Impact of Tongue Shapes on Hydraulic and Structure Performances of Double-Channel Pump Based on Fluid-Structure Interaction

The volute tongue has a great influence on the rotational impeller and stationary volute interaction in a pump. In this paper, the impact of tongue shapes on hydraulic and structural performances of a double channel pump with a specific speed of 110.9 is investigated, and four cases with different tongue shapes are simulated by the two-way coupling fluid-structure interaction (FSI) method. The result shows that, in the hydraulic performance aspect, the influence of tongue shapes on the efficiency is weak, and the maximum different value is 0.76%. But the maximum different value of pump-head is 0.126m. Tongue shapes mainly affect the pressure fluctuation in and after the tongue edge in the rotational direction. Pressure fluctuation near the rectangle tongue is stronger than that near the rounded tongue, and an appropriate increase of the corner radius will decrease the pressure fluctuation effectively. Because of the asymmetry of the volute, radial force on the volute is very large. It is periodical when the impeller rotates one circle and decreases obviously with an appropriate increase of the corner radius. Compared to the rounded tongue, the radial force on the volute with rectangle tongue is larger. In structural performance aspect, stress concentration of the impeller appears on the suction surface near the outlet, and the volute stress concentration appears near the tongue edge. Tongue shapes have little effect on the stress distribution of the impeller, but affect the volute stress deeply. The maximum stress near the rectangle tongue is a little larger than that near the rounded tongue, but an appropriate increase of the corner radius will decrease the maximum stress of volute obviously, and the amplitude will decrease slightly. Displacement with the magnitude 10⁻⁵ m happens in the pump, and the maximum displacement point appears in the outlet of the volute. It is periodical and mainly influenced by the blade-passing frequency. The tongue shape has little impact on the maximum displacement, but it has an obvious effect on the vibration velocity of the pump. Compared to the volute with rectangle tongue, the rounded tongue can decrease the vibration velocity, and larger corner radius can also suppress the vibration.