Study On Stress Variation Of Small Wind Turbine Blade Under Wear

Whether the wind turbine blades can work normally is directly related to the power generation efficiency of the wind turbine.Due to China’s special geographical and climatic environment,wind turbine blades in Northwest China will have the problem of wind sand erosion.The influence of wind sand impact on blades in wind sand environment and the structural stability of blades after abrasion are two important problems in the study of wind sand erosion of wind turbine blades.In order to effectively solve the above problems,taking the micro model of wind turbine blade as the research object,the main parts of the blade are divided into three sections,and the wear degree of blade Level 3 is defined at the same time.The erosion wear test was carried out on XS-40 air jet sand carrying test-bed.Considering the erosion wind speed,erosion angle and the proportion of coarse sand in sand laden flow as variables,the orthogonal test is carried out to obtain the impact force of wind and sand on the blade and the variation law of impact force with each variable.Through the test,it was cleared that the erosion wind speed is the main factor affecting the blade stress The impact force obtained from the test is applied to the blade model for static analysis to confirm whether the aerodynamic load can replace the impact force of actual aeolian sand.Finally,the micro model of wind turbine blade is numerically simulated,the stress characteristics of wind turbine blade under different wear conditions are analyzed by sections,and the stress change trend and law of different blade positions under different wear degrees are given,and a verification test was carried out to verify the feasibility of the numerical simulation method.The results show that the force load on the wind turbine blade is related to the erosion speed,erosion angle and erosion particle size.Among them,the impact of erosion speed on the load is the largest.Compared with the stress obtained by applying impact load to the blade and aerodynamic load,aerodynamic load can be used to replace the impact force of wind sand erosion in practice.As the blade is worn and gradually intensifies,the wear area gradually spreads from the leading edge of the blade to the highest point of the windward surface,and the stress on the damaged blade is less than that on the blade without wear.The area with large stress changes from the position of the blade near the leading edge to the position near the trailing edge.With the intensification of wear,the position of this area will gradually close to the trailing edge.At the same time,regardless of the degree of wear,the stress at the damaged part of the blade will be greater than the surrounding stress.For the leaf segments at different distances from the leaf root,the gradient variation law of stress distribution is basically the same in each leaf segment.The overall stress of the blade decreases with the distance from the blade root,and the change can be basically divided into three parts,that is,under different wear degrees,the stress on the 0.3R-0.5R blade segment basically maintains a level;The stress of 0.5R-0.7R blade segment began to show a downward trend,but its change speed was small and the speed remained basically stable;The stress of 0.7R-the blade in the tip decreases obviously,and the decreasing speed increases gradually.According to the above results,it can be seen that the stress at the worn part of the blade will change greatly after wear,which is easy to form stress concentration,so it should be repaired as soon as possible.