Effects of water ingestion on the aerodynamic performance of an axial compressor

Liquid water in the atmosphere affects the safety and stability of aero-engines in their operation and threatens flight safety because when liquid water is ingested by compressors, it breaks into smaller droplets, which then bounce in, collide with, or splash onto the blades of compressors, increasing profile loss and aerodynamic drag. As a result, the performance of compressors would deteriorate after water ingestion. To investigate the mechanisms underlying such performance changes and flow differences within the passage due to water ingestion, we simulate the gas-liquid two-phase flow within National Aeronautics and Space Administration Rotor 67 by employing the Eulerian–Lagrangian approach. This paper investigates water–air ratios ranging from 3% to 9% of the total mass and droplet diameters between 500and 1500 μm. Numerical simulations are used to examine the flow and performance of the compressor under different inlet conditions. The results demonstrate that higher water ingestion rates and smaller droplet diameters decrease the compressor efficiency, due to increased entropy generation. They also reduce the mass flow rate, due to droplet accumulation blocking the passage. Specifically, water droplets reduce the axial velocity and significantly increase boundary layer separation losses on the blade suction surface. In addition, water ingestion partially mitigates tip clearance leakage flow losses, slightly weakens the shock intensity, and shifts the shock position forward, while delivering minimal impact on wake losses.