Experimental and numerical investigation of interior flow-induced noise in pump as turbine

Abstract

The flow-induced interior noise in pump as turbine (PAT) consists of flow-borne noise and flow-induced structure noise from dipole source. Without accurate distinguishing of main interior noise, the noise control and management cannot be guided. The experiments of flow-induced interior noise and free modals for rotor and casing were performed to validate the accuracy of numerical methods. The computational models for flow-induced noise and flow-borne noise considering structure in interior acoustic field were developed. On the basis of this, the spectrum characteristics of each noise source and their contribution to the total noise were distinguished. It is found that within interior noise, the radiated energy of flow-induced structure noise is less than that of flow-borne noise generated by dipole source. Compared with the experiment, the flow-borne noise considering structure due to casing source can more precisely reflect joint action of multiple sources. Especially in larger flow conditions, the maximum error is only 5.9 % at Blade-Passing Frequency (BPF) and its harmonics.