The pump performance and occurrence of cavitation directly depends on different operating conditions. To cover a wide range of operation conditions for detecting cavitation in this work, investigations on the effect of various suction valve openings on cavitation in the pump were carried out. In order to analyse various levels of cavitation in different operation conditions, the effect of the decrease in the inlet suction pressure of the centrifugal pump by controlling the inlet suction valve opening was investigated using this experimental setup. Hence, the acoustic and pressure signals under different inlet valve openings and different flow rates, namely, 103, 200, 302 l/min were collected for this purpose. A detailed analysis of the results obtained from the acoustic signal was carried out to predict cavitation in the pump under different operating conditions. Also, the acoustic signal was investigated in time domain through the use of the same statistical features. The FFT technique was used to analyse the acoustic signal in the frequency domain. In addition, in this work an attempt was made to find a relationship between the cavitation and noise characteristics using the acoustic technique for identifying cavitation within a pump.
Centrifugal pumps are used for different applications that include pressure boosting, wastewater, water supply, heating and cooling distribution and other industrial processes. This paper presents theoretical and experimental investigations of mechanical vibrations of a centrifugal pump. The flow in this pump, which induces pressure pulsations and mechanical vibrations, have been monitored. Vibration measurements and data collection (overall vibrations levels and frequency spectrum) were extracted from the system. In addition, one of the methods used to study vibration amplitudes for this pump is forced response analysis. To study and analyze the pump system, the finite element analysis software (ANSYS) was applied. Depending on the analysis performed and investigations outcomes, the system natural frequency coincides with the vane-pass frequency (VPF) hazardously. To attenuate the system’s vibration, a vibration control element was used. The vibration levels were reduced by a factor of 2 for a tuned element as obtained from a forced harmonic response analysis of the pump system with absorber. It is shown that the inserted element allows the centrifugal pump to work in a safe operating range without any interference with its operation.
The small number of available complete modern pump characteristics makes the safety analysis of nuclear and conventional power plants based on the characteristics made over half a century ago of specific speeds n_q=24.6, 147.1 and 261.4. The aim of the paper is to check sensitivity of the power plant system response for different complete pump characteristics - modern and available from older tests for n_q=24.6, 147.1 and 261.4. It has been shown that Suter's characteristics for modern pumps give a different response to the pumping system of a power plant in breakdown than those used so far.