| Blade is a key part of wind turbine to obtain wind energy,its structure determines the overall performance of wind turbine,and the design cost is about 1/3 of the total cost.Blsde element momentum theory is usually used in the design and analysis of blades.This theory analysis aerodynamic performance by dividing the blade into several interrelated blade element,however,it neglects the influence of the radial flow of the air flow among the blade elements.It is in large error in the analysis of the actual large size,strong wind and flexible blade aerodynamic load.With the trend of the large scale development of wind turbine blades,the aerodynamic elastic phenomenon caused by the length of blade and the flexible structure is becoming more and more obvious,which seriously affects the load distribution,the utilization of wind energy and the service life of the wind turbine.Based on this,this paper takes the typical Wind PACT 1.5MW wind turbine blade as the research object,analyzes the influence law of the radial flow,the blade deformation and the vibration on the blade load,and optimizes the design of the blade using the improved particle swarm optimization algorithm.Blade load analysis and optimization design has certain theoretical significance and practical engineering value for the design and improvement of large size actual fans.The specific work of the paper includes:(1)Considering the large size flexibility of the blade,a three-dimensional numerical simulation model of the coupling and uncoupled blade deformation is established,and the influence of the blade deformation on the aerodynamic load and the velocity distribution of the three dimensional wind field at the tip of the blade are analyzed.The twodimensional numerical model of blade is established at the cross section of 0.3R,0.75 R and 0.98 R,and the variation rule of aerodynamic load on blades under radial flow is analyzed.It is found that when the ratio of total blade deformation to blade length is greater than 0.0304,the main factor that affects blade load is blade deformation.When the value is(0.0135,0.0304),the blade deformation and radial flow both influence blade load,and when the value is less than 0.0135,the main factor is radial flow.(2)The blade vibration inducer was introduced,and the traditional blade momentum theory was modified to obtain the effect of blade wave and vibration frequency on blade load under different flow fields.It is found that the induced velocity of vibration is mainly in the direction of wave,and the direction of vibration is relatively small.When the wind speed reaches 12m/s,the induction speed of the two directions reaches the maximum,and the effect of the vibration on the blade load is maximum.(3)Based on the improved particle swarm optimization(PSO),a "sigmoid" function inertia weight adjustment method is proposed,and the blade is optimized by adjusting the position and thickness of the beam cap layer.The study shows that increasing the thickness of the beam cap and reducing the thickness of the vice beam cap can increase the blade section waving stiffness without changing the shape of the beam cap and material.Reducing the thickness of the main beam cap at the 0.6R~0.8R blade is also beneficial to the increase of the first wave frequency of the blade. |
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