Experimental and numerical investigation on application of half vane diffusers for centrifugal pump

Vaned diffusers are widely used in centrifugal pumps, but little research has been published regarding action mechanism and the influence of diffuser vane height on dynamics performance of centrifugal pumps. Experimentally and numerically, the present investigation was focused on the dynamics performances of a low specific speed centrifugal pump equipped with vane diffusers with different vane heights. The pump performance was appraised when the diffuser vane height (h/b) was 0 (vaneless), 0.5, 0.6, 0.8 and 1 (vaned) times the diffuser width respectively. The pressure fields were numerically simulated in order to study the influence of half vane diffusers on inner flow field. The experimental results of operating performance showed that the efficiency was significantly improved for 2.5% at design flow point and the head was significantly improved for nearly 3 m at over flow point. The best efficiency point shifted towards higher flow rate with h/b reducing, and the high efficiency area was broadened by using half vane diffusers. Besides, half vane diffusers could reduce the intensity of pressure fluctuations at the leading edge of the stator vanes, and reduce the influence of rotor-stator interaction in tongue region. The numerical results showed that half vane diffusers could enhance flow uniformity in pumps, symmetry of pressure distributions on the impeller outlet and preferable regularity of radial force distributions. Therefore, it is very useful and feasible to apply half vane diffusers in centrifugal pumps.