Optimization Design And Aerodynamic Performance Analysis Of Large Horizontal Axis Wind Turbine

With the continuous development of the wind power industry,wind turbines are increasing in size.However,wind turbines often face various complex environmental factors such as turbulence,wind speed,and wind direction,which significantly impact the safety and performance of the turbine blades.As the core component of wind turbines,the design and performance analysis of turbine blades are essential for improving the performance and stability of wind turbines.Currently,most research focuses on steady-state flow conditions,with limited studies analyzing the aerodynamic characteristics of large-scale horizontal axis wind turbines under unsteady flow conditions.Therefore,this study designs a 1.5 MW horizontal axis wind turbine based on the Blade Element Momentum(BEM)theory and conducts aerodynamic analysis using both Computational Fluid Dynamics(CFD)and BEM theory under different flow conditions.The main contents are as follows:(1)Design and establishment of a three-dimensional model of the wind turbine to validate its accuracy.Based on the BEM theory and Wilson method,MATLAB’s nonlinear constrained optimization toolbox is used to optimize the chord length and twist angle of the turbine blades,with the objective of maximizing the wind energy utilization coefficient.The design considers the hub and tip losses of the wind turbine.The chord length and twist angle data of each airfoil along the blade span are obtained through calculations,and a three-dimensional model of a 1.5MW wind turbine is established using modeling software.(2)Aerodynamic performance analysis of the wind turbine using different calculation methods.The computational domain is divided,and an unstructured grid is employed.The SST k-ω turbulence model is used to perform numerical simulations on a two-dimensional airfoil under rated conditions to verify the accuracy of turbulence simulations.The analysis includes the one-way fluid-structure coupling of flexible blades and obtains velocity contour maps and flow streamline diagrams at different positions.The results show that there is a significant pressure difference between the upper and lower surfaces of the middle and tip sections of the blades,which is the main region for generating kinetic energy.The blades exhibit strong stiffness,with minimal deformation and no resonance occurring during operation,indicating that the design meets performance and reliability requirements.The QBlade software is used to calculate the blade loads,considering two correction methods for the root and tip of the BEM.The results are compared with CFD calculations,showing that the lift coefficient is smaller at the root and larger at the tip,and the normal force and tangential force exhibit the same trend.The Shen-corrected BEM provides more accurate predictions of the normal force compared to the Prandtl-corrected BEM.(3)Analysis of unsteady aerodynamic characteristics of the wind turbine under different flow conditions.Under the influence of centrifugal force and Coriolis force,flow separation occurs on the suction surface of the blades,and root and tip vortices are observed.As the wind speed increases,the stall region gradually enlarges.Numerical simulations using the Improved Delayed Detached Eddy Simulation(IDDES)and Reynolds-Averaged Navier-Stokes(RANS)methods for the wake of the wind turbine reveal that IDDES captures more precise vortex structures,while RANS exhibits lower accuracy in describing turbulent flow.The influence of sinusoidal oscillating flow on the performance of the wind turbine is studied using User-Defined Functions(UDFs),and the results indicate that under unsteady flow conditions,the tip region,especially the leading edge on the suction surface,is highly sensitive to the incoming flow.