Abstract: It is crucial to accurately identify where and when stall and surge occur in a centrifugal compressor. A centrifugal compressor with a vaned diffuser is chosen as an experimental object. Based on the multi-phase dynamic pressure measurement technology, the pressure signals at different radial locations, such as the impeller passage, the vaneless space and the diffuser throat, are acquired synchronously at different unstable operating conditions. By changing the angle of the diffuser vanes, the features of stall and surge phenomena at different conditions is obtained. It is analyzed and discussed about how to discern these two typical unsteady flow phenomena, and an index based on chaotic characteristics is proposed which can measure the proportion of deterministic components in the fluctuation of pressure fluctuation caused by stall and surge. It is found that the index can correspond to both the real-time signals and the results of standard deviation analysis. Thus, it can identify the moment and position about the original occurrence of stall and surge more accurately.

Key words: centrifugal compressor, chaotic characteristics, identification, stall, surge