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.

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.

scholarly journals Aeroelastic Optimization Design for High-Aspect-Ratio Wings with Large Deformation

2017 ◽  
Vol 2017 ◽  
pp. 1-16
Author(s):  
Changchuan Xie ◽  
Yang Meng ◽  
Fei Wang ◽  
Zhiqiang Wan
Keyword(s):  
Aspect Ratio ◽  
Large Deformation ◽  
High Aspect Ratio ◽  
Optimization Design ◽  
Geometrical Nonlinearity ◽  
Computing Time ◽  
Wind Tunnel Test ◽  
Lattice Method ◽  
Wing Model ◽  
Design Variables

This paper presents a framework of aeroelastic optimization design for high-aspect-ratio wing with large deformation. A highly flexible wing model for wind tunnel test is optimized subjected to multiple aeroelastic constraints. Static aeroelastic analysis is carried out for the beamlike wing model, using a geometrically nonlinear beam formulation coupled with the nonplanar vortex lattice method. The flutter solutions are obtained using the P-K method based on the static equilibrium configuration. The corresponding unsteady aerodynamic forces are calculated by nonplanar doublet-lattice method. This paper obtains linear and nonlinear aeroelastic optimum results, respectively, by the ISIGHT optimization platform. In this optimization problem, parameters of beam cross section are chosen as the design variables to satisfy the displacement, flutter, and strength requirements, while minimizing wing weight. The results indicate that it is necessary to consider geometrical nonlinearity in aeroelastic optimization design. In addition, optimization strategies are explored to simplify the complex optimization process and reduce the computing time. Different criterion values are selected and studied for judging the effects of the simplified method on the computing time and the accuracy of results. In this way, the computing time is reduced by more than 30% on the premise of ensuring the accuracy.

On the Pressure Distribution Round Certain Aerofoils of High Aspect Ratio

1926 ◽  
Vol 30 (182) ◽  
pp. 129-141
Author(s):  
D. M. Wrinch
Keyword(s):  
Aspect Ratio ◽  
Cross Section ◽  
High Aspect Ratio ◽  
Special Interest ◽  
Cylindrical Body ◽  
The Body ◽  
The Other ◽  
Two Dimensional ◽  
Reasonable Accuracy ◽  
Lifting Force

The development of aerodynamical research into the usefulness of wing profiles of various types for aerofoils of high aspect ratio lends special interest to new results in two-dimensional hydrodynamics relating to the motion of a perfect fluid in the presence of a cylindrical body, especially in the case when the curve of cross-section of the body possesses only a smali amount of camber and is cusped at one end and rounded at the other.The possibility of formulating a theory which represents with reasonable accuracy the actual motions of aerofoils of high aspect ratio in a stream of air, when the air it taken to be inviscid, depends, of course, essentially in the first place on finding motions in which there is a force on the body at right angles to the direction of streaming. No theory which omits to produce this lifting force can give an account of the actual motions of aerofoils which is even approximately satisfactory.

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.

The effect of the high-aspect-ratio design parameters on ITER containment structures

2002 ◽  
Author(s):  
B.E. Nelson ◽  
D.L. Conner ◽  
P.J. Fogarty ◽  
G.H. Jones ◽  
D.C. Lousteau ◽  
...  
Keyword(s):  
Aspect Ratio ◽  
High Aspect Ratio ◽  
Design Parameters

scholarly journals Quantitative comparison of 2D and 3D shock control bumps for drag reduction on transonic wings

2018 ◽  
Vol 233 (7) ◽  
pp. 2344-2359
Author(s):  
Feng Deng ◽  
Ning Qin
Keyword(s):  
Aspect Ratio ◽  
Incident Angle ◽  
Design Parameters ◽  
Comparative Performance ◽  
Cross Sectional ◽  
Shock Control ◽  
Design Variables ◽  
Natural Laminar Flow ◽  
Area Rule ◽  
2D And 3D

In this paper, the design spaces of the 2D and 3D shock control bumps on an infinite unswept natural laminar flow wing are investigated by adopting an optimization enhanced parametric study method. The design space spanned by the design variables are explored through a series of design optimization and their landscapes around the optima are revealed. The effects of the bump spacing, bump length, and Mach number are investigated respectively around the optima. The maximum cross-sectional area, bump incident angle, and aspect ratio are found to be important design parameters. The associated flow physics is discussed in relation to these parameters. The comparative performance of the 2D and 3D bumps are explained in the context of the transonic area rule. Two types of flow separation are identified by varying the bump aspect ratio at off-design conditions. It is concluded that the 2D and 3D shock control bumps can have nearly the same performances at optimal designs with similar cross-sectional areas. Some practical design principles and guidelines are suggested.

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

Topology Optimization of High Aspect Ratio Internal Cooling Channels As a Design for Additive Manufacturing

2020 ◽  
Author(s):  
Shinjan Ghosh ◽  
Jayanta S. Kapat
Keyword(s):  
Heat Transfer ◽  
Topology Optimization ◽  
Additive Manufacturing ◽  
Aspect Ratio ◽  
Gas Turbine ◽  
High Aspect Ratio ◽  
Design Parameters ◽  
Internal Cooling ◽  
Computational Domain ◽  
Pin Fin

Abstract High aspect ratio channels are a common internal cooling feature in Gas Turbine blades, mostly suitable for the trailing edge region or mid-chord regions. Traditionally such channels are fitted with rib-turbulators and/or pin-fin turbulators to augment heat transfer and prevent material failure. Highly efficient internal cooling of blades can improve the efficiency of a real Gas Turbine power cycle by tolerating higher Turbine Inlet Temperatures (TIT). Multi-physics Topology optimization (TO) has been employed in the current study to find optimized shape of these ducts, with an aim to increase heat transfer, while constraining the pressure drop across the channel. This method, commonly used in structural problems, is a novel topic of research when applied to fluid-thermal studies. Material distribution in the computational domain is varied by changing porosity value in each cell and thereby altering the fluid path and creating a conjugate heat transfer problem. Each cell has a value of Brinkmann porosity factor which either simulates a blockage, or a fluid region depending on a low or high value of this design variable. Hence the degree of freedom is high in this method, and there is no manual bias introduced, unlike in parametric shape optimization which is limited to a few design parameters. The unconventional geometries obtained as an end product of this optimization process can thus be an alternative to existing rib/pin-fin type of cooling geometries. The recent progress in additive manufacturing can now facilitate the manufacturing of complicated shapes. An in-house Open-FOAM solver has been used to carry out the process in only twice the amount of time compared to a regular RANS-CFD. 3-Dimensional rectangular channels with inlet aspect ratios of 4:1 and 8:1 have been considered as baselines with a constant inlet velocity. Resulting optimum geometries were found to have organic tree like branching arrangements of rib-like wall roughness and v-shaped structures.

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