Method for Accelerating the Destruction of Aircraft Wake Vortices

Rennich, Steven C.; Lele, Sanjiva K.

doi:10.2514/2.2444

Cited by 77 publications

(51 citation statements)

References 15 publications

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“…A similar idea was also demonstrated in numerical simulations of Rennich and Lele. 6 Another concept for reducing the intensity of wake vortices is based upon an application for military submarines. The research of Quackenbush et al over the past few years has been directed toward an idea called "vortex leveraging."…”

Section: Introductionmentioning

confidence: 99%

Wake Alleviation Properties of Triangular-Flapped Wings

2002

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The wake alleviation properties of wings with outboard, triangular ap extensions are estimated using data from particle image velocimetry. The experiments are conducted in a towing tank at chord-based Reynolds numbers of O O(10 5 ). The triangular-apped wings generate two unequal strength, counter-rotating vortex pairs that have circulation strength ratios ranging from ¡ 0.4 to ¡ 0.7. Introducing the oppositely signed ap vortices near the tip vortices causes a rapidly growing instability to occur between the vortices on either side of the wake. The resulting nonlinear interactions between the vortices result in a wake that is highly three-dimensional and incoherent. These effects are re ected in a marked decrease in both the rolling moment and downwash on a simulated following wing. To determine the wake alleviation properties of the triangular-apped wings, their wakes are compared to that of a conventional, rectangular wing. For all of the experimental runs, the wakes of the triangular-apped wings have maximum rolling moments and downwashes that are substantially less than those of the rectangular wing. The results indicate that the instability in the wake of the triangular-apped wings offers a possible mechanism to reduce signi cantly the wake hazard problem.

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Section: Introductionmentioning

confidence: 99%

Wake Alleviation Properties of Triangular-Flapped Wings

2002

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“…Management of the counter-rotating inboard vortex is considered important due to its prevalence in many vortex alleviation strategies. 10,13 Figs. 20a-20d show aerodynamic coefficients for the wing which are qualitatively similar to those for the previous case but have two differences: the changes in lift including C L,max are smaller; and low amplitude excitation (C µ ) is effective to higher angles of attack.…”

Section: Outboard Flap Deflection 1 Full-span Flap Controlmentioning

confidence: 99%

“…Time-invariant methods rely on modifying the span loading to establish two or more pairs of opposite-signed counter-rotating vortices and allow naturally arising instabilities to bring about linking and mutual destruction of the vortices. Some examples include appropriately configuring inboard flap vortices, 10 employing multiple differentially deflected flaps 11,12 or employing triangular outboard flaps. 13 Time-dependent methods that actively force the breakup of vortices are realized, for example, by differentially deflecting inboard and outboard control surfaces ("sloshing" of the lift distribution rd figs.…”

Section: A Backgroundmentioning

confidence: 99%

Management of Vortices Trailing Flapped Wings via Separation Control

Greenblatt

2005

43rd AIAA Aerospace Sciences Meeting and Exhibit

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A pilot study was conducted on a flapped semi-span model to investigate the concept and viability of near-wake vortex management via separation control. Passive control was achieved by means of a simple fairing and active control was achieved via zero mass-flux blowing slots. Vortex sheet strength, estimated by integrating surface pressure ports, was used to predict vortex characteristics by means of inviscid rollup relations. Furthermore, vortices trailing the flaps were mapped using a seven-hole probe. Separation control was found to have a marked effect on vortex location, strength, tangential velocity, axial velocity and size over a wide range of angles of attack and control conditions. In general, the vortex trends were well predicted by the inviscid rollup relations. Manipulation of the separated flow near the flap edges exerted significant control over both outboard and inboard edge vortices while producing negligible lift excursions. Dynamic separation and attachment control was found to be an effective means for dynamically perturbing the vortex from arbitrarily long wavelengths down to wavelengths less than a typical wingspan. In summary, separation control has the potential for application to time-independent or time-dependent wake alleviation schemes, where the latter can be deployed to minimize adverse effects on ride-quality and dynamic structural loading. Nomenclature A= wing area, s×c AR = wing aspect ratio c = wing chord-length h = slot width= separation control excitation frequency f w = wake control frequency F + = reduced excitation frequency,

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Section: A Backgroundmentioning

confidence: 99%

Managing Flap Vortices via Separation Control

Greenblatt

2006

AIAA Journal

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A pilot study was conducted on a flapped semi-span model to investigate the concept and viability of near-wake vortex management by means of boundary layer separation control.Passive control was achieved using a simple fairing and active control was achieved via zero mass-flux blowing slots. Vortex sheet strength, estimated by integrating surface pressures, was used to predict vortex characteristics based on inviscid rollup relations and vortices trailing the flaps were mapped using a seven-hole probe. Separation control was found to have a marked effect on vortex location, strength, tangential velocity, axial velocity and size over a wide range of angles of attack and control conditions. In general, the vortex trends were well predicted by the inviscid rollup relations. Manipulation of the separated flow near the flap edges exerted significant control over either outboard or inboard edge vortices while producing small lift and moment excursions. Unsteady surface pressures indicated that dynamic separation and attachment control can be exploited to perturb vortices at wavelengths shorter than a typical wingspan. In summary, separation control has the potential for application to time-independent or time-dependent wake alleviation schemes, where the latter can be deployed to minimize adverse effects on ride-quality and dynamic structural loading.

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Method for Accelerating the Destruction of Aircraft Wake Vortices

Cited by 77 publications

References 15 publications

Wake Alleviation Properties of Triangular-Flapped Wings

Wake Alleviation Properties of Triangular-Flapped Wings

Management of Vortices Trailing Flapped Wings via Separation Control

Managing Flap Vortices via Separation Control

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