Turbine-concentrator design optimization performance tests for small scale wind and hydrokinetic energy turbines

The importance of wind and hydrokinetic energies which are kinds of renewable energy is increasing day by day. In this context, many studies are carried out to improve turbine performance. In this study, a system optimization is made in order to maximize the free stream velocity at the small capacity turbine entry zone by considering turbine-concentrator combination. It is aimed to increase the turbine performance and to generate energy in lower speeds for wind and hydrokinetic turbines. In the optimization studies, the geometric parameters of the concentrator which define the system are obtained by using 2D CFD analysis and RSM being used together. In 2D analysis, turbine inside the concentrator is modelled with disc approach. Free stream velocity at the disc zone is increased approximately by 1.2 times. 3D CFD analysis are carried out with the usage of optimum geometric parameters. Bare turbine efficiency with the concentrator is increased to 1.11 from 0.43 in the condition when rotor diameter is 0.9 m and Reynolds number is 115000 value. On the other hand, with the usage of concentrator with flap, it is proved that the minimum operation velocity of the turbine is decreased by % 19. Thus, it is proved that the power value is 2.58 times increased by the usage of concentrator and due to the decrease of minimum operation velocity of the turbine, energy is seen to be generated in the zones where there is insufficient wind speed.