Structural Design Of Large Horizontal Axis Wind Turbine Blade Based On Fluid-structural Interaction

With the development of wind power technology,the large scale development of wind turbine and the single unit capacity increasing,the size of the blade is larger and larger and its structure is also more flexible.The interaction effect of blade aerodynamic and structure will be more obvious on blade load and power when the radius of wind wheel increasing.The interaction makes the deformation of the blade section.Then the lift resistance will change and the actual running power of the wind turbine can't reach the design power.The change of the blade load which interaction effect caused intensifies the vibration of the blade.It can cause the fatigue damage to the blade even the irreparable destruction of the machine,which is not conducive to the safe operation of the unit.Therefore,the interaction effect of blade aerodynamic and structure can not be ignored in the design of large wind turbine blade.The numerical simulation method can be used to simulate the fluid-structural interaction characteristics in the early design stage.According to the interaction characteristics of blade,the design of the cross section and the design of the layer will reduce the interaction deformation when blade meeting the stiffness and strength at the same time in operation.Then it will reduce the vibration and make the blade run to the design power.At the same time,we will reduce the blade quality as much as possible to reduce the cost of the blade and improve the market competitiveness.The main contents of this paper include the following aspects:1?According to the design method of large wind turbine blade,we will choose the reasonable design method,the design flow and the C language programming to realize the aerodynamic configuration design of 8MW wind turbine blade.At the same time,the load is calculated at different working conditions.The results show that the aerodynamic force along the blade increases first and then decreases,and the max output position of the blade is at 72%.The aerodynamic shear force and bending moment at root of blade are the largest along the blade,and the aerodynamic shear force and bending moment of the blade decrease gradually.2?According to the principle of fluid-structural interaction and its control equations.Based on the workbench platform,the fluid-structural interaction characteristics of 8MW horizontal axis wind turbine blade at different working conditions are simulated and the results are analyzed.The results show that the wind pressure increases with the increase of wind speed.The wind wheel surface pressure reaches the maximum when the maximum wind speed.At the same time,the stress concentration point of the blade is closer to the root.The blade stress mainly concentrated in the root and tip from root to tip 60%.3?According to the fluid-structural interaction characteristics of the blade,we will choose the reasonable design of blade section including beam position and beam form.The results show that the 35% of beam position is more suitable when the large wind turbine blade is using single beam.In the case of double beam,the location of the two beams is more suitable for the distribution of 20% and 50%.In order to reduce the deformation of the blade caused by the interaction effect,large wind turbine blades should be made of double beam.4?Compare the advantages and disadvantages of the commonly materials of large wind turbine blades and select the reasonable material.According to the fluid-structural interaction characteristics of the blade,the design of the layer is carried out.The reasonable laying angle,the sequence of the layer and the proportion of layer in each angle are determined.In order to reduce the stress between layers,the 0°and 90 °,45°and-45°of the layer should not be placed continuously.The blade structure performance is better when the 45° layer accounted for the total number of about 58%.5?Finite element analysis of the designed blade based on ANSYS software are used to determine its quality and structural characteristics.It includes blade deformation,natural frequency,vibration mode and maximum equivalent stress.Finally,it will check the design results.