Flow pattern and hydraulic performance of tubular pump

In order to establish a relationship between flow pattern and hydraulic performance of a tubular pump, the flow pattern and hydraulic performance at a low flow rate, best efficiency point and a high flow rate were investigated by means of flow simulation, performance test and PIV measurement in a tubular pump. The steady flow field in the pump was obtained through solving the time-averaged N-S equations in the multiple reference frames (MRF) with the help of the SIMPLEC algorithm and the RNG k-ε turbulence model. The flow patterns in the pump were analyzed at different operating points. There was a large recirculation zone before the blades inlet when the pump operated at the low flow rate. The flow patterns were fine and there was no any reverse flow regions in the pump when it worked at the BEP (Best Efficiency Point) and the high flow rate. The results indicated the hydraulic loss in the suction pipe is similar to that in a normal pipe, but the hydraulic loss in the discharge pipe depended on operating points. A minimum hydraulic loss in the discharge appeared at the BEP. The estimated performance was in agreement with the test data, both the predicted flow patterns and the PIV measurements showed that there was remarked reverse flow region in front of blades near the tip and there existed a large separated flow zone near the hub downstream of blades at the low flow rate. Thus, attention should be paid on the flow pattern in impeller and guide vanes at a low flow rate in the optimal design of such a tubular pump.