Flow Analysis of Rotating Stall in Centrifugal Pump

Abstract

Numerical simulation is carried out to understand the effect of impeller exit width on centrifugal pump rise, rotating stall progression and oscillation frequency with variation in flow coefficient. Steady and transient flow simulations of centrifugal pump were carried out for different flow rates. A comparative analysis of simulation results shows different degree of rotating stall happening in the pump impeller, which is quantified in terms of number of impeller blade passage affected by stall. Pressure fluctuations at different locations were compared with the test data and oscillation amplitude determined for different mass flow rates. Effect of rotational speed on pressure oscillation is also determined by varying rotor speed. Analysis shows that oscillation frequency is increasing with increased rotational speed and also depends on the rate at which stall bubbles travels through the clearance of impeller and diffuser. Transient analysis shows that these stall regions are rotating at frequency ranging from 11% to 12% of rotor speed.