An investigation of surge in a high-speed centrifugal compressor using digital PIV

Compressor stall is a catastrophic breakdown of the flow in a compressor, which can lead to a lass of engine power, large pressure transients in the inlet/nacelle, and engine flameout. The implementation of active or passive strategies for controlling rotating stall and surge cart significantly extend the stable operating range of a compressor without substantially sacrificing performance. It is crucial to identify rite dynamic changes occurring irt the flow field prior to rotating stall and surge in order to control these events successfully. Generally, pressure transducer measurements are made to capture the transient response of a compressor prior to rotating stall. In this investigation, Digital Particle Imaging Velocimetry (DPIV) is used in conjunction with dynamic pressure transducers to capture transient velocity and pressure measurements simultaneously in the nonstationary flow field daring compressor surge. DPIV is an instantaneous, planar measurement technique that is ideally suited for studying transient flow phenomena in high-speed turbomachinery and has been used previously to map the stable operating point flow field in the diffuser of a high-speed centrifugal compressor. Through the acquisition of both DPN images and transient pressure data, the time evolution of the unsteady flow during surge is revealed.