The flow field in a three-stage centrifugal pump was simulated by using CFX software based on the standard k-ε turbulence model, the predicted performance curves were compared with the measurements, and good agreement was showed. After a further analysis on the flow details, however, a larger hydraulic loss has occurred in the gap between the impeller and the bowl diffuser as well as in the diffuser itself. In order to reduce the hydraulic loss and improve the matching characteristic of the diffuser to the impeller, four diffusers with different inlet structures are designed. The steady flow in the three-stage pumps with these diffusers is simulated at the design point, and the pump performance, flow pattern and the pressure distribution over the diffuser vane pressure side are analysed. The results show that the diffuser with untwisted inlet and in parallel with the impeller outlet has the best hydraulic performance. The diffuser with twisted inlet results in an increased impeller head, but the hydraulic loss in the gap between the impeller and the diffuser rises, and the pressure at the inlet of diffuser becomes instable. The diffuser with inlet edge in parallel with the impeller outlet can reduce the inside loss to improve the hydraulic performance. Even though the diffuser with inlet edge in parallel with the pump shaft can compromise the interference with the impeller to increase the impeller hydraulic performance, the hydraulic loss in the gap is increased.
WANG Kai-,WANG Wen-Bo-,LIU Hou-Lin- et al. Matching characteristic between impeller and bowl diffuser in multi-stage centrifugal pump[J]. Journal of Drainage and Irrigation Machinery Engin, 2016, 34(5): 392-398.
BONAIUTI D,ZANGENEH M,AARTOJARVI R,et al.Parametric design of a water-jet pump by means of inverse design,CFD calculations and experimental analyses[J].Journal of fluids engineering,2010,132(3):1-5.
MA Wenchang, CAO Hui, SONG Shaolei. Inverse design of water jet pump and anti-cavitation analysis[J]. Journal of Jiangsu University of Science and Technology(natural science edition), 2013, 27(3): 219-223.(in Chinese)
KIM Sung,CHOI Young-Seok,LEE Kyoung-Yong,et al. Design optimization of mixed-flow pump in a fixed meridional shape[J].International journal of fluid machinery and systems,2011,4(1):14-24.
KIM Jin-Hyuk,KIM Kwang-Yong. Optimization of vane diffuser in a mix-flow pump for high efficiency design[J].International journal of fluid machinery and systems,2011,4(1):172-178.
FERRO L M C, GATO L M C, FALCAO A F O. Design and experimental validation of the inlet guide vane system of a mini hydraulic bulb-turbine[J]. Renewable energy,2010,35:1920-1928.
WANG Pengfei, RUAN Xiaodong, ZOU Jun, et al. Medial axis transform method for shape design of hub and shroud contours of impellers[J]. Journal of fluids engineering, 2011, 133: 034502.
KONG Fanyu, WANG Ting, ZHANG Hongli. Rotor dynamic analysis of multistage pump based on numerical simulation of flow field[J]. Journal of Jiangsu University(natural science edition), 2011, 32(5): 516-521.(in Chinese)
WANG Jiaqiong, KONG Fanyu. Hydraulic performance optimization study on impeller and diffuser of multi-stage centrifugal pump[J]. Journal of Huazhong University of Science and Technology(natural science edition), 2013, 41(3): 92-96.(in Chinese)