An empirical correlation between lift and the properties of leading-edge vortices

Jardin, Thierry; Choi, Jeesoon; Colonius, Tim

doi:10.1007/s00162-021-00567-x

Cited by 10 publications

(6 citation statements)

References 37 publications

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“…Cases A and B (with inflow velocity gradients) displayed the greatest force stability, whereas the lift had more significant oscillation in Cases C and D, concomitant with larger oscillation or shedding of the LEV. The lift behavior was found to correspond directly to the LEV strength and proximity effects, in agreement with prior observations 14 .…”

Section: Discussionsupporting

confidence: 90%

“…Pitt Ford and Babinsky 13 demonstrated that, for an impulsively-started translating wing, the LEV contained the majority of the total circulation about the wing. Also looking at impulsively-started translating wings, Jardin et al 14 empirically related the sectional lift coefficient with LEV circulation and the proximity of the LEV to the wing surface.…”

Section: Introductionmentioning

confidence: 99%

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Inflow-velocity and rotational effects on revolving and translating wings

Paulson,

Jardin,

Buchholz

2023

Physics of Fluids

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An aspect ratio 9.5 rectangular wing is articulated in revolving and translating motions at a 45° angle of incidence and Reynolds number Re=O(300). The effects of rotational (Coriolis and centripetal) accelerations and relative inflow velocity profile on vorticity transport within the leading-edge vortex (LEV) system are independently investigated. For the range of displacements studied (180° rotation and corresponding translational displacement), a stably attached leading-edge vortex (LEV) is observed when rotational accelerations and/or a linearly varying inflow velocity profile is present; however, the inflow velocity profile has a stronger effect on stability of the LEV. LEV vorticity magnitude and lift are significantly augmented when both factors are included (i.e., the full revolving wing case). Vorticity transport analyses are conducted in a planar control region two chords from the axis of rotation, where LEV stability is typically observed on revolving wings at high incidence and at an equivalent spanwise position in the translating case. The fully revolving wing case exhibits a substantially larger leading-edge shear-layer vorticity flux than the other cases, whereas Coriolis tilting makes little contribution to regulation of LEV strength. A correlation is found between the spanwise convective flux and tilting flux contributions in all cases. Decomposition of the spanwise convective flux term demonstrates that the two phenomena are kinematically linked and, together, define a new out-of-plane convective flux term that captures the essence of the spanwise convective flux. The role of this term and the effect of rotational accelerations on it are examined.

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Section: Discussionsupporting

confidence: 90%

Section: Introductionmentioning

confidence: 99%

Inflow-velocity and rotational effects on revolving and translating wings

Paulson,

Jardin,

Buchholz

2023

Physics of Fluids

Self Cite

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“…Surface pressure measurements [16] over an AR = 1 rectangular wing show distinct peaks in the pressure distribution adjacent to the wing tips reminiscent of those seen over delta wings-clear evidence of the tip vortices causing a side edge vortex lift contribution. As indicated in the literature [17,18], a lift-generating leading edge vortex can exist over unswept wings subject to unsteady motion. However, as the motion reaches steady state, the lift contribution due to the leading edge vortex rapidly diminishes as the vortical structure convects away from the wing.…”

Section: Introductionmentioning

confidence: 85%

Examination and Prediction of the Lift Components of Low Aspect Ratio Rectangular Flat Plate Wings

Traub

2023

Aerospace

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An investigation of the lift components present over low aspect ratio rectangular wings is presented. Wing aspect ratios ranging from 0.5 to 3 are examined using published experimental results and analytic analysis methods. The methods are based on the fundamental decomposition of Polhamus; that is, lift is attributed to a potential flow lift component coupled with a vortical lift component stemming from the leading and side edges of the flat plate wing. The analysis suggests a low sensitivity to Reynolds numbers spanning three orders of magnitude and brings into doubt the realization of a leading edge vortex lift component for wings with unswept leading edges under steady state conditions. The analytic prediction method of Purvis is shown to provide close accord with all experimental data sets when lift contributions caused by a leading edge vortex are excluded.

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“…Pitt Ford and Babinsky 8 demonstrated that, for an impulsively-started translating wing, the LEV contained the majority of the total circulation about the wing. Also looking at impulsively-started translating wings, Jardin et al 9 empirically related the sectional lift coefficient with LEV circulation and the proximity of the LEV to the wing surface.…”

Section: Introductionmentioning

confidence: 99%

Inflow-Velocity and Rotational Effects on Revolving and Translating Wings

Paulson

Jardin

Buchholz

2023

Preprint

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An aspect ratio 9.5 rectangular wing is articulated in revolving and translating motions at a 45-degree angle of incidence and Reynolds number Re = O(300). The effects of rotational (Coriolis and centripetal) accelerations and relative inflow velocity profile are independently investigated. For the range of displacements studied (180 deg. rotation and corresponding translational displacement) a stably attached leading-edge vortex (LEV) is observed when rotational accelerations and/or a linearly-varying inflow velocity profile is present; however, the inflow velocity profile has a stronger effect on stability of the LEV. LEV vorticity magnitude and lift are significantly augmented when both factors are included (i.e. the full revolving wing case). Vorticity transport analyses are conducted in a planar control region two chords from the axis of rotation, where three-dimensional vorticity transport is shown to be important in mitigating LEV growth, and at an equivalent distance from the wing root in the translating case. The fully revolving wing case exhibits a substantially larger leading-edge shear-layer vorticity flux than the other cases, whereas Coriolis tilting makes little contribution to regulation of LEV strength. A correlation is found between the spanwise convective flux and tilting flux contributions in all cases. Decomposition of the spanwise convective flux term demonstrates that the two phenomena are kinematically linked and yields a significantly simplified vorticity transport equation with a single term consolidating the three-dimensional transport fluxes, thus providing new physical interpretation of vorticity transport in leading-edge vortices.

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An empirical correlation between lift and the properties of leading-edge vortices

Cited by 10 publications

References 37 publications

Inflow-velocity and rotational effects on revolving and translating wings

Inflow-velocity and rotational effects on revolving and translating wings

Examination and Prediction of the Lift Components of Low Aspect Ratio Rectangular Flat Plate Wings

Inflow-Velocity and Rotational Effects on Revolving and Translating Wings

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