Experimental study on radiated noise characteristics of multi-stage centrifugal pump under variable speed condition

Abstract

Radiated noise is unavoidable in the operation of multistage centrifugal pumps. In order to study the characteristics of radiated noise of multistage centrifugal pump, radiated noise test system of multistage centrifugal pump was built. Radiated noise experiments were carried out for a medium specific speed multistage centrifugal pump and its modification, which was devised with a new hydraulic design method in the field of sound optimization. The experiment validation on the sound field was performed in a semi-anechoic room and the acoustic parameters of the multistage pump at the different flow rates were gathered with the LMS system(a complete set of solutions for vibration and noise test). The results show that: As the speed is lower than the rated speed, the sound pressure level (SPL) of the radiated noise of centrifugal pump increases with the increase of rotating speed. And the radiated noise of multistage pump rises linearly with the increase of rotating speed. The maximum value of sound pressure level appears around the first stage and the minimum value appears around the middle stage at different flow rates. As the flow rate increases, SPL measured around vane diffuser increases and then decreases. In addition, discrete noise occupies the dominant position in the form of noise for both pumps at large flow rate. Compared with the prototype pump, the intensity of radiated noise of the modified pump weakens in varying degrees in the range of the whole variable speed. Furthermore, the radiated noise exhibits a dipole characteristic at low rotating speed.