Computational and Experimental analysis of a Counter-Rotating Wind Turbine system

300-306Wind power is a sustainable and clean source of energy. Single rotor wind turbines (SRWT) of horizontal in nature are the conventional wind turbines, which are used to extract the power from wind. In the past two decades, research have been carried out on Counter Rotating Wind Turbine (CRWT) system and reported that the power extracted is relatively more for a given swept area than that of a SRWT. In the present study, a CRWT, having primary (upwind) and secondary (downwind) rotors with different diameters, which has been reported in a literature is considered and analyzed for its turbine characteristics (power, torque) using commercial software Fluent 6.2 and wind tunnel testing. The flow around the SRWT and CRWT was simulated by using finite volume method coupled with Moving Reference Frame (MRF) technique to solve the governing equations. In this present study the Standard k-ω shear stress transport turbulence model was considered. For pressure-velocity coupling of the flow second-order upwind discretization scheme (SIMPLEC) was adopted. The results on the power output from SRWT and CRWT using Computational Fluid Dynamics (CFD) have been compared with the literature values. A parametric study on axial distance between two rotors have also been investigated by CFD and it is observed that for 0.65d (d is diameter of primary rotor) the power increase is about 10% for a wind velocity of 10 m/s. Further, a scaled model of CRWT is fabricated using Rapid Prototyping-FDM technique for optimum axial distance of 0.65d with the accuracy of 0.1mm and wind tunnel testing was done with the prony brake-strain gauge assembly for various velocities and it is predicted that there is a power increase for CRWT comparing SRWT