Investigation of slot parameters on the performance of Savonius hydrokinetic turbine: a CFD study

Hydrokinetic energy sources are considered as strong alternative to provide clean, affordable and green energy to future generation. There are different types of turbines available to harness this kind of energy resource. Among all the turbines, Savonius hydrokinetic turbines are acknowledged as the most suitable rotor for generating power from flowing water streams such as rivers and canal. The objective of this research paper is to improve the performance of Savonius hydrokinetic turbine using slotted blades. Under the present study, four different slot parameters, i.e. slot shapes, slot position, slot gaps and slot shape factor, are considered. The water velocity was kept constant as 1 m/s in this study. The fluid flow distributions that occur all around the rotor have been studied and discussed. Based on the investigations, Savonius hydrokinetic turbine having divergent slot has outperformed the all other shapes of slots for the entire range of tip speed ratio considered. The highest power coefficient of 0.2942 corresponds to the tip speed ratio value of 0.9 has been achieved for divergent slot Savonius rotor at slot position of 5% having slot gap of 3 mm and slot shape factor of 0.2.