Unsteady rotating stall characteristics in a centrifugal pump with slope volute at low flow rates
Numerical simulation method was used to analyze unsteady rotating stall characteristics in a centrifugal pump with slope volute at low flow rates. Fast Fourier Transform (FFT) was applied to transform time domain pressure signals to frequency domain signals. Results show that: hump phenomenon occurs in head curve of model pump, and pressure distribution at different position of slope volute is not uniform. Flow structure in each impeller channel differs, which is influenced by unsteady effect generated by rotating impeller. At different operating conditions pressure pulsation signals are different leading to variable excitation frequencies existing in pressure spectrum. Working at 0.4ФN condition, 0.5fR and its higher harmonics appear in pressure spectra, and pressure magnitude reaches maximum value at 4fR. At flow rate 0.2ФN, excitation frequencies 0.18fR and its harmonics occur. At 0.05ФN, two different excitation frequencies 0.1fR and 0.28fR appear in pressure spectra induced by unsteady flow structure in impeller channels. Pressure amplitude at blade passing frequency does not keep the predominant role in pressure spectra at rotating stall status.
School of Energy and Power Engineering Jiangsu University, Zhenjiang 212013,China
Abstract：Numerical simulation method was used to analyze unsteady rotating stall characteristics in a centrifugal pump with slope volute at low flow rates. Fast Fourier Transform (FFT) was applied to transform time domain pressure signals to frequency domain signals. Results show that: hump phenomenon occurs in head curve of model pump, and pressure distribution at different position of slope volute is not uniform. Flow structure in each impeller channel differs, which is influenced by unsteady effect generated by rotating impeller. At different operating conditions pressure pulsation signals are different leading to variable excitation frequencies existing in pressure spectrum. Working at 0.4ФN condition, 0.5fR and its higher harmonics appear in pressure spectra, and pressure magnitude reaches maximum value at 4fR. At flow rate 0.2ФN, excitation frequencies 0.18fR and its harmonics occur. At 0.05ФN, two different excitation frequencies 0.1fR and 0.28fR appear in pressure spectra induced by unsteady flow structure in impeller channels. Pressure amplitude at blade passing frequency does not keep the predominant role in pressure spectra at rotating stall status.
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