Experimental Investigation of the Effect of Air Injection on Performance and Detection of Cavitation in the Centrifugal Pump Based on Vibration Technique

Cavitation is a problem that occurs in any pump and contributes highly towards the deterioration in the performance of the pump. In industrial applications, it is vital to detect and minimize the effect of cavitation in pumps. The use of various techniques, such as vibration analyses, can provide a more robust detection of cavitation in the pump. In this work, the effect of air injection at the inlet of the pump on its performance has been focused by detecting and diagnosing the cavitation using vibration technique. The results obtained for vibration signal in time and frequency domains were analysed in order to achieve a better understanding regarding detection of cavitation. The effects of different operating conditions related to the cavitation were investigated in this work using different statistical features in time domain. Moreover, fast Fourier transform technique for frequency domain was also applied. The results showed that there is no significant change between both cases (with and without air injection) when the pump works under low flow operating conditions. However, there is a slight difference between both cases after 300(l/min) and drop in the pump head for air injection was noticed as compared to without air injection condition. Moreover, the development of cavitation starts at higher design flow and it will increase when flow rate is increased more than 350(l/min). The trend of vibration signal amplitude was more random with high peaks when compared with normal operating conditions (without cavitation).