Active control of surge in an aircraft compressor

This paper describes the design of an active controller for an aircraft compressor to suppress compressor surge in the unstable operating region at high speed. A high order nonlinear model was linearised at several steady-state points and a set of LQR controllers were derived from these points to schedule the LQR controllers to minimise the bleed mass flow of the compressor stages. In this study, a multi-actuator bleed strategy has been developed to enable the results to be compared with a single-actuator configuration. The results obtained indicate that consumption of the bleed mass flow in a multi-input configuration is less than the bleed mass flow consumed in a single-input system. Results are presented to show that the nonlinear properties of the compressor can be controlled by the application of gain scheduling to a set of LQR controllers and that the compressor can be controlled in the unstable region beyond the surge line with a small bleed mass flow. Using a rigorous nonlinear model written in ACSL, based on data from an actual compressor, it is shown that the control of surge in multi-stage compressors at high speed is feasible.