High-fidelity computational assessment of the performance of unsyncharonized vertical axis wind turbines

The Horizontal Axis Wind Turbines (HAWTs) are ruling the commercial wind turbine industry because of its higher efficiencies compared to the Vertical Axis Wind Turbines (VAWTs). However, the simple construction, hence low production cost, inherent design, and cheaper operation of the VAWT make it suitable for the small scale wind energy systems and hence can be installed in the urban area. Computational modeling of the VAWT for the TSR which corresponds to the maximum power output is studied. To compute the flow parameters numerically two turbulence modeling approaches have been used, namely Reynolds Averaged Navier-Stokes (RANS) using the Spalart-Allmaras turbulence model, which is most popularly used for external aerodynamic modeling and the Large Eddy Simulation (LES) using Wall-Adapting Local-Eddy Viscosity (WALE) model. Despite of having a high computational cost, the LES turbulence model is useful to accurately capture the turbulent flow and the effects of small and large scale sized eddies which are caused by the wind forces. The computational studies of the combination of the lift and drag type of iv VAWTs are done to analyze the combined advantages of the both rotors. Also, the Darrieus rotors are synchronized using the pair of the spur gears at different interferences to check the optimum overlap interference for maximum power output. These studies are done to check the improvement in the performance of the VAWTs, and optimization in the spacing of the turbine placed side by side to each other, etc.