Noise analysis in the centrifugal pump based on vortex sound theory with vorticity binary decomposition

This paper aims to analyze the sound and pseudo-sound generation mechanism and its corresponding control method in a centrifugal pump. The delayed detached eddy simulation and vortex sound theory are applied to calculate the flow and acoustic fields. The prediction results agree well with the experimental results. Based on the vorticity binary decomposition, the influence of vorticity and its components of rigid vorticity and shear on the sound and pseudo-sound fluctuation is discussed. The results show that the sound source is dominated by the shearing part rather than rigid vorticity. Sound and pseudo-sound pressure levels could be amplified when the fluctuation of vorticity and its components gets intense, but the pseudo-sound is less sensitive. The amplitude of sound pressure is threefold over the pseudo-sound in the spiral casing, while the pseudo-sound becomes higher than the sound at the outlet as the former decay slowly along the outlet tube. Increasing the volute tongue angle could reduce the fluctuation of vorticity and its components in the outlet tube, leading to a decrease in as much as 44% in sound pressure amplitude and 10% in pseudo-sound.