Effects of Blade Outlet Width on Flow Field and Characteristic of Centrifugal Pumps

Abstract

The present deficiency about numerical simulation research on blade outlet width of centrifugal pumps is pointed out. In the case of different outlet widths, the flow field in six centrifugal pumps whose specific speed vary from 45 to 260 are simulated by using commercial code FLUENT and the characteristics are predicted. The standard k-ε turbulence model and SIMPLEC algorithm are chosen in FLUENT. The simulation is steady and moving reference frame is used to consider rotor-stator interaction. The research results show that the change of impeller outlet width has obvious impacts on characteristics at design point, flow field and the shape of performance curves. At nominal condition, the change of outlet width has more important effects on moderate specific speed centrifugal pumps. The flow field analysis indicates that blade outlet width change has an important effect on the location and area of low pressure region behind the blade inlet, jet-wake structure in impellers, the secondary flow in volute cross section and the back flow in impellers. The head-flow curve becomes more flat with the increase of outlet width. For moderate and low specific speed centrifugal pumps, the high efficiency area of efficiency-flow curve get bigger with the increase of outlet width and the area will be constant within certain outlet width change scope for high specific speed centrifugal pump. The research results agree well with experiment results.