Acoustic distribution study inside centrifugal pump impeller under different blade outlet angles using the Powell vortex sound theory

Abstract

The acoustic distribution characteristics inside centrifugal pump impeller under different blade outlet angles are explored based on the Powell vortex sound theory. It is shown that the increase in the blade outlet angle narrows the fluctuation ranges of the acoustic source and acoustic pressure perturbation at the impeller outlet far away from the tongue, while extends those near the tongue. The total acoustic source intensity and total acoustic pressure level at the impeller outlet far away from the tongue decrease by 1.23% and 1.17%, respectively, while those near the tongue increase by 0.64% and 0.94% when the angle increases from 15° to 35°, respectively. Additionally, under different blade outlet angles, the total acoustic source intensity and total acoustic pressure level on the streamline far away from the tongue increase rapidly first, then increase slowly from inlet to outlet of the impeller. On the streamline near the tongue, a mutation of total acoustic source intensity and total acoustic pressure level appears near the impeller outlet, and the mutation range moves towards the middle section of the impeller with increasing blade outlet angle and rotational speed. In addition, the A-weighted average acoustic source intensity level and A-weighted average acoustic pressure level increase by 0.4% and 1.22% when the angle increases from 15° to 35°, respectively. The study reveals the rotor–stator interaction intensity evolution characteristics, and provides a reference for the optimization design of centrifugal pumps.