블레이드 팁 영역의 전연 마모 발달이 풍력터빈 연간발전량에 미치는 영향

Abstract

With the Renewable Energy 3020 policy and the 2050 Carbon Neutral(Net-Zero) promotion strategy, installed capacity of wind turbines, which is currently only 1.7GW, will be expanded to 17.7GW by 2034. Accordingly, the construction of a large-scale wind farm is expected, and it is economical to use a wind turbine with higher rated power as the facility capacity of the wind farm increases on a large scale. The rated power of the wind turbine is increased, rotor diameter and tip speed are increased, and it is predicted that damage to the blade leading edge due to rain droplets will occur more frequently due to the increase in tip speed. The blade tip region is composed of an airfoil with high aerodynamic performance, and leading edge erosion occurs in the tip region airfoil, the aerodynamic performance decrease, than AEP(Annual Energy Production) of the wind turbine may be significantly reduced. Many researchers have conducted studies on the reduction of wind turbine AEP due to leading edge erosion. Wind tunnel tests are most appropriate to analyze the reduction in airfoil aerodynamic performance and the AEP of wind turbine due to leading edge erosion, but numerical simulation using CFD(Computational Fluid Dynamics) are mainly used because large-scale test equipment and considerable cost are required. Existing studies have analyzed by applying leading edge erosion, contamination, icing to 2D airfoil, but airfoil generate 3D recirculation regions that develop very complexly in the trailing edge, 3D airfoil can simulate physical phenomenon more accurately. In this study, CFD simulation was conducted using 3D airfoil to propose changes in tip airfoil’s aerodynamic performance and flow characteristics due to leading edge erosion growth of blade and the reduction rate of AEP. The erosion class was defined by the erosion shape obtained from actual wind farm, and this was applied to the NACA64-618 airfoil to obtain aerodynamic performance. The AEP of wind turbine was predicted by applying the aerodynamic performance of the eroded airfoil to the BEMT(Blade Element Momentum Theory) based software. In order to verify the reliability of the CFD simulation, the results of Timmer’s wind tunnel test were compared at 6 million Reynolds number. In order to select a turbulence model suitable for the airfoil, RANS(Reynolds Averaged Navier-Stokes)-based turbulence models and DES(Detached Eddy Simulation) model were compared, and SST(Shear Stress Transport) K-ω γ-Reθ model used in terms of prediction accuracy and computational efficiency of the turbulence model. When the erosion class defined in this study was applied, the lift coefficient decreased by up to 40%, and the drag coefficient increased by up to 115% compared to the clean airfoil. As the depth and range of erosion area increased, the rate of reduction in aerodynamic performance was increased. When the AEP of wind turbine was predicted using BEMT under the condition of average annual wind speed 6m/s, it decreased by at least 0.35% and up to 2.3% compared to the clean blade.