Adaptive Stability Control of a High-Speed Axial Flow Fan under Circumferential Distortion Inlet Conditions

Abstract Adaptive stability control is experimentally studied in a high-speed axial flow fan of an aero-engine under circumferential distortion conditions. A baffle is used to simulate circumferentially distorted inflow with a comprehensive distortion index of 9%. Experimental results indicate that distorted inflow leads to compressor performance degradation and reduces stall margin by 8.81% at design speed. To mitigate this effect, an adaptive stability control system is devised. Although distorted inflow alters the instability route, cross-correlation analysis can be validated for early stall warning and serve as the feedback signal via casing wall pressure sensors. Tip air injection mitigates the forward movement of the leading-edge shock wave and tip leakage vortex downstream of distortion region, thereby delaying stall onset. Moreover, tip air injection increases the correlation coefficient, enabling a correlation between stability-enhancing parameter and stall warning signal. In adaptive control experiments, once the warning threshold is triggered, the feedback signal regulates the proportional valve opening, and tip air injection is activated to delay stall occurrence. Under circumferentially distorted inflow, the strategy improves SM by 8.45% and 9.31% at 100% and 80% design speed, respectively, without peak-efficiency penalty. The improvement is comparable to steady injection with constant mass flow, while injection energy consumption is reduced by approximately 40%. This study verifies the feasibility of the adaptive stability control strategy based on cross-correlation algorithms and tip air injection for high-speed axial compressors under distorted inflow conditions, and offers a reference for engineering applications.