Research on aerodynamic characteristics and flow mechanisms of axial compressors under rain ingestion

Abstract To investigate the effects of rainfall on the aerodynamic performance and internal flow of transonic compressors, this study focuses on the NASA Stage 35 single-stage axial compressor. Using an Euler-Lagrange multiphase flow approach, the analysis accounts for both droplet aerodynamic breakup and evaporation effects. Aerodynamic performance and spatial flow fields were evaluated under dry conditions at 70 % of the design speed and wet conditions with varying water contents (3 %, 6 %, and 9 %). The results indicate that, in terms of compression performance, rainfall generally reduces the total pressure ratio and isentropic efficiency of the compressor while narrowing the stable operating range. Near-stall conditions show that droplet evaporation mitigates the rise in total temperature. Regarding the internal flow, momentum exchange between phases weakens the main flow acceleration and pressurization, leading to noticeable decreases in total pressure and axial velocity in the mid-to-upper blade height regions, thereby intensifying radial non-uniformity. Locally, droplet breakup and dispersion increase entropy generation, especially near the blade tip, enhancing mixing losses. Furthermore, the supersonic region on the suction side at 50 % span expands and the relative Mach number increases, altering the transonic flow field structure.