Numerical Analysis On The Aerodynamic Characteristics And Crack Propagation Mechanism Of Wind Turbine Blade

Wind power, as one of clean and renewable resources has been greatly developed underthe background of the environment pollution, limited fossil fuel resources and greatlyimproved wind power technology. In the face of the demand for large-scale development ofthe wind turbine, it’s necessary to further upgrade the blade design to improve the utilizationrate of the wind energy and ensure safe and reliable operation of the composite material blade.To solve these problems, Computational Fluid Dynamics (CFD) theory was used in thispaper to simulate the blade flow field. Based on the flow field calculation results, strengthfailure analysis was done for the composite material blade, and crack propagation researchwas made near the blade root. The analyses of the aerodynamic performance of blade and itscrack propagation characteristics can serve as a theoretical basis for optimizing the windturbine blade design, as well as provide new ways for predicting the residual life of thecomposite material blades and analyzing the reliable operation of the blade.Above all, Wilson wind turbine blades optimization design method was adopted tocomplete the design of1.5MW wind turbine multi-airfoils blade. In the process ofestablishing the three-dimensional blade entity model, UG NX secondary developmenttechnology was used to improve work efficiency. Sliding mesh technology was used toestablish a finite element model of the flow field, and an analysis of9constant velocitymodels, including cut-in wind speed and rated wind speed, and gust model by CFX fluidanalysis software gave an introduction to wind turbine torque and the characteristics of itspower output. Compared with the known data, all these analyses proved that the simulationresults are true. Under different working conditions, the flow field pressure, velocity and staticpressure were analyzed, and the pressure distribution characteristics on the surface of the bladewere summarized. In particular, the high turbulence phenomenon near the blade roots providesreference for raising the aerodynamic performance of the wind turbine blade.Aerodynamic load was brought to bear on the blade based on the fluid-solid interactiontheory. In the process to study the tensile stress, shear stress and modal shape of the bladeunder the different working conditions with integrated multiple loads, it’s found that shearstress near the blade root is relatively large, and it greatly increases with the rising of the wind speed. Meanwhile, violent vibration occurred in the tenth mode of the blade. In combinationwith the strength criterion of the composite material, it’s discovered that failure is prone tooccur near the blade root, and this is consistent with the real condition of blade fracture failure.On account of the numerical results, crack model was loaded in the most vulnerable location,and the stress intensity factors of the different sizes of the cracks under different workingconditions were worked out, showing that there is hardly any connection between the initialcrack size and crack propagation, but crack propagation is significantly promoted with therising of the wind speed, which is consistent with the test result in the related references. Theresults in this paper can provide a reference for the blade life estimation and new methods forthe reliable research of the composite material.