Aerodynamic Analysis And Optimization Of End Plate Of Joined Wing

As an unconventional configuration, the joined wing layout is characterized by low structural weight, high strength and rigidity, low induced drag, big lift coefficient and good stability. The excellent performance has attracted extensive attention. The Joined wing aircraft collocates two pairs of wings: the front and the back wing are connected through the end plate. Therefore, the geometric parameters of the end plate has a great influence on the aerodynamic characteristics of the joined wing. Research object of this paper is the joined wing layout model, simulated by the CFD method. The parameters of end plate were improved and optimized based on the visual analysis and variance analysis of the orthogonal experiment design.The following tasks were accomplished in this paper:The first part of this article introduced the research background and significance of this thesis, and reviewed the research status from domestic and abroad of joined wing layout. According to the results, determined the research direction.Secondly, the thesis introduced the numerical calculation methods for the study,including the flow control equations, the equation of discrete and solving, turbulence model, boundary conditions and mesh division method. Then completed the mesh generation of 3D model and verified the reliability of the model in this numerical method.Thirdly, determined the basic layout of the joined wing according to the principle of aircraft design. Based on the basic layout study, studied the front wing sweep angle and the join point position, and discussed the effects on joined wing layout. Combined with the indicators of aerodynamic and structural, the best range of front wing sweep angle is 20°⁴0°, the best range of join point position is 0.7 times of the front wing half span.Fourthly, studied the relative height of front and back wings and the effects of end plate with different airfoil shape at aerodynamic characteristics of joined wing configuration aircraft. Computing data showed that with the increase of height of end plate, lift drag ratio increased firstly and then decreased, the static stability had kept rising. The lift to drag ratio was optimal with the height of the end plate is equal to 0.1times of the front wing half span. The cross section of the end plate with different airfoil having great influence on the aerodynamic performance of the joined wing. Comparedwith the diamond airfoil, the arched airfoil end plate had more advantageous to the lift drag ratio with the same upwind surface area. When the maximum thickness of the end plate is locate in the second half part, the drag of the end plate was smaller. The end plate with anti-EPPLER479 airfoil cross section could improve the lift drag ratio, and would be controlled better.Finally, studied three different angle parameters（camber angle, deflection angle and axial angle with 5 angles:-10°、-5°、0°、5°、10°） of end plate through the orthogonal experiment method. Selected the orthogonal table L25（56）, which has 25 angle parameter configuration combination. The results was determined the optimal combination A₂B₅C₁ with camber angle-5°、deflection angle 10°、axial angle-10° by the direct observation method. The thesis conclude that deflection angle was the main factor for influencing the lift drag ratio and pitching moment compared with the camber angle and the axial angle through analysis and the experiment, and the optimized model had higher lift-drag ratio and better static stability compared with the reference model.