Unsteady Pressure Pulsation and Rotating Stall Characteristics in a Centrifugal Pump with Slope Volute

Abstract

Unsteady flow structures can lead to severe vibration in centrifugal pump if the eigenfrequency of the rotor is equal to excitation frequency. In order to reduce rotor-stator interaction in centrifugal pump, a special slope volute was proposed. This paper explores the use of numerical simulation method to illustrate unsteady pressure pulsation and rotating stall characteristics under 0.05Φ -1.4Φ working conditions. Spectrums of pressure pulsation signals at different flow rates were analyzed. Relative velocity distributions interior blade channels were also studied to clarify correlation between flow structure and pressure spectrum. At high flow rates, predominant components in pressure spectrums always correspond to blade passing frequency ( BPF ). With decreasing of flow rate, partial flow separates from suction side of blade at 0.6Φ , but the separate structure has little impact on pressure spectrum. From 0.8Φ to 0.6Φ , peak values in pressure spectrums are still located at BPF . At rotating stall working conditions, multiple vortex structures exist in impeller, which develop with rotating impeller showing intensive unsteady properties. And partial blade channels are blocked severely. Due to the unsteady stall cell structure, stall frequencies are generated in pressure spectrum, and the excitation frequencies are different at variable flow rates.

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