Study On Large Wind Turbine Blade Structure Analysis And Lay-up Design

The proportion of wind power is more and more obvious in energy structure, and the super large wind turbine 5MW and over 5MW is the inevitable trend of wind power development. The blade of the super large wind turbine is much larger than the blade of the ordinary wind turbine. Glass fiber composite material can not meet the requirements of the blade strength and quality. Most of the super large wind turbine blades is made of glass fiber and carbon fiber composite material. Super large wind turbines need not only high material requirements and lower weight as much as possible, but also the strength requirements to reduce the cost.The wind turbine blade is an elongated flexible body, under the action of wind load will be deformed hardly. The blade of wind turbine is made of pre-bending type to make the blade has good aerodynamic performance after deformation. The pre- bending wind turbine blades can be offset by the deformation of the blades under the action of wind pressure load, which makes the blades have good aerodynamic performance under the action of aerodynamic load.In this thesis, The design of paving layer and the structure of the NH02₁.5MW wind turbine blades is be analyzed. In according to the analysis of the wind turbine blade structure by the way of fluid-solid coupling under rated condition, completing the composite layers design of blade; The wind pressure load under rated condition of the windward and leeward is calculated by using FLUENT software, and the pressure load is translated to the composite wind turbine blade to get the structure response of blade under the rated conditions; According to the analysis result, the blade layer structure strength and the composite blade modal was analyzed. Finally, natural frequencies and modal shapes of blade at the free state is solved.The contents of the thesis were as follows:1、NH02₁.5MW wind turbine blade model has been fished, The structural response of the blade in fluid-solid coupling at the rated operating conditions is analyzed by using ANSYS Workbench. The material of blade is structural steel. The results showed that under the rated condition, wind turbine blade will occur large deformation, the maximum deformation occurs at the tip of blade, the stress of the blade root and the part that is closed to the 1 / 4 part of blade tip is bigger.2、According to the results of fluid-solid coupling analysis, the composite wind turbine blade is established with the requirement of composite layer. In this thesis,double web blade model and single- double web blade model were established, single- and double web is a blade which the part that is closed to the 1 / 4 part of blade tip of the double web is converted into a single web, and layer and the main beam at the position where the single web begin remain unchanged.3、The wind turbine blade surface pressure load is solved by FLUENT. The numerical results show that the pressure differential of blade windward and leeward increases gradually along the direction of blade span. The pressure differential reaches maximum in the tip section of the blade. The portion of the blade tip is the main position to output power. The pressure load is translated to the composite blade surfaces, finally, the structural response of the two kinds of composite blades in the rated condition is analyzed. The results show that the deformation of single- double web blade and double web blade is lower than the deformation（1700mm）of pre-bending blade. The deformation（1582.2mm）of single- double web blade at the blade tip is larger than the deformation（1459.04mm）of double web blade slightly; The maximum stress（40.03326Mp） of single- double web at blade root is larger than the maximum stress（36.419MP）double web blade. Fiber has the good ability to transfer loads, and the maximum stress of the composite blade near tip is passed to the root of blade. The maximum stress value of the blade root of structural steel blade reach to 23 Mp. Compared with the maximum stress value of the blade root of structural steel blade, the maximum stress value of the blade root of composite material blade increased 74% and reached 40.03326 Mp, and meets requirements of strength according to the verification by Cai Wu stress criterion.4、ANSYS software was used for modal analysis of composite blades, and the natural frequencies and modal shapes of blades in free state were analyzed. The results show that the weight of single- double web blade reduces 6%, as to the part of tip blade is in rotational states, so reduce quality for super large wind turbine blade has a important significance; Low order frequency between single-double web blade and double web blade has little difference; The high-order frequency of single-double web blade is bigger than double web blade; In wind turbine blade design, usually,we only pay attention to the blade of low order frequency, so the design is reasonable.