Numerical Study of a Pico Hydro Turbine

Abstract

Pico hydro turbines (PHT) are suitable for low head applications in power plants since their efficiency is more stable than other turbine types. In some situations, computational fluid dynamics (CFD) has been also utilized as well as experimental studies for the performance prediction of water turbines at a pico scale. Also, CFD methods are getting much closer to real conditions in terms of steady-state with moving references, and transient domains with rotor movements. For this purpose, electricity production related to the flow in a PHT was investigated numerically. This study presents the method to predict the maximum conditions of a pico scale two-dimensional turbine by comparing the torque (τ) and angular velocity (ω) on the runner based on turbine output power. Besides, the effect of the torque, angular velocity, tip speed ratio (TSR), and turbine body profile was investigated comprehensively. In this regard, the CFD method with moving reference frame (MRF) and six degrees of freedom (6-DOF) were performed in order to validate and compare the numerical model with the experimental data. Compared with the experimental study, the numerical results for the performance of the pico hydro turbine were reasonable. It is also concluded that there is a tip speed ratio of 2.36 with the MRF method and 0.48 with the 6-DOF method between water tangential velocity and runner velocity for the turbine model.