Study of Flow Induced Noise in Vertical Inline Pump Using Lighthill Analogy

Abstract

The pump user demands for specification along with noise and vibration magnitude for extreme operating conditions apart from best efficiency flow. In order to predict the noise level in pumps, the entire unit of pump has to be considered for acoustic evaluation. Hence, the full three dimensional model of vertical inline pump which consists of inlet pipe, impeller, and volute casing is considered for detailing the flow induced noise using Lighthill analogy. The performance characteristics of pump are well matched between experimental and computational results and the overall sound power level at best efficiency flow using computation was compared with empirical relations and found to be agreed well. The streamline patterns along the inlet pipe shows the effects of recirculation and return flow at partload condition and confirm that the utilization of flow passage is not well streamlined even for nominal flow rate. Further, the detailed study of inlet pipe cross sections reveals the nature of different noise sources such as dipole and quadrupole sound levels along with Proudman source power level. The intensity of turbulence and vortices in flow passage is predicted well using quadrupole source and Proudman sound power levels.