Experimental and numerical investigations on the flow-induced vibration and acoustic radiation of a pump-jet propulsor model in a water tunnel

Abstract

Experimentally investigating the vibration characteristics of a pump-jet propulsor in water is challenging. In this study, the characteristics of flow-induced vibration and acoustic radiation of a pump-jet operating in a water tunnel were experimentally and numerically investigated. A customised vibration acceleration acquisition instrument was used to measure the vibration response of the rotor. Numerical simulation methods are established based on Computational Fluid Dynamics (CFD), coupled Finite Element Method (FEM), and Boundary Element Method (BEM). The CFD model, verified by the hydrodynamic performance, was used to numerically investigate the fluctuation pressure and unsteady forces of the pump-jet. The coupled FEM model verified by the rotor mode and BEM model was used to calculate the flow-induced vibration response under distributed unsteady forces and acoustic radiation, respectively. The results show that the vibration response of the rotor has prominent peaks at Shaft Frequency (SF) and Blade Passing Frequency (BPF) for the experimental and coupled FEM results. The inadequate cancellations of the spatial distribution and phase distribution of the unsteady rotor forces contributed to the high amplitude at SF, in addition to the rotor–shaft system imbalance. The Sound Pressure Level (SPL) after the superposition was maximal at BPF and had a relatively high amplitude at SF, in agreement with the experimental results. The established simulation method can reasonably obtain the characteristics of flow-induced vibration and acoustic radiation of the pump-jet and demonstrates a similar variational trend as the experimental results.