Visualized Vortices on Unmanned Combat Air Vehicle Planform: Effect of Reynolds Number

Elkhoury, M.; Rockwell, D.

doi:10.2514/1.6290

Cited by 13 publications

(3 citation statements)

References 4 publications

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“…The Reynolds number dependence of the multiple vortices and their interactions on a generic UCAV configuration was reported by Elkhoury and Rockwell [47] for Re ≤ 40,000. It was shown that the sensitivity of vortex breakdown is much larger at low angles of attack when the vortex system resides closer to the wing.…”

Section: Figures 19a-c Present Computed Solutions Formentioning

confidence: 63%

Unsteady aerodynamics of nonslender delta wings

Gursul

Gordnier

Visbal

2005

Progress in Aerospace Sciences

276

138

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Unsteady aerodynamics of nonslender delta wings, covering topics of shear layer instabilities, structure of nonslender vortices, breakdown, maneuvering wings, and fluid/structure interactions, are reviewed in this paper. Vortical flows develop at very low angles of attack, and form close to the wing surface. This results in strong interactions with the upper-surface boundary layer and in a pronounced dependence of the flow structure on Reynolds number. Vortex breakdown is observed to be much less abrupt compared to breakdown over slender wings. This results in challenges for the precise determination of vortex breakdown location and the interpretation of flow visualizations. One of the distinct features of nonslender wings is the location of the primary attachment zone outboard of the symmetry plane. Reattachment location correlates with the wing stall process and increased buffeting. Dramatic fluid/structure interactions emerge with increasing wing flexibility and result in substantial lift enhancement in the post-stall region. This recently discovered phenomenon appears to be a feature of nonslender wings. Rigid delta wings undergoing small amplitude oscillations in the post-stall region exhibit many similarities to flexible wings, including reattachment and reformation of the leading-edge vortices. Unusual self-excited roll oscillations have also been observed for free-to-roll nonslender wings.

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Section: Figures 19a-c Present Computed Solutions Formentioning

confidence: 63%

Unsteady aerodynamics of nonslender delta wings

Gursul

Gordnier

Visbal

2005

Progress in Aerospace Sciences

276

138

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show abstract

“…The thickness and leading edge geometry of the wing can also affect the flow physics of swept wings but dependence on Reynolds number is not as strong for delta wings with sharp edges. Therefore, aerodynamic forces such as lift and moments do not change substantially with Reynolds number, compared to stronger factors such as incidence and wing sweep [16].…”

Section: Flow Physicsmentioning

confidence: 99%

Flow Control and High-Lift Performance for Flying-Wing Unmanned Combat Air Vehicle Configurations by inserting slots

Ali

Chadwick

2016

IJM

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“…Meanwhile, the maximum lift force coefficient and stall AOA increase accordingly. Elkhoury 5,6) examined the vortex structure of the X-45A at Re ¼ 5 Â 10 3 {1:5 Â 10 4 in static processes and found that different Re generates different vortex structures at the same AOA. Patel 7) executed a wind-tunnel test on the Boeing 1303 UCAV to estimate its performance for AOA ranging from 15 to 35 at Re ¼ 4:12 Â 10 5 .…”

Section: Introductionmentioning

confidence: 99%