Numerical simulation of pressure fluctuation in self-priming vortex pump
Wang Yang1, Peng Shuai1, Liu Ruihua2, Liu Yang1
1.National Research Center of Pumps, Jiangsu University, Zhenjiang, Jiangsu 212013, China; 2.Jiangsu Electric Power Construction No.3 Engineering Company, China Energy Engineering Group Co. Ltd., Zhenjiang, Jiangsu 212013, China
Abstract:To study the transient flow characteristics in a self-priming vortex pump including the impeller, air-water separation chamber as well as the suction and discharge pipes, the transient turbulent flows inside a self-priming vortex pump are simulated under different flow rate conditions by solving Reynolds time-averaged N-S equations and RNG k-ε two-equation turbulence model using ANSYS CFX software. The performance predicted based on the steady flow model is compared with the measu-red one, and the steady flow field obtained is used to initialize the transient simulation; the pressure pulsations at a few monitoring points inside the pump are extracted. The results show that the dominated frequency in the pump inlet and outlet is in between the blade passing frequency and the rotational frequency. In the side flow channels contacted with the impeller, the dominated frequency is the blade passing frequency based on the number of blades in one side of the impeller, which exhibits an obvious peak in the radial direction. The fluid pressure fluctuation near the walls of the channels is mainly in the blade passing frequency of one side of impeller blades or its multiples. The pressure fluctuation in the gaps between the baffle and the impeller tip is more significant; but the peak fluctuation is commonly in the blade passing frequency of one side of impeller blades or its multiples except a dispersion of the fluctuation at low frequencies. In the gap, the pressure fluctuation in the blade passing frequency of one side of impeller blades is declined but the fluctuation in the blade passing frequency of the whole impeller blades is increased when a monitoring point is shifted circumferentially from the two boundary edges to the centre of the gap. The denominated frequency of pressure pulsation in the impeller passages is the rotational frequency, and the peaks of the pulsation are in the rotational frequency or its multiples, furthermore, the peaks themselves decrease with the increasing multiple.
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