Abstract
This paper numerically investigates the effects of airfoil leading edge radius on the aerodynamic characteristics of H-rotor Darrieus vertical axis wind turbine (VAWT). 10 modified airfoils are generated by changing the leading edge radius of the base NACA 0015 airfoil from 1%c to 9%c, respectively. A 2D unsteady Computational Fluid Dynamics (CFD) model is established and validated with the previously published experimental data. The power, torque, and flow field characteristics of the rotors are analyzed. The results indicate that the maximum and minimum power coefficient at the optimum tip speed ratio (TSR) are obtained for the LE-5%c and LE-1%c model, respectively. The best aerodynamic characteristics are determined by the LE-5%c model below the optimum TSR and the LE-3%c model beyond the optimum TSR. The torque characteristics and pressure distribution for the single blades with different airfoil leading edge radius show an obvious difference in the upwind region and a very small difference in the downwind region. Moreover, the airfoil leading edge radius influences the strength, region, and diffusion rate of the vortices, being the main reason for the observed differences in instantaneous torque coefficient and power coefficient. The vortices of the LE-1%c model are stronger, larger, and diffuse slower than those of the LE-2%c and LE-5%c model at the optimum TSR.
Highlights
Wind turbines commonly contain two categories according to their axis orientation, namely horizontal axis wind turbine (HAWT) and vertical axis wind turbine (VAWT) [1]
The airfoil leading edge radius is studied by calculating the aerodynamic characteristics of H-rotor Darrieus VAWTs equipped with 10 airfoils with varying leading edge radius by 2D unsteady
The computational model validation study shows that the present 2D Computational Fluid Dynamics (CFD) model is applicable to the performance prediction of H-rotor Darrieus VAWT
Summary
Wind turbines commonly contain two categories according to their axis orientation, namely horizontal axis wind turbine (HAWT) and vertical axis wind turbine (VAWT) [1]. HAWT is the dominant type in both onshore and offshore wind farms and is suitable for the large-scale wind power generation due to its high efficiency and mature technology [2,3]. VAWT is more appropriate for urban applications and small to medium scale wind power generation. There are two types of VAWT including Savonius and Darrieus wind turbine. They are drag-based and lift-based turbine, respectively. The Darrieus VAWT has higher efficiency and lower starting torque over the Savonius one [8]. As a typical type of Darrieus VAWT, H-rotor Darrieus VAWT shows a rising
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