Stall Warning and Adaptive Control Subjected to Rotating Inlet Distortion in Axial Flow Compressor

Abstract

Abstract Adaptive stability control is experimentally performed in a single-stage axial flow compressor with rotating inlet distortion. The stall margin variations are obtained as a function of the distorted area and rotating speed, and a critical minimum value exists when the distorted sector rotates at positive 0.5 times the rotor speed (P0.5RS), which is independent of the single distorted area and induced frequency. Unsteady pressure measurements show that for the rotating inlet distortion with P0.5RS, the circumferentially propagating speed of the stall cell induced downstream of the distorted region approximates to the rotating speed of the distorted sector, which causes the stall cell to pass through repeated periods of generation, circumferential propagation, decay, and re-generation, before finally triggering the deep stall in advance as the disturbance energy accumulates. Meanwhile, tip air injection can suppress repeated periodic disturbance energy accumulation, thereby delaying stall. On the premise of successfully verifying the early stall warning under rotating inlet distortion based on cross-correlation analysis, an adaptive stability control strategy is devised to sense the stall warning signal in real time and feed back the signal to control the injected valve once the alarm line is triggering. Even under the rotating distorted inflow with P0.5RS, the stall margin can be on-line improved by more than 10% while affording reducing the injected energy by 80% compared with steady injection. It provides guidance for eliminating the adverse effect of rotating distortion on the compressor performance in multi-spool aero-engines.