ADAPTIVE FEEDBACK CONTROL OF STABILITY IN AN AXIAL FLOW COMPRESSOR WITH CIRCUMFERENTIAL INLET DISTORTION

The adaptive feedback control of stability with circumferential inlet distortion has been experimentally investigated in a low-speed axial compressor. Three flat-baffles with different span heights are used to simulate circumferential distorted cases. Compared with auto-correlation and root-mean-square analysis, cross-correlation analysis used to predict early stall warning does not depend on the circumferential distortion position. Hence, the cross-correlation coefficient was used to monitor the stable status of the compressor when suffering from different circumferential distortions and was also selected as the feedback signal in the active control strategy. Based on the stall margin improvement of tip air injection obtained under different distorted intensities and the sensitivity analysis of cross-correlation coefficients to injected momentum ratios, tip air injection was adopted as the actuator for adaptive feedback control. The designed digital signal processing controller was applied to achieve adaptive feedback control in distorted inflow conditions. Results show that the adaptive feedback control on stability can obtain approximately identical stall margin improvement as the steady injection under different distortion intensities with a reduced injection mass flow. Thus, the proposed adaptive feedback control is ideal for the engine operation with circumferential distorted inflow, which frequently occurs in the flight.