旋回失速発生過程における遠心羽根なしディフューザ内静圧場(流体工学,流体機械)  [in Japanese] Static Pressure Field during Generation Process of Rotating Stall in a Radial Vaneless Diffuser(Fluids Engineering)  [in Japanese]

The operation range of a centrifugal compressor or blower at low flow rate is limited by selfexcited oscillation in the diffuser called rotating stall that causes sudden performance drop. One of the main characteristics of this phenomenon is pressure fluctuation that varies in various patterns. There is a pressure fluctuation even before the onset of rotating stall, which is weak and its intensity is not stable. In this study herein, simultaneous multiple static pressure measurements were held with pressure transducers in entire diffuser at the flow rate just before rotating stall occurred. For analyzing various signal processing methods were used ; continuous wavelet analysis, cross spectrum analysis and phase-locked ensemble-averaging technique. As result, aspects of the pressure field just before the onset of rotating stall is clarified.