Effect of tip clearance on unsteady flow in axial-flow pump
Li Yaojun1, Shen Jinfeng1, Hong Yiping1, Tang Xuelin1, Zhang Zhimin2
1.College of Water Resources & Civil Engineering, China Agricultural University, Beijing 100083, China; 2.China Institute of Water Resources and Hydropower Research, Beijing 100044, China
Abstract：In order to study the influence of the tip clearance on the unsteady flow and performance of the axial-flow pump, adopting the Spalart-Allmaras model based detached eddy simulation(DES)method and sliding mesh technique, numerical simulations of internal turbine flow of the axial-flow pump under designed conditions were carried out. The internal unsteady flow and its pressure pulsations of four different tip clearance sizes were simulated and analyzed. With the designed tip clearance, the predicted pump head and efficiency matched well with the measured data, and the maximum relative errors were less than 2.0% and 3.0%, respectively. The numerical results show that the pump performance, especially the head and efficiency tend to decrease as tip clearance becomes bigger; the intensity and range of the tip clearance vortex increase as the tip gap grows. When the gap reaches 3.3‰D2, the tip clearance vortex expands to the trailing edge of the neighboring blade. The results also show that the blade passing frequency dominated the pressure fluctuations in the impeller. The increase of the blade tip gap led to a reduction of the maximum pressure fluctuation amplitude on the front part of the impeller casing, but an increase on the middle part of the impeller casing. Pressure fluctuations in the impeller-vane gap region are dominated by the blade passing frequency(fn), while the maximum pressure fluctuation amplitude was observed to decrease as the tip clearance size increases.
黎耀军, 沈金峰, 洪益平, 唐学林, 张志民. 轮缘间隙对轴流泵内部非定常流场的影响[J]. 排灌机械工程学报, 2013, 31(8): 667-673.
Li Yaojun, Shen Jinfeng, Hong Yiping, Tang Xuelin, Zhang Zhimin. Effect of tip clearance on unsteady flow in axial-flow pump. Journal of Drainage and Irrigation Machinery Engin, 2013, 31(8): 667-673.
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