Abstract
Leading Edge Roughness (LER) has become a critical challenge for wind turbine operators, often reducing the energy production of their turbines. LER has not yet been systematically categorized, and the transfer function between height/extent of roughness and the aerodynamic performance has not been established. A common method for emulating LER is to use zigzag tape or distributed sand grain roughness in a wind tunnel. This paper contains 2D and 3D CFD simulations and wind tunnel tests with zigzag tape on a NACA 633-418 airfoil, to evaluate the changes in aerodynamic characteristics. Because 3D CFD requires a vast amount of computing power, it is investigated if 2D simulation gives a sufficient level of accuracy.
Highlights
It is known that the flow behavior of a fluid is influenced by the shape and the conditions of the surfaces nearby where the fluid passes [1]
The Leading Edge Roughness (LER) often causes a 1-7% loss in annual energy production (AEP), but it can cause as high as 20% for some airfoil families in severe cases [5,6,7]
The objective of this paper is to investigate the possibility of simulating the flow on the NACA 633-418 with protuberances modeled in the grid in 2D and predict the aerodynamic characteristics
Summary
It is known that the flow behavior of a fluid is influenced by the shape and the conditions of the surfaces nearby where the fluid passes [1]. A rough surface is known to have a negative impact on the boundary layer properties resulting in a higher drag, and for airfoils a decrease in lift. Wear and tear of the wind turbine blades over time can result in erosion that gives the surface a certain roughness height. These different disturbances are generally described as Leading Edge Roughness (LER). The LER often causes a 1-7% loss in annual energy production (AEP), but it can cause as high as 20% (estimated by PROPID based on Wind Tunnel Tests, see [4]) for some airfoil families in severe cases [5,6,7]. The loss in AEP dealt with in this paper is less severe
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