Research On Plasma Flow Control Principle And Application Of Wind Turbine Airfoil

Nowadays,as a new type of energy,wind energy has attracted widespread attention because of its great development potential,and the flow control of wind turbine blades is the focus of researchers.Flow control can improve the flow state around the airfoil and thus promote the aerodynamic characteristics.As an active flow control technology,plasma flow control is one of the current research hotspots.Firstly,the plasma flow control technology can change the flow field structure by injecting energy into the boundary layer,and inhibit the flow separation of the boundary layer to a certain extent by means of flow acceleration,which can improve the aerodynamic performance of the wind turbine airfoil.In addition,during the working process of the plasma excitation,the local high temperature and high pressure area generated by the thermal effect can change the trajectory of the surrounding objects.Therefore,it can be applied to the airfoil anti-icing field to suppress icing and reduce the loss of aerodynamic performance.Using the plasma phenomenological model,the excitation is coupled with the flow NS equation in the form of energy source term,and the control effect of the excitation on the flow state of NACA0012 airfoil at different angles of attack is simulated.The basic principle of excitation suppression flow separation is analyzed.The results show that when the angle of attack increases to 20°,the lift coefficient of the airfoil increases by 147.45% and the drag decreases by 62.92% after excitation,and the separation zone is significantly reduced by injecting new energy into the boundary layer,and the flow separation is inhibited to some extent.On the basis of numerical modeling,the influence of airfoil geometry(such as different thickness,different camber and different maximum thickness position)on the flow separation control effect is explored,and the influence of plasma actuator parameters(such as excitation voltage and excitation frequency)is also explored.The results show that the effect of plasma control flow separation decreases with the increase of thickness and camber,and the maximum thickness position weakens the control effect.At the same time,the effect of plasma control flow separation increases with the increase of excitation voltage and frequency.The impact characteristics of water droplets on the airfoil surface are analyzed.Combined with the icing mathematical model,the icing numerical simulation of the twodimensional NACA0012 airfoil under typical frost and ice conditions is carried out,and the change trend of the aerodynamic characteristics of the airfoil before and after icing is compared.On this basis,the effect of plasma in airfoil anti-icing is numerically simulated by coupling plasma excitation phenomenological energy model.The results show that the surface water droplet collection coefficient decreases from 0.739 to 0.534 after plasma excitation,which decreases by 27.7%.The local high temperature and high pressure generated by the excitation make the water droplets unable to adhere to the surface,inhibit the icing on the airfoil surface,increase the lift-drag ratio,and greatly improve the aerodynamic characteristics of the airfoil.A three-dimensional wind turbine blade model is established to simulate the flow around the stationary straight blade and the flow around the rotating blade under rated and non-rated conditions.On this basis,plasma excitation is applied to non-rated conditions.The results show that before the excitation of non-rated conditions,a large separation vortex is generated near the root of the blade,and the work capacity is lost.After excitation,the pressure difference between the upper and lower surfaces increases,and the flow separation is effectively controlled,which increases the work capacity of the blade root.By studying the principle of plasma flow control technology and applying it to wind turbine airfoils and blades,the function of inhibiting flow separation and anti-icing is realized,which provides technical reference for wind turbine blade design and optimization and provides new ideas for airfoil anti-icing.