STUDY OF SYSTEM PARAMETERS OF SAVONIUS HYDROKINETIC TURBINE

Abstract

Extraction of hydrokinetic energy from in stream flow can be an effective, sustainable and environmental friendly replacement of the conventional energy resources. Savonius hydrokinetic turbine is a vertical axis turbine which has a poor efficiency and its operating range under various loading conditions is very less. The coefficient of performance value reported under different investigations on Savonius hydrokinetic turbine for increasing its efficiency is highly varied in respect of tip speed ratios (TSR). In order to enhance the efficiency of the turbine and to get less variations in coefficient of power output for smooth operation under higher range of tip speed ratios, the work under this dissertation aims to model a modified design of Savonius turbine with twisted blades and analyze its performance under different operating conditions. For CFD analysis commercial unsteady Reynolds-Averaged Navier-Stokes (URANS) solver in conjunction with SST k- ω turbulence model has been used. Due to complex geometry 3D transient simulations are done to find out the average torque. Coefficient of torque and coefficient of power are analyzed and discussed. CFD results are validated with the experimental results. In order to conduct the experiments, a model of modified Savonius hydro kinetic turbine has been developed and tested in Hydraulic Measurement Laboratory at AHEC, IIT Roorkee. Based on the results obtained it is observed that not much variation is found in power coefficient up to tip speed ratio 1.4 which indicates the increment of operating range and beyond TSR value of 1.4, coefficient of power decreases sharply. The maximum power coefficient obtained as 0.30 corresponding to a TSR value 1.4 for water velocity of 2 m/sec. This study may be useful for further study the performance of Savonius hydrokinetic turbine under different operating and system parameters