Study Of Horizontal Axis Wind Turbine Blade Icing

Wind power has characteristics of clean,non-pollution,renewable,flexible installation,etc.It has been widely developed around the world.In order to make full use of wind power,many horizontal axis wind turbines are installed in mountains,borderland and coastal wet regions.These regions often appear low ambient temperature,high air humidity,freezing rain,snow,and other bad weather.At this situation,wind turbine blade will cover with ice.Icing can cause blade aerodynamic performance deterioration and rotor output power reduction.Icing can also damages systems stability and causes operational accidents.In order to reduce icing negative effect,it is necessary to study wind turbine blade icing problem.In order to study wind turbine blade icing,the water droplet collection efficiency on blade surface should be firstly obtained.It represents water droplet distribution on blade surface,and it is the key basic data to study blade icing.Therefore,in this paper,calculation model of water droplet collection efficiency is developed.Effect of different parameters on water droplet collection efficiency of airfoil is studied.Distribution of water droplet collection efficiency on static and rotating blade is analyzed.Icing model is established based on water droplet collection efficiency.Effect of different parameters on icing of wind turbine airfoil is analyzed.Icing distribution on rotating wind turbine blade is studied.Finally,icing effect on wind turbine load is studied by using engineering calculation method.The main research contents are as follows:1.Calculation model of water droplet collection efficiency on wind turbine airfoil is established.Effect of angle of attack,inflow wind speed,and medium volume diameter on water droplet collection efficiency is studied.As angle of attack increases,maximum water droplet collection coefficient on airfoil surface decreases.Under large stall angle of attack,water droplets except impinge at airfoil leading edge,airfoil trailing edge surface has little water droplets impingement.Impingement range and maximum water droplet collection efficiency increase with increase of stall angle of attack.Water droplet collection efficiency increases with increase of inflow wind speed and medium volume diameter.2.Influence of tip 3D effect on water droplet collection efficiency of static blade is analyzed.Due to 3D effect,water droplet collection efficiency dramatically decreases at blade tip region of static blade.Rotating effect of wind turbine blade is analyzed.Water droplet collection efficiency increases along radial direction of rotating blade.Rotating stall delay effect on water droplet collection efficiency is studied under large inflow wind speed condition.Rotating stall delay effect has little influence on water droplet collection efficiency of blade surface.3.Icing model on wind turbine airfoil is established.Effect of angle of attack,inflow wind speed,medium volume diameter and liquid water content on wind turbine airfoil icing is studied.Meanwhile,icing on rotating wind turbine blade is studied.As airfoil angle of attack increases,icing region moves towards airfoil pressure surface,maximum ice thickness increases.Ice amount increases with increase of inflow wind speed,medium volume diameter and liquid water content.Under rotating condition,ice thickness increases along blade radial direction.4.Aerodynamic load calculation model is used to study icing load of stall regulated wind turbine.Research load parameters include wind rotor power,wind rotor thrust,wind rotor shaft shear force,blade root edgewise moment,blade root flapwise moment,tower base side to side moment,and tower base fore after moment.Under normal turbulence wind condition,icing can decrease wind rotor power.One blade icing can induce imbalance shear force on wind rotor shaft.5.Icing load of variable speed variable pitch wind turbine is studied.Research load parameters include wind rotor power,wind rotor thrust,blade root edgewise moment,blade root flapwise moment,blade root pitching moment,tower base side to side moment,tower base fore after moment,and tower base torsional moment.Under normal turbulence wind condition,when inflow wind speed is less than rated inflow wind speed,icing can decrease wind rotor power.When inflow wind speed is greater than rated inflow wind speed,icing can cause increase of wind rotor thrust,blade root flapwise moment,blade root pitching moment,tower base side to side moment,tower base fore after moment,and tower base torsional moment.