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| Linear control design and internal flow analysis of diffuser trailing edge based on CFD |
| GONG Xuran1,CAO Puyu1*,WANG Yang1,ZHU Rui2,WANG Yefu1 |
| 1. National Research Center of Pums, Jiangsu University, Zhenjiang, Jiangsu 212013, China; 2. Energy and Power Engineering Institute, Xi′an Jiaotong University, Xi′an, Shaanxi 710000, China |
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Abstract In order to improve the hydraulic performance of multistage submersible pump, the method of combining test verification and numerical simulation was adopted for Q80-20 multistage submersible pump. The linear equation was used to express the variation of the wrap angle of the diffu-ser and explore the influence of the change of equation slope on the separation flow in the corner of diffuser. CFX17.1 was used to simulate the whole flow field of the two-stage model, and the results show that the hydraulic performance of diffuser is better when the slope of linear equation is negative than positive. On the basis of negative slope, two schemes are adopted for optimization. When the linear equation intercept is kept constant and the slope is gradually reduced, the results show that the transverse secondary flow in the center of the hub is weakened, the spanwise secondary flow from the hub to the shroud is enhanced, the accumulation of low-energy fluid in the corner region is inhibited. The performance of diffuser increases unidirectionally with the decrease of slope. Shroud wrap angle remains unchanged, and the gradually decreasing slope also enhances the spreading secondary flow from the central hub to the shroud. However, the energy loss increases due to the intensified transverse scour at the inlet, which results in first increase and then decrease of the hydraulic performance of the diffuser, and there is an optimal slope. The results provide the research foundation and scientific support for the subsequent research on the influence of diffuser stacking on the hydraulic performance of multistage submersible pumps.
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Received: 05 February 2021
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