Numerical Simulation Of Aerodynamics Of Wind Turbine With Immersed Boundary Method

The aerodynamic performance of wind turbine largely determines the safety and efficiency.Development of efficient and accurate numerical simulation for the aerodynamics is challenging owing to its complexity.In this study,the aerodynamic dynamics of wind turbines with different airfoil,single-stage and two-stage wind turbine were studied by immersion boundary method.The main work and valuable conclusions of this paper are as follows:(1)The immersed boundary method can accurately simulate the lift of airfoil,but for the drag,it has strict first-order accuracy for the grid size.A simple and effective error estimation modification method is proposed,that is,a linear curve is constructed by selecting the simulation results under any two kinds of grids,and the intersection point of the curve and the vertical axis is the error under ideal conditions.(2)Under the simulation condition Re=2×10~4,the efficiency of three-blade wind turbine is significantly higher than that of two-blade wind turbine and is 2.2 times of that of two-blade wind turbine.The tower will affect the velocity and pressure distribution,but the influence on key parameters such as moment is small.The power coefficient of the wind turbine reaches the maximum value of 0.43 when the optimal tip speed ratio is 5.At the tip of the blade,the airflow velocity is the highest,and some vortices fall off from the wing tip and spin into the wake.A convenient and efficient optimization algorithm,which includes automatic selection of airfoil type,twist angle and size,grid discretization and numerical simulation,is proposed.(3)When the interval between the two wind turbines is 1.5D,3D and 4D(D is the diameter of the wind wheel),the speed at the center line behind the first wind turbine reaches a stable and recovers to 50%,60% and 75% of the incoming flow speed respectively.And the second wind turbine can be installed outside 3D to 5D behind the first wind turbine.