Experimental Research on Cavitation-induced Vibration and Noise of Centrifugal Pumps under Variable Flow Rate Conditions

To investigate cavitation-induced vibration and noise characteristics in a centrifugal pump and their correlation with pressure pulsations, experiments were conducted in a semi-anechoic chamber using a closed-loop test rig. Cavitation intensity was regulated by adjusting inlet pressure under four flow conditions. High-speed imaging and synchronous measurements of pressure pulsations, vibration, and acoustic signals were performed, and frequency-domain and coherence analyses were applied. Results show that as NPSHa decreases from ۵.۲ m to ۱.۸ m, cavitation evolves from discrete bubbles at the impeller inlet to large-scale vapour clouds. Pressure pulsation energy is mainly concentrated at the blade-passing frequency (BPF) and its harmonics, distributed across low (<۵۰۰ Hz), mid (۱۵۰۰–۲۵۰۰ Hz), and high (۳۵۰۰–۴۵۰۰ Hz) frequency bands. With increasing cavitation, broadband noise in the mid–high frequency range of the internal sound field increases by ۳–۸ dB, while external noise remains relatively unchanged due to structural attenuation. Vibration responses exhibit distinct BPF peaks and broadband elevation in the mid–high frequency range, attributed to the combined effects of pressure pulsations and bubble collapse. As cavitation develops, bubble dynamics weaken rotor–stator interactions; however, pressure pulsations remain the dominant excitation source of vibration below ۴۰۰۰ Hz.

کلیدواژه ها:

Required net positive suction head ، Rotor-stator interaction ، Blade passing frequency ، Frequency domain analysis ، Coherence analysis