The onset of rotating stall has been delayed in a low-speed, single-stage, axial research compressor using active feedback control. Control was implemented using a circumferential array of hot wires to sense propagating waves of axial velocity upstream of the compressor. Using this information, additional circumferentially traveling waves were then generated with appropriate phase and amplitude by “wiggling” inlet guide vanes driven by individual actuators. The control scheme considered the wave pattern in terms of the individual spatial Fourier components. A simple proportional control law was implemented for each harmonic. Control of the first spatial harmonic yielded an 11 percent decrease in the stalling mass flow, while control of the first, second, and third harmonics together reduced the stalling mass flow by 23 percent. The control system was also used to measure the sine wave response of the compressor, which exhibited behavior similar to that of a second-order system.

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