Effects of diffuser vane on mixedflow pumps performance
BING Hao1, CAO Shu-Liang1, TAN Lei2, LU Li3
(1.State Key Laboratory of Hydroscience and Engineering, Tsinghua University, Beijing 100084, China; 2.State Key Laboratory of Tribology, Tsinghua University, Beijing 100084, China; 3.Hydraulic Machinery Department, China Institute of Water Resources and Hydropower Research, Beijing 100038, China)
A series of vaneddiffusers, which are with various vane inlet angles, vane angle distributions along streamline, leading and trailing edge positions, were designed for a mixedflow pump impeller by using the pointbypoint integration method that was applied to generate the threedimensional camber of vane on the streamlines determined by employing an iterative calculation between two kinds of relative stream surfaces. The vane thickening and leading and trailing edges smoothing were conducted on a plane of conformal mapping.3D turbulent flow fields inside the mixedflow pump with the same impeller but different diffusers were simulated by solving the Reynolds timeaveraged N-S equations and the standard k-ε turbulence equations based on SIMPLE algorithm, and the pump hydraulic efficiencies were predicted, consequently, the correlations of both the vane wrap angle and hydraulic efficiency to different design parameters were obtained. In addition, effects of various design parameters on the mixedflow pump performance were analyzed by means of relative velocity, static pressure and total pressure distributions in the inlet and outlet to the diffusers.The results showed that the diffuser vane inlet angle has the strongest influence on the performance and a reasonably selected inlet angle can reduce the shock loss. The vane angle distributions along streamlines should be selected by considering the control of wrap angle to reduce the hydraulic friction loss in diffuser. The leading edge and trailing edge positions should be selected with the consideration of static pressure recovery ability and hydraulic friction loss across diffuser.
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