The Optimization of Flow-Induced Noise Under BPF by Changing the Impeller Diameter

With the widely application of IS series centrifugal pumps in industry and agriculture, the blade-passing frequency (BPF) flow-induced noise in these pumps are tend to be optimized. In this paper, a common type IS50-65-160 is chosen as the model pump to do the optimization of BPF noise. Considering both the effect of noise reduction and applicability of the project, an optimization scheme of cutting the impeller diameter is proposed. An analysis of the different performance curves, corresponding to different impeller diameters, emerges the diameter optimization range of impeller from 0.95Dd to 1.0Dd. And two optimal schemes, cutting impeller diameter by 2.5% and 5%, are taken through the comparison with experimental results. Then properties of this BPF noise are predicted by a hybrid method through ANSYS-CFX and LMS Virtual. Lab Acoustics. The result shows that the dipole source is the main flow-induced noise in low specific speed pump, so only dipole source is considered in the simulation. And the sound pressure distributions on monitoring points of these two suggested schemes are calculated and compared with the design impeller. The comparison shows that the optimal scheme is to cut the impeller diameter by 2.5%, while a further cut (0.975Dd) would lead to a much greater loss in head and the noise control effect is not better than cutting by 2.5%.