A Numerical Study on Axial Pump Performance for Large Cavitation Tunnel Operation

In this paper, a numerical investigation was carried out on the performances of a designed axial flow pump for a large cavitation tunnel. From this, the flow characteristics, force, and torque performance of the axial flow pump were investigated, and the rotating speeds of the impeller satisfying the test section speed performances required in the large cavitation tunnel were estimated. The axial flow pump was modeled such that the impeller, stator, and nacelle were located in a cylindrical tunnel. The calculations were carried out for incompressible steady-state turbulent flow considering the impeller rotating. The performance of the pump was confirmed, finding that the head gain was caused by the pressure jump downstream of the pump. The performance of the stator was confirmed to be good enough to refine the tangential flow due to the impeller rotating. To investigate the operating performance of the large cavitation tunnel, the head loss of the entire tunnel without the pump was obtained from a numerical analysis. The operating points were estimated from the specific speed–head coefficient curves, and it was found that the present numerical results were in good agreement with the experiments.