Circumferential propagation characteristics of initial surge wave in a centrifugal compressor

Surge waves are commonly modeled as one-dimensional plane waves in the understanding of compressor surge. However, this assumption does not adequately represent the physical phenomena observed under specific conditions. This study performed surge experiments on a centrifugal compressor, measuring pressure changes around surge onset with fast dynamic pressure transducers arranged at the same impeller inlet section but at different circumferential positions. The pressure signals are analyzed by the Hilbert–Huang transform, the ensemble empirical mode decomposition method, and the phase locking value concept. With them, instantaneous phase information was extracted, surge signal components were successfully isolated, and non-zero phase differences were identified. Those results demonstrate that surge waves exhibit significant circumferential propagation characteristics, challenging the conventional one-dimensional plane wave assumption. The proposed analytical approach was further validated with experimental data from two pressure-field microphones in an axial compressor experimental setup, thus confirming its validity in analyzing surge waves and the correctness of conclusions drawn from the centrifugal compressor. In conclusion, the novelty of this study is to offer experimental evidence and theoretical insights into the non-axially symmetric propagation of surge waves and an understanding of the fluid physics underlying compressor surge.