3D Potential Flow Model of Tower Interference for Upwind Wind Turbine. (3rd June 2014) - Zhang, Pinting
Abstract : With the upscaling of wind turbine, models of wind shear and tower shadow play an increasingly significant role in the aerodynamic calculation. Although Computational Fluid Dynamic (CFD) method gives more accurate results than Blade Element Momentum (BEM) method, BEM remains the primary method for calculating aerodynamics and aeroelasticity of wind rotor. Firstly, this paper reviews several 2D and 3D potential tower interference models for BEM method. 2D model is much easier to compute but cannot simulate the "end effect" of tower. Previous 3D model can provide more accurate result than 2D model, but it yields an incorrect approximation of nonzero vertical velocity on ground. Then, in this paper, a new 3D model is proposed to address this problem and is compared to previous models. A CFD method is used to verify the level of fidelity of the models. The normal velocity on tower surface and the attachment point of the variable models are compared, while the induced velocity on ground and the upstream velocity of the tower in x -direction at several distances are analyzed. Finally, NREL-5MW RWT was used as an example to show how the model is used in BEM method.