Design of Trailing Edge of a Rigid-flexible Chord-Wise Variable Camber Wing

doi:10.12382/bgxb.2022.0301

Abstract

Abstract:

In order to realize the continuously chord-wise camber change of a wing under driving control, with material deformation ability considered,, an airfoil with hybrid (rigid-flexible) variable trailing edge is proposed. Through the geometric analysis of the mean camber line of the trailing edge, the parametric model of variable camber configuration is established. Taking lift-drag ratio as the optimization objective, the optimal bending angle of the rigid section and the optimal curve of the flexible section are calculated. The lift coefficient, lift-drag ratio and other aerodynamic characteristics of the rigid-flexible airfoil and traditional rigid airfoil are compared at different angles of attack by CFD calculation. When the lift required by the unit span during cruise is taken as the optimization objective, the bending angles and deformation modes of two different trailing edge airfoils are solved respectively in low-speed cruise condition and landing condition. The pressure distribution, velocity distribution and separation position of the two bending forms are compared. A wing model with rigid-flexible variable trailing edge based on the optimized configuration is fabricated and the deformation capability testing is conducted. The results show that: the rigid-flexible trailing edge airfoil has higher lift coefficient, lift-drag ratio and better aerodynamic characteristics in same deflection angle; in the same flight condition, the rigid-flexible trailing edge airfoil has a smaller deflection angle and a more backward separation point, so it has a higher aerodynamic efficiency. The rationality of the flexible wing rib structure and skin design has been verified through deformation capability testing.

Key words: chord-wise variable camber wing, mean camber line of airfoil, rigid-flexible, lift-drag ratio, variable trailing edge wing model

CLC Number:

V224⁺.5

XIN Tao, LI Bin. Design of Trailing Edge of a Rigid-flexible Chord-Wise Variable Camber Wing[J]. Acta Armamentarii, 2023, 44(8): 2465-2476.

Figures/Tables 23

Fig.1 Structure layout of wing rib trailing edge

Fig.2 Mean camber line of trailing edge of airfoil

Table 1 Airfoil state and operating parameters

攻角/ (°)	马赫数	空气密度/ (kg·m³)	空气动力黏度/ (Pa·s)	雷诺数
8	0.2	1.205	1.78938×10^-5	4.58×10⁶

Fig.3 Optimization process of optimal airfoil

Fig.4 Optimal configuration of flexible rib

Fig.5 Comparison of hybrid rib and cantilever rib

Fig.6 Computational grid

Fig.7 Comparison of lift coefficient

Fig.8 Comparison of CL/CD coefficients

Table 2 Configuration of rigid-flexible trailing edge of airfoil

飞行工况	攻角/ (°)	马赫数	高度/ m	刚性偏角/(°)	柔性偏角/(°)
低速巡航	4	0.35	100	0	8.7
降落工况	8	0.2	0	3.78	15

Fig.9 Comparison of pressure nephograms of low-speed cruise

Fig.10 Comparison of velocity nephogram and streamline of low-speed cruise

Fig.11 Comparison of pressure nephogram of landing

Fig.12 Comparison of velocity nephogram and streamline of landing

Fig.13 Comparison of pressure coefficients of upper and lower surfaces of airfoil

Fig.14 Topology optimization process based on load path method

Fig.15 Schematic diagram of topology optimization design area of flexible section

Fig.16 Rigid-flexible trailing edge structure

Fig.17 Pressure coefficient of rigid-flexible variable camber airfoil

Fig.18 Skin in pull mode in rigid section

Fig.19 Connecting structure of upper and lower wing surfaces at the end of wing rib

Fig.20 Rigid-flexible variable trailing edge model

Fig.21 Deformation shape of trailing edge under different driving conditions

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