Numerical analysis of vertical axis wind turbine

A model for the aerodynamic evaluation of a vertical-axis wind turbine (VAWT) to improve its torque characteristics has been analysed. VAWT is more promising especially in areas with frequent light winds. This paper represent a numerical analysis of the aerodynamics performance on the straight blade fixed pitch VAWT (3 blades) based on the NACA 0018 airfoil. A solid modelling software ANSYS FLUENT which is linked to a finite volume Computational Fluid Dynamics (CFD) is used for the calculation of rotor performance. Gambit software is used to create 2D model of the turbine and the mesh which is generated in Fluent for numerical iterate solution. The Unsteady Reynolds averaged Navier-Stokes equation is used for the investigation of general effects on the performance of several geometry characteristics of two-dimensional airfoils. The RNG k-epsilon model is adopted for the turbulence closure. For proposed rotor analysis, flow field characteristics are investigated at different values of tip speed ratio and also the dynamic quantities such as rotor torque co-efficient and power co-efficient for a constant free stream velocity for 9 m/s which correspond to Reynolds numbers based on chord length of 2.6×105. The VAWT has an inherent unsteady aerodynamic behaviour due to the variation of angle of attack with the angle of rotation, perceived velocity and consequentially Reynolds number. This approach is necessary for having a numerical analysis at low computational cost and time.