Simulation And Experimental Researches On Anti-icing And De-icing Of Wind Turbine Blade Based On Ultrasonic Micro-vibration

The wind energy has many advantages in the electric power generation,such as being clean,no pollution and sufficiency.Therefore,it inspires the rapid development of the wind power industry.However,with the deterioration of the global environment,the extreme weathers often happen,such as lower temperature,humidity and freezing rain.They usually present in the high-altitude and high-latitude regions.In these regions,there is sufficient wind energy and high utilization rate,which are suitable to set up wind turbines.However,the icing accretion often presents on the wind turbine blade surface due to low temperature and freezing rain.The icing event will damage the aerodynamic profile of the wind turbine bade,which leads to the decrease in power generation efficiency.In addition,the icing event also make the weight of the wind turbine blade increase,and damage the dynamic balances of rotor and mechanical transmission system.It decreases the reliability and safety of wind turbine.Therefore,exploring the deicing technology of the wind turbine blade has the high application value.In this paper,the ultrasonic deicing technology has been researched based on the vibration deicing mechanism.The ultrasonic vibration deicing method has the characteristics of no noise,small vibration amplitude and low energy consumption.The simulation method and experimental method are used to carry out the researches on the ultrasonic vibration de-icing of the icing plate and the icing wind turbine blade.The main purpose is decreasing the thickness of the ice layer covered in blade surface,diminishing the bond strength of the ice layer or removing the ice layer,which keeps the performance of the wind turbine.The researches provide the theoretical and experimental foundations for the application of the ultrasonic vibration de-icing technology to the wind power industry.The key research contents are listed as following.(1)In this paper,the effects of ultrasonic vibration on the adhesive characteristics of icing plate are studied by simulation method.The effect of the ice layer thickness of the aluminum icing plate on the first vibration mode and its natural frequency is simulated by ANSYS.The variations of the maximum shear stress,the de-icing area ratio and the distribution of shear stress at the adhesive interface with excitation frequency are researched by harmonic analyses.The simulation results show that the distribution of the shear stress at the adhesive interface significantly affects the adhesion of the ice layer.When the positive shear stresses and the negative ones alternately distribute,the de-icing area ratio is highest,and the capability of ultrasonic anti-and de-icing method is excellent.Based on the above research results,the effects of structure size of the aluminum icing plate and excitation voltage on the maximum shear stress at the interface are researched.It is found that there is the optimum size of PZT patch as the size of aluminum icing plate is constant when the size of the aluminum sheet is constant.In addition,the de-icing area can further increase along with excitation voltage.(2)A device for measuring the adhesive torque of the ice layer covered in icing plate is designed.An experimental system with ultrasonic vibration function is designed and built.For calculating the adhesive shear stress of the ice layer,one mathematical model is established.The experimental results show that the adhesive shear stress of the ice layer decreases significantly under the excitation of the ultrasonic vibration.The minimum adhesion is 9.6% in the absence of ultrasonic state.The excitation frequency is the same as that which can generate large shear stress at the interface in theoretical calculation.The experimental results are consistent with the theoretical results,which verify the anti-ice ability of ultrasonic micro-vibration.(3)The theoretical and experimental researches on the ultrasonic anti-and de-icing of the wind turbine blade are carried out.The vibration modes and natural frequencies of the wind turbine blade are analyzed by ANSYS.The sixty-fifth vibration mode is selected as the de-icing mode,and the positions and the sizes of PZT patches are decided.Then the vibration modes and natural frequencies of the wind turbine blade with the ice layer and the PZT patches are also analyzed.(4)A wind turbine blade sample is designed and manufactured,and the impedance and natural frequencies of it are measured by impedance analyzer.An icing wind tunnel system is also built in this paper.The experimental parameters in the icing wind tunnel are calibrated.A device for measuring the adhesion of the ice layer covered in icing wind turbine blade is designed.Under the excitation of the ultrasonic vibration,the effects of the parameters,including the angle of attack(AOA),the wind speed and the experimental temperature,on the dimensionless icing areas,the stagnation thickness and the icing shape are researched.Measured the effect of ultrasonic vibration on the adhesion of ice layer.The experimental results show that under ultrasonic vibration,the minimum amount of ice and the ice adhesion on the blade surface are 59.33% and 60.25%respectively,and the ultrasonic vibration has a certain anti-and de-icing ability for the wind turbine blade.