A Numerical Optimization Study on Winglets

Khosravi, Shahriar; Zingg, David W.

doi:10.2514/6.2014-2173

“…Applications of CFD-based ASO to wing design have, up until recently, largely focused on the Euler equations [21][22][23][24][25][26][27][28]. Contrary to circulation-distribution and panel methods, the Euler equations do not require the user to prescribe the starting location and shape of the wake.…”

Section: Introductionmentioning

confidence: 98%

Euler-Equation-Based Drag Minimization of Unconventional Aircraft Configurations

Gagnon

¹

,

Zingg

²

2016

Journal of Aircraft

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This study investigates the potential of unconventional aircraft transports through numerical optimization. Three distinct configurations are investigated: a box wing, a C-tip blended wing-body, and a braced wing. Each transport is sized for the same regional mission and is subjected to the same optimization strategy based on the Euler equations. The figure of merit is inviscid pressure drag at transonic speed; the nonlinear constraints are lift, pitching moment, and internal volume. The design variables include the section shape and twist distribution of the main lifting surfaces. It is found that the box-wing, C-tip blended-wing-body, and braced-wing configurations investigated here are, respectively, 34.1, 36.2, and 40.3% more efficient than a similarly optimized conventional tube-and-wing configuration. Each optimization revealed, in one way or another, the importance of accounting for flow nonlinearity during the early stages of unconventional aircraft design. For the blended wing-body, the C tip does not appear to provide a drag benefit over a purely vertical winglet, presumably as a result of the compressibility effects prevalent in the C opening. For the braced wing, compressibility effects also lead to a curious result, where the supporting strut finds itself carrying negative lift at the optimum. Nomenclature= span efficiency L = lift, N n = normal force (section), m q ∞ = freestream dynamic pressure, N∕m 2 W = weight, N x, y, z = chordwise, spanwise, and vertical coordinates, m α = angle of attack, deg

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“…More recently, Whitcomb [8] studied the use of smaller wing extensions attached to the wing tips on transonic aircraft and called them "winglets". Further studies have been carried out [9][10][11][12][13][14][15], in which various methods were used to assess the aerodynamics and the assumed structural impact of adding non-planar span extensions, although with no clear consensus regarding the advantage of a non-planar extension over planar extensions. Assessing the aerodynamics of the different wing options, several methods were used, from fully numerical [9] to purely experimental [8,10].…”

Section: Non-planar Devicesmentioning

confidence: 99%

Conceptual Design and Performance Optimization of a Tip Device for a Regional Turboprop Aircraft

Lappas

¹

,

Ikenaga

²

2019

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An increasing number of aircraft is equipped with wing tip devices, which either are installed by the aircraft manufacturer at the production line or are retrofitted after the delivery of the aircraft to its operator. The installation of wing tip devices has not been a popular choice for regional turboprop aircraft, and the novelty of the current study is to investigate the feasibility of retrofitting the British Aerospace (BAe) Jetstream 31 with an appropriate wing tip device (or winglet) to increase its cruise range performance, taking also into account the aerodynamic and structural impact of the implementation. An aircraft model has been developed, and the simulated optimal winglet design achieved a 2.38% increase of the maximum range by reducing the total drag by 1.19% at a mass penalty of 3.25%, as compared with the baseline aircraft configuration. Other designs were found to be more effective in reducing the total drag, but the structural reinforcement required for their implementation outweighed the achieved performance improvements. Since successful winglet retrofit programs for typical short to medium-range narrow-body aircraft report even more than 3% of block fuel improvements, undertaking the project of installing an optimal winglet design to the BAe Jetstream 31 should also consider a direct operating cost (DOC) assessment on top of the aerodynamic and structural aspects of the retrofit.

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“…Projected span (m) 15 Two extra panels were added to the wing: one transition panel after the wing tip, and a winglet panel. The purpose of using the transition panel was to allow the application of a toe-out angle to the wing-tip base.…”

Section: Parameter (Unit) Valuementioning

confidence: 99%

Conceptual Design and Performance Optimization of a Tip Device for a Regional Turboprop Aircraft.

Lappas¹,

Ikenaga²

2019

Preprint

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An increasing number of aircraft is equipped with wing tip devices, which either are installed by the aircraft manufacturer at the production line or are retrofitted after the delivery of the aircraft to its operator. The installation of wing tip devices has not been a popular choice for regional turboprop aircraft, and the novelty of the current study is to investigate the feasibility of retrofitting the British Aerospace (BAe) Jetstream 31 with an appropriate wing tip device (or winglet) to increase its cruise range performance, taking also into account the aerodynamic and structural impact of the implementation. An aircraft model has been developed, and the simulated optimal winglet design achieved a 2.38% increase of the maximum range by reducing the total drag by 1.19% at a mass penalty of 3.25%, as compared with the baseline aircraft configuration. Other designs were found to be more effective in reducing the total drag, but the structural reinforcement required for their implementation outweighed the achieved performance improvements. Since successful winglet retrofit programs for typical short to medium-range narrow-body aircraft report even more than 3% of block fuel improvements, undertaking the project of installing an optimal winglet design to the BAe Jetstream 31 should also consider a direct operating cost (DOC) assessment on top of the aerodynamic and structural aspects of the retrofit.

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A Numerical Optimization Study on Winglets

Cited by 15 publications

References 29 publications

Euler-Equation-Based Drag Minimization of Unconventional Aircraft Configurations

Euler-Equation-Based Drag Minimization of Unconventional Aircraft Configurations

Conceptual Design and Performance Optimization of a Tip Device for a Regional Turboprop Aircraft

Conceptual Design and Performance Optimization of a Tip Device for a Regional Turboprop Aircraft.

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