Research On The Influence Of Winglets On Aerodynamic Characteristics Of Unmanned Aerial Vehicles

Winglets can suppress wingtip vortex,thereby reducing the induced resistance and improving the lift-to-drag ratio.At present,winglets are widely used in commercial airplanes and increasingly appearing on UAVs.For flying-wing UAVs,due to the elimination of the empennage,the role of winglets is even more important,so it is necessary to study the influence of winglets on UAVs.In this paper,according to the flying-wing UAV model of our research group,an aerodynamic analysis method based on CFD(Computational Fluid Dynamics)technology is established in the following process.Based on the basic principles of computational fluid dynamics,the secondary development technology of CATIA is used to implement parametric modeling of the UAV,and the automatic generation of computing grids is achieved through Pointwise's Glyph scripts,and the calculation results are automatically derived through the batch operation of the Fluent software.Based on the two flow field simulation examples of the NACA 0012 airfoil and the ONERA M6 wing,the distribution of pressure coefficients is calculated.The influence of the turbulence model and the grid density on the calculation results are analyzed.The results are compared with the experimental results to verify the accuracy of the aerodynamic analysis method based on the CFD technology.Based on the vortex lattice method,a MATLAB program is written to calculate the aerodynamic performance parameters such as lift,induced drag and wing root bending moment of the UAV at a low angle of attack,and the load distribution on the whole UAV is analyzed.For the flying-wing UAV model,using the aerodynamic analysis method based on CFD technology,combined with the vortex lattice method,the influence of a winglet on the aerodynamic characteristics of the UAV is analyzed through grid-independence verification.Based on the aerodynamic analysis method,the process of analyzing the influence of each parameter of the winglet on the aerodynamic characteristics of the UAV is established,and the influence of each geometric parameter of the winglet on the lift-to-drag ratio of the UAV is analyzed,finally aerodynamic shape optimization design of winglets of the UAV is implemented.