Experimental Investigations of Centrifugal Compressor Surge Noise

Abstract

Surge is a crucial problem for achieving a good working range of a centrifugal compressor and power cycle safety. Effective and early detection of surge inception is essential to predict and avoid the onset of it. In this paper, experiments have been conducted to investigate the pressure and acoustic characteristics of the centrifugal compressor surge. The compressor prototype used the research consists of an impeller wheel having backward blades, a vaneless diffuser, and a downstream volute constitute. The compressor prototype was instrumented with steady sensors to characterize the performance map, a fast dynamic pressure sensor to measure the surge-induced pressure fluctuation, and thirteen microphones to record the acoustic pressure on the inlet wall and in far field. The transient experimental data were analyzed in time and frequency domains. The surging noise is identified as a chord sound from multiple sources that radiate acoustic impulse synchronously at the compression system surge frequency (below 10 Hz in the current experiment). A previously rarely discussed surge inception is identified from the acoustic spectrogram within the frequency range of 30-85Hz, in which increase of the SPL is detected before the mass flow rate achieves the surge point. The pressure fluctuation corresponding to the inception is too weak to be captured by the normally used dynamic pressure sensors. It suggests that the acoustic measurement may have advantages in surge inception detection and surge prediction.