Improving the reliability of centrifugal compressor operation requires accurate acquisition of time-frequency characteristics. Based on the dynamic pressure data acquired at the impeller outlet when the high-speed centrifugal compressor with vaneless diffuser approached the unsteady condition

spatiotemporal intrinsic mode decomposition (STIMD) and empirical mode decomposition (EMD) were used to obtain the intrinsic mode functions (IMF). Combining Hilbert transform

the dynamic characteristics of unsteady flow were analyzed. By STIMD algorithm

the time-frequency information of deep surge and mild surge was obtained. The phenomenon of stall with continuous fluctuation frequency around 150 Hz was observed

whilst the transition of frequency curve of mild surge precursor from oscillating to constant state was found. STIMD algorithm has improved the modal aliasing problem of EMD

thus providing a tool for compressor stability analysis.