Simulation study of Savonius tandem blade wind turbine using an adjustable deflector

Abstract

The conventional Savonius wind turbine has two inverted cylindrical blades, it can indeed receive fluid impulses from all horizontal directions and produce a greater drag force than other wind turbines. The weakness of Savonius is the resistance in one blade side. Efforts to improve that has been done is to add a blade that serves to increase the local velocity of fluid flow to resist the resistance which is termed Savonius tandem blade (STB). This research was conducted to further reduce the resistance value of one side STB with the addition of an adjustable deflector. The purpose of this study is to obtain information on changes in the torque of the STB wind turbine on variations in the deflector angle and stream velocity. The research method used is numerical simulation using CFD software. A two-dimensional view of the rotor model using deflector was considered. The deflector angle varies start from 15 degrees with an increase also every 15 degrees until the torque decreased. The CFD simulation show there is a significant increase in torque with the addition of a deflector. Maximum torque is not achieved at one deflector angle value but is also influenced by stream velocity. At higher stream velocity there is a tendency to reach the maximum torque required larger deflector angle. Then at a certain point, the torque will decrease when the deflector angle is enlarged.