Abstract

Rotating stall is an unsteady flow phenomenon, which always leads to instability and efficiency degradation. In order to reveal pressure fluctuations in the impeller of centrifugal pump induced by stall cells, the flow structures in a volute-type centrifugal pump were calculated using Large Eddy Simulation (LES) method. The predicted results of the numerical model were compared with experimental flow-head curve. The simulation results were in good agreement with the experimental results. The stall phenomenon occurred when the flow rate dropped to 70% of design flow rate. Three stall cells located at the entrance of passages could be observed, which remained stationary relative to the rotating impeller. With the decrease of flow rate, the area occupied by stall cells gradually increased. The peak value of pressure fluctuation at 25% of design flow rate is obviously larger than that at 50% of design flow rate. For the unstalled or stalled passage, the impeller-volute interaction played a leading role in the pressure fluctuations of the impeller. For the stalled passage, the amplitude of the low frequency induced by stall cell is relatively insignificant.

Highlights

  • Centrifugal pumps play a key role in the industry, irrigation, and water supply engineering

  • At low flow rates, this axisymmetric flow field would be destroyed, and some rare pressure fluctuations excited by stall cells appear

  • Under stall conditions, pressure fluctuations of centrifugal pump resulted from the combined effect of stall cells and impeller-volute interaction

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Summary

Introduction

Centrifugal pumps play a key role in the industry, irrigation, and water supply engineering. At low flow rates, this axisymmetric flow field would be destroyed, and some rare pressure fluctuations excited by stall cells appear. It always induces intensified vibration, enhanced noise, and decreased capacity of water supply, which seriously affects the safe and stable operation of the pump system [1,2,3]. Under stall conditions, pressure fluctuations of centrifugal pump resulted from the combined effect of stall cells and impeller-volute interaction. This study focuses on the impeller-volute interaction under stall conditions around the tongue district, providing a reference for stable operation of centrifugal pump units

The Investigated Pump and Simulation Details
Unstructured
Prediction
Instantaneous
Unsteady Behavior of Stall Cells
Analysis of Pressure Fluctuations in the Impeller
Analysis
Findings
12. Frequency

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