Assessment of Noise Signature for a Cavitating Centrifugal Pump

Abstract

In recent days, sophisticated instruments have emerged to obtain an online measurement of performance parameters from centrifugal pump of different kinds and the signals can be directed to the hands of pump users through mobile applications. With this in mind, a centrifugal pump of low specific speed was chosen for cavitation studies from 80% to 120% of nominal flowrate and for three different speeds. An assessment was carried out for cavitation noise signature from those operating conditions of that pump. The result of cavitation noise based on peak magnitude as well as average revealed nature in relation to cavitation coefficient, and it greatly depends on the flowrate with respect to nominal flowrate. The noise envelope for the flowrate at best efficiency and above was having a similar trend whereas at flows less than the nominal, it was totally different. So the criteria for finding the deviation in noise cannot be uniform for all flowrates. In this paper, the method adapted was to impose a trend line to the measured cavitation noise information and to find out the deviation with respect to normal operating conditions. It was concluded that detection of abnormality in pumps due to cavitation effects requires the current operating condition to be diagnosed first and then proper criteria for deviation in noise has to be imposed.