Active Control of Aeroelasticity and Internal Flows in Turbomachinery

Abstract : The research conducted was focused in two areas. The first is active control of rotating stall when inlet distortion is present. This research was carried out on the low speed 3-stage active control research compressor at MIT=GTL. The second area of research was active control of surge in centrifugal and axi-centrifugal engines. Stabilization of such engines beyond their normal stability boundary requires control of 1D oscillations which lead to surge rather than the higher dimensional oscillations which lead to rotating stall. Typically surge control alone allows uncontrolled rotating stall modes to go unstable, which would be debilitating (and probably eventually lead to surge) in an axial compression system. Rotating stall in centrifugal compressors, however, is quite different. If one can prevent surge in a centrifugal machine, rotating stall causing gradual, recoverable performance degradation of the compressor. Thus active control of surge alone can increase engine operating range in engines containing centrifugal compressors.