Large Eddy Simulation of flow around a Horizontal-axis wind Turbine at Different Rotational Speed

The present study focuses on the flow around a horizontal axis wind turbine. Large Eddy Simulation has been employed in order to study the flow at different rotational speeds. Anisotropic residual stress tensor is driven by The Smagorinsky model. Three simulations were performed at different tip speed ratio of 3, 6 and 10. The acquired results are in good agreement with presented experimental data in literatures. It is also revealed that development of the wake is decreased when downstream velocity is increased along the horizontal line at different downstream distance of wind turbine. In addition, velocity defect behind the wind turbine is increased when tip speed ratio increases but the recovery of wake is happened faster. At rotational speed equals 6, minimum velocity is 54% of the initial velocity and maximum efficiency is 67% at the lateral section of wind tunnel where the tip of blade is located, while they are 26% and 68% respectively when rotational speed is 10. Turbulence intensity is increased by increasing Tip Speed Ratio while separated vortices from the blade are disappeared later. The effect of separated vortices from the blades of wind turbine are not seen when rotational speed is 3, while they are revealed at rotational speed of 6 and 10. As a result, it can be concluded that the effect of separated vortices are augmented when rotational speed is increased.