Analysis and Design of Wings and Wing/Winglet Combinations at Low Speeds

Chattot, Jean‐Jacques

doi:10.2514/6.2004-220

Cited by 25 publications

(27 citation statements)

References 7 publications

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“…Note that the normal force model has historically been used to represent the un-stalled 2D aerofoil lift coefficient of wings operating at high angles of attack within the helicopter and fixed wing aerodynamics literature [34,35]. Later, various models based on the normal force assumption have been widely used to represent the quasi-steady aerodynamics of revolving/flapping wings [15,18,36 -41].…”

Section: Normal Force Modelmentioning

confidence: 99%

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The role of the leading edge vortex in lift augmentation of steadily revolving wings: a change in perspective

Nabawy¹,

Crowther²

2017

J. R. Soc. Interface.

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The presence of a stable leading edge vortex (LEV) on steadily revolving wings increases the maximum lift coefficient that can be generated from the wing and its role is important to understanding natural flyers and flapping wing vehicles. In this paper, the role of LEV in lift augmentation is discussed under two hypotheses referred to as 'additional lift' and 'absence of stall'. The 'additional lift' hypothesis represents the traditional view. It presumes that an additional suction/circulation from the LEV increases the lift above that of a potential flow solution. This behaviour may be represented through either the 'Polhamus leading edge suction' model or the so-called 'trapped vortex' model. The 'absence of stall' hypothesis is a more recent contender that presumes that the LEV prevents stall at high angles of attack where flow separation would normally occur. This behaviour is represented through the so-called 'normal force' model. We show that all three models can be written in the form of the same potential flow kernel with modifiers to account for the presence of a LEV. The modelling is built on previous work on quasi-steady models for hovering wings such that model parameters are determined from first principles, which allows a fair comparison between the models themselves, and the models and experimental data. We show that the two models which directly include the LEV as a lift generating component are built on a physical picture that does not represent the available experimental data. The simpler 'normal force' model, which does not explicitly model the LEV, performs best against data in the literature. We conclude that under steady conditions the LEV as an 'absence of stall' model/mechanism is the most satisfying explanation for observed aerodynamic behaviour.

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Section: Normal Force Modelmentioning

confidence: 99%

“…The 2D form of normal force model is expressed as the potential flow model multiplied by a cos a term [34,35]:…”

Section: Normal Force Modelmentioning

confidence: 99%

The role of the leading edge vortex in lift augmentation of steadily revolving wings: a change in perspective

Nabawy¹,

Crowther²

2017

J. R. Soc. Interface.

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“…A test case with exact solution, based on the Lifting Line theory and a 2-D lift coefficient given analytically by C l (a) = p sin 2a, has shown that this approach gives excellent results for the complete range of as, from zero to p 2 [10].…”

Section: Algorithm For High-amentioning

confidence: 93%

Helicoidal vortex model for steady and unsteady flows

Chattot

2006

Computers & Fluids

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“…The usability of the current method would be greatly enhanced by additional work on the High-Lift module specifically directed towards modeling wings with powered-lift wings. Some ideas in this area have already been offered by Chattot (58) , and focus primarily on improving the convergence of the solution in cases where the effective angle of attack becomes large.…”

Section: Chapter 8: Conclusion and Recommendationsmentioning

confidence: 99%

A Conceptual Design Methodology for Predicting the Aerodynamics of Upper Surface Blowing on Airfoils and Wings

Keen

2005

23rd AIAA Applied Aerodynamics Conference

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One of the most promising powered-lift concepts is Upper Surface Blowing (USB), where the engines are placed above the wing and the engine exhaust jet becomes attached to the upper surface. The jet thrust can then be vectored by use of the trailing edge curvature since the jet flow tends to remain attached by the "Coanda Effect". Wind tunnel and flight-testing have shown USB aircraft to be capable of producing maximum lift coefficients near 10. They have the additional benefit of shielding the engine noise above the wing and away from the ground.Given the potential gains from USB aircraft, one would expect that conceptual design methods exist for their development. This is not the case however. While relatively complex solutions are available, there is currently no adequate low-fidelity methodology for the conceptual and preliminary design of USB or USB/distributed propulsion aircraft. The focus of the current work is to provide such a methodology for conceptual design of USB aircraft. Based on limited experimental data, the new methodology is shown to compare well with wind tunnel data.In this thesis we have described the new approach, correlated it with available 2-D data, and presented comparisons of our predictions with published USB data and an existing non-linear vortex lattice method. The current approach has been shown to produce good results over a broad range of propulsion system parameters, wing geometries, and flap deflections. In addition, the semi-analytical nature of the methodology will lend itself well to aircraft design programs/optimizers such as ACSYNT. These factors make the current method a useful tool for the design of USB and USB/distributed propulsion aircraft.iii

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Analysis and Design of Wings and Wing/Winglet Combinations at Low Speeds

Cited by 25 publications

References 7 publications

The role of the leading edge vortex in lift augmentation of steadily revolving wings: a change in perspective

The role of the leading edge vortex in lift augmentation of steadily revolving wings: a change in perspective

Helicoidal vortex model for steady and unsteady flows

A Conceptual Design Methodology for Predicting the Aerodynamics of Upper Surface Blowing on Airfoils and Wings

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