The Flow Simulation and Experimental Study of a Large Low-Head Mixed-Flow Pumping System

A large low-head mixed-flow pumping system has been carried out based on numerical analysis of a three-dimensional viscous flow. For analysis, the Reynolds-averaged Navier-Stokes equations with a Shear stress transport turbulence model were discretized by finite-volume approximations. The result has shown that the flow in the double-helix volute passage is a spiral movement combining axial and rotary flows; the static pressure distribution in the volute is symmetric; the uniformity of axial velocity distribution and velocity-weighted average swirl angle at the outlet section is relatively low. The static pressure decreases gradually from the blade inlet to the exit on the pressure side, while increasing gradually on the suction side. The axial forces decrease gradually with the decrease of lifting head, and the radial forces decrease first and then increase. The pressure fluctuation at certain sections of the pumping system was measured from the model test. It is concluded that the pressure pulsations of impeller inlet and “ ω ” back wall of inlet passage are little influenced by operating condition. The domain frequency of the impeller inlet is approximately equal to the rotation frequency, while that of double-helix volute passage is multiple relations with the rotation frequency.