Numerical and experimental study of using axial pump as turbine in Pico hydropower plants

Low head Pico hydro resources have considerable potentials in many regions of the world and with increasing demand of energy, use of such capacities is quite necessary. Pico hydro plants are usually isolated and installed in remote areas. One of the main problems of utilizing these potentials especially in the developing countries is that routine turbines are insufficient or proper turbines are expensive. A suitable alternative for solving this problem is use of axial pumps in the reverse mode instead of the routine turbines. In this mode, the flow and rotation direction of the pump are reversed, and consequently hydraulic behavior of the pump is changed. In this study, an industrial axial pump has been simulated in the reverse mode by computational fluid dynamics. To do so, continuity and Reynolds Averaged Navier–Stokes equations coupled with Spalart-Allmaras turbulence model were solved using NUMECA software, and characteristic curves were obtained. To validate numerical results, a test setup for measuring the head, flow rate and power was built and the pump was tested in the reverse mode. It is shown that there is a good coincidence between the numerical and experimental results. Also, the axial pump can properly work as a turbine in the low head Pico hydro plants.