Numerical simulation of the performance of tandem axial flow pump

To shed light on the flow mechanisms associated with performance characteristics of a tandem pump, two axial flow impellers, which have been tested experimentally, are used to form a tandem axial flow pump model. Pro-Engineer software is used to create the 3D solid model of the pump. The internal flows and the performances of the pump are simulated numerically. The computations are performed by using NUMECA commercial software. For various working conditions, the velocity distributions in both the front and rear impellers are obtained. Based on the computational fluid dynamics (CFD) results, the performances, including the head, efficiency and shaft power of the tandem pump are predicted under different flow rates. The numerical results are compared with the experimental performances. Compared with that in the front impeller of the pump, difference between the velocities on the pressure and suction surfaces of the rear impeller is large. The tandem axial flow pump has unique performances which are different from a conventional axial flow pump obviously. The operating range with higher efficiency becomes wider and the optimum operating condition is attained at higher flow rate. The shaft power does not decrease with the increasing of the pump flow rate. To address the interactions between the front and rear impellers, the performance of the pump also predicted in different blade angles of the rear impeller. The results show the changes of the blade angle can sufficiently affect the pump performances.