Analytical And Experimental Researches On The Airfoil Surface Adhesion Strength Of Ice For Wind Turbine Blade

In the background of the " peak carbon dioxide emission and carbon neutrality," renewable energy has ushered in new development opportunities.As one of the most successful renewable energy in commercial operation,wind power attracts more and more attention.However,wind turbines often face disastrous weather such as cold waves,snowstorms,and frost in high latitudes and high elevations where wind energy resources are better than others.The ice accretion on the surface of the wind turbine blades reduces the output power and even causes safety accidents.Scholars have carried out some studies and explorations in researching anti-icing and de-icing methods for the wind turbine.However,there is little research on the principle of icing adhesive on the blade surface.To find out the adhesive characteristics of ice accretion on the blade surface is the key to researching the anti-icing and de-icing technology of wind turbines.Therefore,to explore the adhesive characteristics of ice accretion on the surface of wind turbine blades,the following studies are carried out based on theoretical analysis and icing wind tunnel experiments.(1)A theoretical model of icing adhesion strength accretion on the surface of cryogenic materials is established.The micro-morphology characteristics of the material surface are abstracted and simplified,and the material surface micro-morphology model is proposed.Based on the microtopography model of the material surface,the mechanical properties between the ice and substrate during icing are analyzed.Based on mechanical adhesion theory,the thermal deformation characteristics of materials,and the tribological principle,the interaction relationship among the parameters is determined,and the icing adhesion strength model is established.The model characterizes the effects of environmental and material parameters on the adhesion strength of ice accretion on low-temperature materials surface and provides an analytical basis for the experimental study.(2)The distribution law of icing on the blade surface of the wind turbine is studied by experiment.The icing test scheme of the wind turbine blade is designed,and the icing test is carried out using the reflux icing wind tunnel.The evaluation method of icing distribution on the blade surface is established.The effects of icing time length,ambient temperature,and wind speed on the icing distribution of blade surface are analyzed quantitatively.The experimental results show that the ice thickness on the blade surface increases with the increase in icing time length and the icicle generates on the lower airfoil.When the ambient temperature is high,the ice type on the blade’s surface is glaze ice.The ice thickness on the blade surface increases with the decrease in ambient temperature,and the ice type changes from glaze ice to rime ice.Under the same icing time length and ambient temperature,the ice thickness increases slightly with the increase of wind speed,and the ice grows from the leading edge of the blade to the trailing edge.(3)Experimental research on the adhesion strength of ice accretion on the wind turbine blade surface is carried out.A measurement system of ice adhesion strength for the wind turbine blade is designed and built.The experiment studied the icing adhesion strength on the blade surface under different icing time length,ambient temperature,and wind speed conditions.The experimental results show that the adhesion shear stress of ice on the blade surface increases with the decrease in ambient temperature.The adhesion shear stress of ice on the blade surface decreases with increased wind speed.In addition,the icing time length has little effect on the adhesion shear stress.When the icing time length increases,the adhesion shear stress of ice on the blade surface increases slightly,and the average is about 293.97 k Pa.The icing wind tunnel experiment and theoretical analysis results of the adhesion strength of ice are compared.The comparison results show that the theoretical calculation results of the model can reasonably predict the changing trend of adhesion shear stress with environmental parameters.However,the theoretical calculation value is higher than the experimental value.The difference may be from interface defects between ice and the substrate,the stress distribution in the ice,the shedding form of the ice,and the hydrophobicity of the material surface.The theoretical calculation and experimental results show that the temperature difference of blade surface has a more significant effect on the adhesion strength of ice than the volume expansion coefficient and the bulk modulus.The temperature difference is a critical factor that affects the adhesion shear stress of ice on the blade surface.