Numerical study of the effect of guide vanes on hydraulic turbine noise

In order to study the effect of the guide vane on the internal and external acoustic fields of a centrifugal pump operating in turbine mode, a single-stage, single-suction centrifugal pump with a specific speed of 84.5 is selected as the research object. ANSYS Fluent numerical simulation and the acoustic boundary element/finite element (ABEM/FEM) method are employed to calculate the flow field and sound field of the centrifugal pump operating as a hydraulic turbine, respectively. The results indicate that in the internal sound field, the addition of the guide vane has a greater influence on the sound pressure level at the inlet than at the outlet. At the first lobe frequency, the guide vane significantly affects the inlet sound pressure level, with the most noticeable reduction of 1.2 dB occurring under optimal operating conditions. The impact on the outlet is relatively smaller, and the reduction in sound pressure level gradually decreases as the flow rate increases. Regarding the external sound field, the maximum sound pressure levels occur near the inlet, outlet, tongue, and base. The sound pressure level distribution exhibits dipole source characteristics, and the reduction is more pronounced under optimal operating conditions. After adding the guide vane, the external sound field's plane radiation value is significantly reduced compared to the original model in areas with high sound pressure levels. This study provides theoretical references for future noise reduction efforts in hydraulic turbines.