Numerical analysis on the contributions of flow-induced noise sources in a centrifugal pump

To reveal the contribution of flow-induced noise sources and their spatial distribution characteristics in a centrifugal pump, the broadband noise source model and the acoustic analogy method coupled with large eddy simulation and finite element method are applied to investigate the dipole source and quadrupole source under the nominal condition. The validity of the numerical method is verified through measurements of flow-induced noise. Results demonstrate that the sound power of the dipole source is significantly higher than that of the quadrupole source caused by turbulence and vortices, with the main noise source regions identified as the blade suction side and the spiral section of volute. Flow-induced noise in the frequency domain exhibits a combination of broadband components and discrete components, with the discrete components being the blade passing frequency (fBPF) and its harmonics. The blade dipole source exhibits dense discrete spectrum, with discrete components also including subharmonics of the fBPF. At the inlet and outlet, the contribution of blade dipole to low-frequency noise is significantly greater than the volute dipole. As the frequency increases, the contribution of the volute dipole gradually rises. When the frequency exceeds 20 times the fBPF, the dominant noise component shifts to the volute dipole, a phenomenon that is more pronounced at the outlet. The intensity of noise inside the volute is lower than that at the pump inlet and outlet, with the blade dipole as the dominant source, which exhibits a sound pressure level at the fBPF that even surpasses the total noise.