parameters not exceeding 1% under two typical operating conditions and the relative error in stability margin is 3.77%. In addition, the model was validated on another transonic compressor, where the relative errors in corrected mass flow rate and total pressure ratio under two conditions were both less than 2% compared to experimental/numerical simulation results.