| In recent years,with the international community's emphasis on energy transformation development and prevention and control of air pollution,the global wind power industry has developed rapidly.However,wind farms in the high-humidity and low-temperature areas in the south often have problems with wind turbine blade icing in winter,the aerodynamic performance of wind turbine blades is drastically reduced,which seriously reduces the power output of wind turbines,resulting in downtime,and brings great hidden dangers to the safe and stable operation of wind farms.At present,there are not many researches on the problem of ice coating on wind turbine blades.a few studies are numerical simulation analysis,but the simulation analysis and the actual operation of the wind farm are quite different.Therefore,through the fan blade ice coating test combined with the numerical simulation method,the ice coating growth process of the fan blade can be better studied,and the influencing factors of the fan blade ice coating growth are analyzed.It is important for the wind farm to prevent ice and deicing and safe operation.The paper mainly carried out numerical simulation and artificial ice coating test on the ice coating of NE-100 horizontal axis wind turbine blades.The paper establishes the two-dimensional airfoil geometry model of thewind turbine blade and studies the motion process of the supercooled water droplets.The collision coefficient and freezing coefficient of the water droplets on the wind turbine blade surface under different environmental parameters are calculated.The ice thickness of the wind turbine blade is obtained and the ice shape of wind turbine blades are drawn.The ice coating test of wind turbine blades was carried out in the artificial climate chamber,and the influence of relevant environmental parameters on the ice coating weight and ice thickness of the wind turbine blades was analyzed.The main research work and results are as follows:(1)A mathematical physical model of wind turbine blade icing is established.A two-dimensional geometric model is established for the airfoil at the blade tip of the wind turbine blade.The flow field of the fan blade air is calculated by Fluent software,and the motion track of the supercooled water droplet is obtained,and the movement of the water droplet is analyzed.The results show that the supercooled water droplets in the flow field mainly impact on the leading edge and the windward side of the fan blade.(2)The distribution law of the water droplet collision efficiency of the fan blade is calculated based on the Lagrangian method.The calculation results show that the increase of the flow velocity and MVD will increase the collision coefficiency of water droplets.The larger the flow velocity,the collision zone of water droplets moves from the windward face to the leeward surface;the larger the MVD,the collision zone of water droplets on the fan blade surface is bigger.(3)According to the Messinger ice accretion thermodynamic model,the thermodynamic equilibrium equation of blade ice coating is solved,and the distribution law of water droplet freezing fraction on the wind turbine blade surface is calculated.The calculation results show that the freezing fraction of water droplets at the stagnation point of the fan blade is the smallest,and it tends to increase along the windward and leeward surfaces of the blade.In some areas,the freezing fraction of water droplets reaches a saturation value of 1,indicating that the ice coating type is rime ice.The decrease in ambient temperature,liquid water content and the incoming flow rate will increase the freezing fraction of water droplets.(4)Based on the calculation of the water droplet collision coefficiency and the freezing fraction of the wind turbine blade,the ice thickness of the wind turbine blade is calculated,and the ice shape of the fan blade is drawn.The calculation results show that the greater the flow velocity,the lower the ambient temperature and the higher the liquid water content,the greater the thickness of the ice on the surface of the wind turbine blade.(5)The effect of environmental parameters on the ice coating of wind turbine blades was studied in an artificial climate chamber.The experimental results show that the ice coating on the wind turbine blade is mainly concentrated at the tip of the blade;the ice at the blade root is less covered with ice and is not affected by environmental factors;the ice weight and ice thickness gradually increase from the root to the tip of the blade;the greater the flow velocity,the larger the liquid water content and the lower the test temperature,the greater the ice coating weight and the thickness of the ice coating.(6)Comparing the ice thickness of the wind trurbine blade obtained by the ice test and the numerical simulation,it is concluded that considering the effect of the ice-free test on the flow of unfrozen water along the blade and the shutdown in a shorter time,the thickness of the wind turbine blade obtained by the numerical calculation is larger. |
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