| Under the action of the incoming flow load,the deformation of the blade gradually increases in the spanwise direction,and reaches the maximum at the blade tip.The development of wind turbine blade slenderness makes it easier for the blade tip to collide with the tower during operation;although the pre-curved blade can achieve ideal aerodynamic performance and reduce power loss at rated wind speed,but the pre-curved blade is only at rated speed.Under the wind speed,it can maintain a good aerodynamic shape and adapt to a narrow wind speed range.Through the research and optimization of the blade web structure,some new web structures have been proposed,including: three webs,circular webs,bionic leaf vein webs,etc.,but these web structures are more difficult to process in practice.large,and has a greater impact on the blade weight.Because the I-beam structure has outstanding mechanical properties and simple structural form,it is easy to process while improving the bending resistance of the structure.Therefore,based on the web structure of the pre-curved blade,this paper designs a 1.5MW I-beam double-web pre-curved blade.The stress form and bending mechanism of the slab and main beam are studied;the deformation and stress distribution of different blades are compared and analyzed.In this paper,by analyzing the force characteristics of the blade,the two-dimensional airfoil section of the blade is equivalent to the mathematical model of the I-beam structure;a finite element model of the blade with I-beam web structure is established,and a total of 6 different blades are set for comparison.The modal analysis and static analysis were carried out for the six blades respectively,and the relevant data such as their natural frequency,blade deformation,and blade quality were finally obtained.The modal analysis shows that the blade with the I-beam web on the web is 40% L away from the pressure main beam(L is the length of the web on the airfoil section),and the first-order frequency of the blade is reduced by 3.25%.The maximum relative displacement of the first order decreased by 2.32%,and the mass increased by about 110kg;the static analysis showed that the blade tip deformation variable of the I-beam web at 40%L was reduced by 6.38% compared with the original blade,and the bending performance was better;Moreover,the maximum strain area of all blades is 60%L-70%L away from the blade root,which indicates that the bending of the blade leads to a great extrusion deformation of the blade in the maximum strain area.The above results show that the I-shaped plate installed between the upper and lower webs of the 1.5MW pre-curved blade can effectively reduce the deformation of the blade tip and the vibration frequency;effectively support the web,strengthen the shear resistance of the web,keep the relative position of the main beam stable,and improve the The bending resistance of the blade is best when laid at 40%L.In order to further study the influence of web thickness on blade deformation variables and explore the interaction between the web and the main beam,a "main beam-web box" model was established separately in this paper,and the web thickness parameter was used as a variable to set 8 A control group was compared,and the deformation amount,maximum stress and maximum strain of different structures under the same static load of the simplified "main beam-web box model" were compared and analyzed,and the occurrence area and occurrence mechanism were studied,and then the web in the structure was studied.role on the main beam.The force analysis of the web shows that the increase in the thickness of the upper and lower webs greatly improves the flexural performance of the "box-web box structure".The upper and lower webs of the blade are thickened with the sandwich layer,and the deformation amount decreases by 9.86 compared with No.1,this is because the PVC material plays the role of supporting the front and rear main beams and transmitting the shear force during the bending process of the structure.After the I-beam plate is thickened,the deformation of the structure is reduced by 19.60% compared with No.1.When the I-beam plate is too thin,the impact on the structural stability is small,indicating that the I-beam plate of a certain thickness has a significant impact on the stability of the box structure.This is because the thickened I-beam plate connects the upper and lower webs on the one hand,forming an "I" beam structure,which limits the relative displacement of the upper and lower webs in the X direction,so that the shape of the upper and lower webs can be maintained and reduced.The degree of extrusion deformation between the web and the main beam.In order to optimize the self-weight of the structure,part of the web plate was deleted and optimized.The data shows that the No.6 box structure only lays the I-beam plate in the "dangerous area" of the blade 60%R-75%R,and the blade has the largest shape.The variable decreased by 18.22% compared with No.1,which proves that the laying of I-beam slabs in the dangerous area has a small gap compared with the overall laying,but the weight is lighter.After the blade root web is removed,the deformation of the box structure increases sharply compared with the original blade,indicating that the absence of the blade root web leads to a sharp drop in the flexural performance of the structure,and the web at the blade root has a non-negligible effect on the overall stability of the blade.The force analysis of the main beam shows that there is a "short plate effect" in the "main beam-web box structure".If a main beam is not fully stressed,and the other main beam bears more pressure,Therefore,the web plays an important role in the process of transmitting the interaction force between the main beams;changing the ratio of the parameters of the layup angle of the suction main beam can improve its bending performance,an increase of 45° The ratio of the layup angle improves the compressive and bending deformation capacity of the suction main beam,reduces the structural deformation by 11.47%,and the effect is significant,which further confirms the existence of the "short plate effect" between the main beams.In this paper,a new type of I-beam web structure is used to optimize the1.5MW wind turbine blade,which improves the bending resistance of the blade and effectively reduces the blade deformation.The bending resistance mechanism of the I-beam web is analyzed,and the pressure is explained.The phenomenon of "short plate effect" between the main girder and the suction main girder further optimizes the main girder structure;it provides ideas and references for further research on improving the performance of blade structures. |
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