Drag reduction on aircraft configurations with adaptive lifting surfaces

Cusher, Aaron; Gopalarathnam, Ashok

doi:10.1016/j.ast.2014.01.012

Cited by 12 publications

(4 citation statements)

References 15 publications

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“…For any given flight condition, the lift distributions and aerodynamic forces and moments are computed in the approach by linear superposition of the elementary loadings. The superposition of basic and additional lift distributions is described in several references [25,28,29] and has been used effectively for several decades in wing design [28,30], and most recently in flap optimization of adaptive wings [31,32] and multiple-wing configurations [33]. The results of [31,32] and [33] show that the superposition approach is highly effective in determining the aerodynamics of a lifting-surface configuration with an accuracy comparable with the original analysis method used to compute the elementary lift distributions.…”

Section: Aerodynamic Analysis Methodsmentioning

confidence: 99%

Iteration schemes for rapid post‐stall aerodynamic prediction of wings using a decambering approach

Paul

Gopalarathnam

2014

Numerical Methods in Fluids

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SUMMARYNonlinear aerodynamics of wings may be evaluated using an iterative decambering approach. In this approach, the effect of flow separation due to stall at any wing section is modeled as an effective reduction in section camber. The approach uses a wing analysis method for potential‐flow calculations and viscous airfoil lift curves for the sections as input. The calculation procedure is implemented using a Newton–Raphson iteration to simultaneously satisfy the boundary condition, which comes from potential‐flow wing theory, and drive the sectional operating points toward their respective viscous lift curves, as required for convergence. Of particular interest in this research is the calculation of the residuals during the Newton iteration. Unlike a typical implementation of the Newton iteration, the residual calculation is not performed via a straightforward function evaluation, but rather by estimating the target operating points on the input viscous lift curves. Estimation of these target operating points depends on the assumptions made in the cross‐coupling of the decambering at the different sections. This paper presents four residual calculation schemes for the decambering approach. The residual calculation schemes are compared against each other to assess computational speed and robustness. Decambering results are also compared with higher‐order computational fluid dynamics (CFD) solutions for rectangular and swept wings. Results from the best scheme compare well with the CFD solutions for the rectangular wing, motivating further development of the method. Poor predictions for the swept wings are traced to spanwise propagation of separated flow at stall, highlighting the limitations of the current approach. Copyright © 2014 John Wiley & Sons, Ltd.

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Section: Aerodynamic Analysis Methodsmentioning

confidence: 99%

Iteration schemes for rapid post‐stall aerodynamic prediction of wings using a decambering approach

Paul

Gopalarathnam

2014

Numerical Methods in Fluids

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“…The skin-friction drag contributed the to profile drag in subsonic airliners, and designers typically decrease air pressure in the direction of airflow to maintain laminar flow over wing surfaces and reduce drag. The use of adaptive lifting surfaces like trailing-edge flaps can extend the low-drag range [14].…”

Section: Introductionmentioning

confidence: 99%

Principles and examples of drag reduction in civil airliners

He,

Lu,

Sun

2023

ACE

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Civil aviation has grown rapidly over the past hundred years as demand from air travellers has increased. Since the mid to late 20th century, there have been recurring global energy crises due to political and economic upheavals. In this international context, airlines have tended to operate less draggy, more fuel efficient aircraft in order to maximise profits through fuel cost savings . To this end, aircraft manufacturers have historically tried a variety of methods to address the issue of drag reduction.This paper highlights the importance of three drag reduction methods utilized on modern subsonic airliners by introducing their basic principle and evaluating their effectiveness based on previous research and typical experiments. This paper summarizes and analyzes different approaches to reduce drag in civil aviation. It first investigates the principle behind frictional, induced, and profile drag in theoretical aspects. It then discusses in detail the biomimicry microstructure based on shark skin and its uniqueness on aircraft fuselages surface to reduce frictional drag, the split scimitar winglet and its ideal performance to reduce induced drag when compared with other wingtip devices with different cant angles. The newly introduced adaptive lifting surface changes the wings geometric configuration momentarily, and its ability to reduce profile drag at different stages of flight. This paper also comprehensively compares both the benefits and potential compromises of these drag reduction methods.

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“…The physical premise of the approach is based primarily on the exploitation of changes in induced drag generated by the lift effector. The lift effector will also have an impact on local profile drag, but, for a well implemented design, this will be significantly smaller than the change in induced drag [25]. The problem is posed in the form of allocation of lift based effectors to achieve a given level of yawing moment with zero coupling in pitching moment and rolling moment.…”

Section: Introductionmentioning

confidence: 99%

A Novel Control Allocation Method for Yaw Control of Tailless Aircraft

et al. 2020

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Tailless aircraft without vertical stabilisers typically use drag effectors in the form of spoilers or split flaps to generate control moments in yaw. This paper introduces a novel control allocation method by which full three-axis control authority can be achieved by the use of conventional lift effectors only, which reduces system complexity and control deflection required to achieve a given yawing moment. The proposed method is based on synthesis of control allocation modes that generate asymmetric profile and lift induced drag whilst maintaining the lift, pitching moment and rolling moment at the trim state. The method uses low order models for aerodynamic behaviour characterisation based on thin aerofoil theory, lifting surface methodology and ESDU datasheets and is applied to trapezoidal wings of varying sweep and taper. Control allocation modes are derived using the zero-sets of surrogate models for the characterised aerodynamic behaviours. Results are presented in the form of control allocations for a range of trimmed sideslip angles up to 10 degrees optimised for either maximum aerodynamic efficiency (minimum drag for a specific yawing moment) or minimum aggregate control deflection (as a surrogate observability metric). Outcomes for the two optimisation objectives are correlated in that minimum deflection solutions are always consistent with efficient ones. A configuration with conventional drag effector is used as a reference baseline. It is shown that, through appropriate allocation of lift based control effectors, a given yawing moment can be produced with up to a factor of eight less aggregate control deflection and up to 30% less overall drag compared to use of a conventional drag effector.

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Drag reduction on aircraft configurations with adaptive lifting surfaces

Cited by 12 publications

References 15 publications

Iteration schemes for rapid post‐stall aerodynamic prediction of wings using a decambering approach

Iteration schemes for rapid post‐stall aerodynamic prediction of wings using a decambering approach

Principles and examples of drag reduction in civil airliners

A Novel Control Allocation Method for Yaw Control of Tailless Aircraft

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