| The exploitation of fossil energy,energy reserves and environmental pollution crisis have become important challenges facing humanity.As a large reserve of renewable clean energy,wind energy has become the target of all countries in the world.The wind power generation equipment of wind farms in inland and offshore areas has been fully loaded.In order to collect more wind resources,countries around the world have turned their attention to alpine wind farms and offshore wind farms.The lower environmental factors of wind farm construction have an important impact on the operation,protection and maintenance of wind power generation equipment.As one of the most important parts of wind power generation equipment,different types of blades behave differently under different environmental factors,so ensuring their safe and efficient operation is the main work of the staff.Wind turbine icing is the most common accident in low temperature environment.The different effects of various environmental parameters on blade icing are studied to provide theoretical support for wind turbine anti-icing and deicing.In this paper,the characteristics of wind turbine icing are mainly studied from the micro and macro aspects.From the micro perspective,the flow state of droplets on the blade surface is observed and the dynamic impact characteristics are analyzed by studying the impact process of two-dimensional airfoil and large water droplets;The macro perspective is to analyze the influence of parameters by analyzing the icing characteristics of three-dimensional wind turbine blades under different parameters.The main contents of this study are as follows:In the first part,by establishing a two-dimensional model of a wind turbine blade,the dynamic characteristics of large water droplets impacting an airfoil are studied,and the mechanism of water droplet breakage is studied.When water droplets flow on the airfoil surface,they are subjected to aerodynamic forces and resistance from the airfoil surface.The water droplets undergo three processes: impact,spreading,and detachment;The flow state of water droplets on the four airfoils S804,S805 a,S809,and S810 is different,which is related to the geometric data of the airfoil.Through the research results,it is found that the shortest flow time of water droplets on the S805 a airfoil is 0.0436 seconds,and they first leave the airfoil,showing the best fluidity;The hydrophilicity and hydrophobicity of the coating on the leading edge of an airfoil also have a significant impact on the impact characteristics of water droplets.When the coating exhibits hydrophilicity,the water droplets can complete the flow from the leading edge to the trailing edge of the airfoil.When the coating exhibits hydrophobicity and superhydrophobicity,the water droplets will pop out of the airfoil after a short distance due to the wetting angle after impact,leaving the airfoil near the leading edge of the airfoil;The research results show that the flow time of water droplets on the surface of the hydrophilic coating of the airfoil S805 a is 0.044 s,the flow time of the hydrophobic coating is 0.0145 s,and the flow time of the superhydrophobic coating is 0.0095 s.Moreover,only when the hydrophilic coating water droplets detach from the trailing edge of the airfoil,the hydrophobic and superhydrophobic coatings have separated in the leading edge position region,with a time reduction of about 67% and 78%,and a flow distance reduction of about 2/3,The performance of three different hydrophilic and hydrophobic coatings on three airfoils is consistent;The hydrophilic and hydrophobic properties of the airfoil surface coating can greatly reduce the flow distance of water droplets on its surface,providing convenience for anti ice work.In the second part,inland wind farms,coastal wind farms,and alpine wind farms are the three most common wind farms for wind turbine installation.The icing characteristics of wind turbines in various environments are important evidence for objectively evaluating the safety and stability of wind farms.By establishing a three-dimensional model of wind turbine blades,NREL Phase VI dual blade model is used to study the icing characteristics;The research results show that the windward side of a wind turbine blade is a positive pressure distribution area,while the leeward side is a negative pressure distribution area.The water droplet collection coefficient is concentrated in the central axis area of the blade.The distribution characteristics of the icing area are: concentrated windward side,wide coverage area,and scattered and loose leeward side;Ice formation is severe at the tip,cylindrical section,and root of the blade.The third part,the full load of inland wind farms,takes alpine wind farms as the main research object.The characteristics of alpine wind farms are rich in wind energy resources,remote from other activities,high wind speed,high liquid water content in the air,and frequent changes in wind direction.The wind speed is much higher than the standard wind speed.The research results show that as the wind speed increases,the pressure difference between the windward side and the leeward side of the blade gradually increases,especially the negative pressure on the leeward side increases sharply,which affects the smooth operation of the blade and degrades its dynamic characteristics;The water droplet collection coefficient gradually increases from 0.298 to 0.306 at wind speeds of 25 m/s to 30 m/s,but after 35 m/s,there is a downward trend of 0.299,which is caused by excessive pressure differences on both sides of the blade;After 10 minutes of ice formation,both the ice formation area and the total ice formation mass on the blade surface increase with the increase of wind speed.The total ice formation mass is 10.78 kg when the wind speed is 25 m/s,and 19.98 kg when the wind speed is 40 m/s.With each increase of wind speed of 10 m/s,the total ice formation mass increases by about 4-5 kg;The thickness of the ice layer on the surface of the blade increases,and the regions with the most severe ice formation are the cylindrical segment and the blade root region.The ice layer is the first to cover,and the ice layer is the thickest;After icing,the dynamic performance of the blade further deteriorated,and the normal rotation of the blade was affected.The content of liquid water in the air and the angle of attack are also the main parameters that affect blade icing,neither of which has a significant impact on the calculation of the flow field of the blade.The increase in the angle of attack slightly increases the water droplet collection coefficient,while the content of liquid water has almost no impact.The distribution of icing areas is mainly concentrated in the cylindrical section and the root region of the blade.The amount of ice decreases slightly with the increase in the angle of attack,from 7.56 kg at 0 ° angle of attack to 7.27 kg at 9 ° angle of attack;The amount of ice formation increases by 5kg for each 1g/m3 increase in the liquid water content in the air.The results show that the increase of wind speed and liquid water content will exacerbate the icing situation of the blades,and the icing area,ice layer thickness,and total ice mass will increase.Choosing reasonable environmental parameters is the key to ensuring the efficient and safe operation of wind turbines.Figure [80] Table [4] Reference [81]... |
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