Paper 12: Generation of Hydraulic Noise in Centrifugal Pumps

Abstract

The production of hydraulic noise by two types of centrifugal pumps—volute pumps and diffuser pumps—was examined to determine the effect of design and operating conditions on the level of noise generated in the pumped liquid. Experimental work with hydrophones in the exit and entrance to the pumps showed that for both pumps, the dominant frequencies in the noise spectrum were at rotational speed and blade number times rotational speed. It was also found that the distance between cutwater and impeller tip is critical in a volute pump as far as blade frequency noise is concerned. Analysis of the relation between the noise measured by the hydrophones and the fluctuating pressure produced by the pump and the water flow in the inlet and outlet ducts showed that the noise can be interpreted as being directly related to the unsteady flow of water issuing from the impeller. Test results of blade frequency noise levels were correlated with a theoretical analysis for static pressure fluctuations in the pump exit and were shown to be in good agreement. A correlation of general hydraulic noise level with pump specific speed and power consumption was also developed and shown to be reliable to within +2 dB.