Non-linear aeroelastic analysis in the time domain of high-aspect-ratio wings: Effect of chord and taper-ratio variation

2016 ◽  
Vol 121 (1235) ◽  
pp. 21-53 ◽  
Author(s):  
A. Suleman ◽  
F. Afonso ◽  
J. Vale ◽  
É. Oliveira ◽  
F. Lau
Keyword(s):  
Aspect Ratio ◽  
High Aspect Ratio ◽  
Bending Moment ◽  
Equilibrium Solutions ◽  
Computational Framework ◽  
Wing Model ◽  
Aeroelastic Analysis ◽  
Non Linear ◽  
Time Marching ◽  
The Time Domain

ABSTRACTCommercial jets usually have relatively low-aspect-ratio wings, in spite of the associated benefits of increasing the wing aspect-ratio, such as higher lift-to-drag ratios and ranges. This is partially explained by the fact that the wing becomes more flexible by increasing the aspect-ratio that results in higher deflections which can cause aeroelastic instability problems such as flutter. An aeroelastic computational framework capable of evaluating the effects of geometric non-linearities on the aeroelastic performance of high-aspect-ratio wings has been developed and validated using numerical and experimental data. In this work, the aeroelastic performance of a base wing model with 20 m span and 1 m chord is analysed and the effect of changing the wing chord or the taper-ratio is determined. The non-linear static aeroelastic equilibrium solutions are compared in terms of drag polar, root bending moment and natural frequencies, and the change in the flutter speed boundary is assessed as a function of aspect-ratio using a time-marching approach.

Absolute Nodal Coordinate Formulation With Vector-Strain Transformation for High Aspect Ratio Wings

2020 ◽  
Vol 16 (1) ◽  
Author(s):  
Keisuke Otsuka ◽  
Yinan Wang ◽  
Kanjuro Makihara
Keyword(s):  
Aspect Ratio ◽  
High Aspect Ratio ◽  
Degrees Of Freedom ◽  
Absolute Nodal Coordinate Formulation ◽  
Lattice Method ◽  
Absolute Nodal Coordinate ◽  
Aeroelastic Analysis ◽  
Strain Transformation ◽  
Highly Nonlinear ◽  
Analytical Approaches

Abstract High aspect ratio wings are potential candidates for use in atmospheric satellites and civil aircraft as they exhibit a low induced drag, which can reduce the fuel consumption. Owing to their slender and light weight configuration, such wings undergo highly flexible aeroelastic static and dynamic deformations that cannot be analyzed using conventional linear analysis methods. An aeroelastic analysis framework based on the absolute nodal coordinate formulation (ANCF) can be used to analyze the static and dynamic deformations of high aspect ratio wings. However, owing to the highly nonlinear elastic force, the statically deformed wing shape during steady flight cannot be efficiently obtained via static analyses. Therefore, an ANCF with a vector-strain transformation (ANCF-VST) was proposed in this work. Considering the slender geometry of high aspect ratio wings, the nodal vectors of an ANCF beam element were transformed to the strains. In this manner, a constant stiffness matrix and reduced degrees-of-freedom could be generated while capturing the highly flexible deformations accurately. The ANCF-VST exhibited superior convergence performance and accuracy compared to those of analytical approaches and other nonlinear beam formulations. Moreover, an aeroelastic analysis flow coupling the ANCF-VST and an aerodynamic model based on the unsteady vortex lattice method was proposed to perform the static and dynamic analyses successively. The proposed and existing aeroelastic frameworks exhibited a good agreement in the analyses, which demonstrated the feasibility of employing the proposed framework to analyze high aspect ratio wings.

The effect of stiffness and geometric parameters on the nonlinear aeroelastic performance of high aspect ratio wings

2016 ◽  
Vol 231 (10) ◽  
pp. 1824-1850 ◽  
Author(s):  
F Afonso ◽  
G Leal ◽  
J Vale ◽  
É Oliveira ◽  
F Lau ◽  
...  
Keyword(s):  
Aspect Ratio ◽  
High Aspect Ratio ◽  
Nonlinear Behavior ◽  
Geometric Parameters ◽  
Torsional Stiffness ◽  
Design Parameters ◽  
Sweep Angle ◽  
Flutter Speed ◽  
Wing Model ◽  
Aspect Ratios

The increase in wing aspect ratio is gaining interest among aircraft designers in conventional and joined-wing configurations due to the higher lift-to-drag ratios and longer ranges. However, current transport aircraft have relatively small aspect ratios due their increased structural stiffness. The more flexible the wing is more prone to higher deflections under the same operating condition, which may result in a geometrical nonlinear behavior. This nonlinear effect can lead to the occurrence of aeroelastic instabilities such as flutter sooner than in an equivalent stiffer wing. In this work, the effect of important stiffness (inertia ratio and torsional stiffness) and geometric (sweep and dihedral angles) design parameters on aeroelastic performance of a rectangular high aspect ratio wing model is assessed. The torsional stiffness was observed to present a higher influence on the flutter speed than the inertia ratio. Here, the decrease of the inertia ratio and the increase of the torsional stiffness results in higher flutter and divergence speeds. With respect to the geometric parameters, it was observed that neither the sweep angle nor the dihedral angle variations caused a substantial influence on the flutter speed, which is mainly supported by the resulting smaller variations in torsion and bending stiffness due to the geometric changes.

Body Freedom Flutter Study and Passive Flutter Suppression for a High Aspect Ratio Flying Wing Model

2014 ◽  
Vol 608-609 ◽  
pp. 708-712 ◽  
Author(s):  
Yuan Dong Li ◽  
Xin Ping Zhang ◽  
Ying Song Gu ◽  
Zhi Chun Yang
Keyword(s):  
Aspect Ratio ◽  
Mass Balance ◽  
High Aspect Ratio ◽  
Center Of Gravity ◽  
The Body ◽  
Design Parameters ◽  
Wing Model ◽  
Design Variables ◽  
Optimization Study ◽  
Tip Mass

Normal mode and flutter analysis are conducted for a high aspect ratio aft swept flying wing model, and body freedom flutter is found to be the most critical aeroelastic instability for this air vehicle model. To determine the influence of various kinds of design parameters on BFF characteristics, eight factors are considered in the parametric study, i.e. wing vertical bending stiffness, weight and center of gravity of the wing root payload and the wing tip mass balance, wing half span, aft swept angle and the station of wing body blended line. After the parametric analysis, the mass and center of gravity of the wing root payload are selected as design variables, and the baseline model is utilized in the design optimization study subject to critical flutter speed constraint. Finally, the optimal mass balance design is suggested to suppress the body freedom flutter phenomenon passively and maximize the payload.

Limit-Cycle Hysteresis Response for a High-Aspect-Ratio Wing Model

2002 ◽  
Vol 39 (5) ◽  
pp. 885-888 ◽  
Author(s):  
Deman Tang ◽  
Earl H. Dowell
Keyword(s):  
Aspect Ratio ◽  
Limit Cycle ◽  
High Aspect Ratio ◽  
Wing Model ◽  
Hysteresis Response
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