Performance deterioration of an aero-engine secondary air system caused by pre-swirl blade erosion

During aero-engine operation, ingested sand and dust particles may enter the secondary air system and cause erosive wear of internal components, thereby degrading flow organization and cooling performance. In this study, an air-system sand-ingestion test rig was established to obtain real eroded pre-swirl blade geometries. Reverse reconstruction of the eroded blades was then conducted based on three-dimensional surface measurements, and numerical simulations were performed to investigate the performance deterioration of the secondary air system induced by blade wear. The results show that erosion is mainly concentrated at the trailing edge of the pre-swirl blade. Mild wear has only a limited influence on overall system performance and may slightly increase the discharge coefficient by weakening local separation and backflow. As wear intensifies, the circumferential flow guiding and pre-swirl capacities of the blade are progressively weakened, leading to deteriorated pressure distribution, poorer flow matching, and significant reductions in discharge coefficient and temperature-drop efficiency. Under the severe wear condition, the discharge coefficient decreases from 0.973 to 0.772, corresponding to a reduction of 20.66%, while the temperature-drop efficiency decreases from 0.248 to 0.188. Rapid performance deterioration occurs when the throat area between adjacent blade passages increases markedly, reaching 1.59 and 1.95 times the original value under PSB-ED4 and PSB-ED5, respectively. Therefore, throat-area variation is identified as a key geometric factor controlling system degradation.