Numerical and Experimental Investigation of Non-Cavitation Noise of Axial Flow Pumps for Various Pump Parameters

Pump-jet propulsion is gaining attention due to its multifunctional operation, strong hydraulic performance, and low noise levels, especially as traditional propulsion systems begin to reach their performance limits. This research combines computational fluid dynamics (CFD) and computational aeroacoustics (CAA) methods, validated through experiments conducted on a custom test equipment. The analysis explores how various factors such as the inlet flow rate, the impeller speed, and the number of blades affect non-cavitating noise in axial flow pumps. It is found that the lower flow rates, especially under off-design conditions, lead to increased overall sound pressure levels (OASPL). For instance, reducing the flow rate by 200 m3/h results in a 2.74 dB increase in OASPL, whereas a 100 m3/h increase in the flow rate causes only a 0.50 dB rise. Additionally, increase in the impeller speed has a more pronounced effect on overall sound pressure levels (OASPL) than decrease. There is also a nonlinear relationship between non-cavitating noise and the number of blades, indicating complex interactions. These results provide essential insights for predicting non-cavitating noise and optimizing acoustic design in the axial flow pumps.