Numerical simulation of a complete STOVL aircraft in ground effect

Smith, Marnell; Chawla, Kalpana; Dalsem, W. R. Van

doi:10.2514/6.1991-3293

Cited by 25 publications

(6 citation statements)

References 8 publications

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“…Stewart focused on the effects of a moving jet vs a stationary jet in a wind tunnel, whereas Paulson and Kemmerly studied the effects of sink rate on ground vortex formation. Computational efforts include Van Dalsem and Steger, 31 Van Dalsem et al, 32 and Smith et al 33 Navier-Stokes CFD simulations have been obtained for circular and elliptical, laminar and turbulent jets in a crossflow impinging on a ground plane, with generally good agreement with experimentally observed ground vortex location. The recent work of Smith et al presents a simulation of the flow around the complete Harrier AV-8B configuration in ground effect.…”

Section: Nomenclaturementioning

confidence: 73%

Jet ground vortex formation by annular jets

Kuhlman

Cavage

1994

Journal of Aircraft

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An experimental study has been conducted of the impingement of a single circular jet on a ground plane in a crossflow. This geometry is a simplified model of the interaction of propulsive jet exhaust from a V/STOL aircraft with the ground in forward flight. Jets have been oriented normal to the crossflow and ground plane. Jet size, crossflow-to-jet velocity ratio, ground plane-to-jet board spacing, jet exit turbulence level, and mean velocity profile shape have all been varied to determine their effects on the size of the ground vortex interaction region which forms on the ground plane, using smoke injection into the jet. Variation of observed ground vortex size with crossflow-to-jet velocity ratio was consistent with previous studies. Observed effects of jet size and ground plane-to-jet board spacing were relatively small. Jet exit turbulence level effects were also small. However, an annular jet with a low velocity central core was found to have a significantly smaller ground vortex than an equivalent uniform jet at the same values of crossflow-to-jet velocity ratio and jet exit-to-ground plane spacing. This may suggest a means of altering ground vortex behavior somewhat, and points out the importance of proper simulation of jet exit velocity conditions. Laser velocimeter data indicated unsteady turbulence levels in the ground vortex as high as 80%.

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Section: Nomenclaturementioning

confidence: 73%

Jet ground vortex formation by annular jets

Kuhlman

Cavage

1994

Journal of Aircraft

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“…Examples already presented include single and multiple jets in a crossflow. [92][93][94] Additional examples include delta wings with jet nozzles directed towards the ground and a RANS solution 95 for a simplified Harrier (wing, fuselage, inlets, and nozzles). All of these investigators cite two main problems in computing these flows: 1) the need for more accurate solution methods and 2) the need for a faster solution process.…”

Section: Analysis Of a Complete Aircraft The Harriermentioning

confidence: 99%

Jet Induced Effects

Curtis¹,

Kuhn²,

Margason³

2007

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ForewordT HIS TEXT on the most crucial aspect of V/STOL aircraft is co-authored by three experts in this field whose combined experience stretches many decades. The authors have produced a timely volume in view of the development of the F-35B STOVL version of the Joint Strike Fighter and various proposals for V/STOL unmanned aircraft. The volume draws on the authors' vast experience, covering the salient features that affect the flight of V/STOL aircraft during hover and transition to horizontal flight. The authors have identified important technological challenges and have outlined methods that were applied to address them. The text is written in a clear style and it provides methods for estimating the complex aircraft/flowfield interactions through empirical correlations. Thus, the methodology applied is easy to understand and allows the reader to quickly grasp the material. Moreover, the authors share their personal, first-hand insights which are of tremendous value in understanding the complex flows that arise in the V/STOL flight regime.

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“…52 has shown that the standard "k-ε" model over predicts the spreading rate of a free jet and under predicts the spreading rate of a radial wall jet. The most complex (and awesome) study reported so far included all the geometrical and flow details by simulating an entire Harrier aircraft 53,54 , but experimental validation of the ground vortex prediction was not possible since there were no available data. Numerical studies of single impinging jet were selected as the basic configuration to study the V/STOL hot gas ingestion phenomena due to the presence of the ground vortex 55 More recently Ref.…”

Section: Introductionmentioning

confidence: 98%

Multiple Jet/Wall/Cross-Wind Interaction Relevant to VSTOL Ground Effects

Barata

2013

2013 International Powered Lift Conference

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The flowfield of ground vortex and upwash flows generated by single and multiple impinging jets in a crossflow is studied in detail. Laser Doppler measurements and flow visualization are presented for turbulent circular jets emerging into a low-velocity crossstream and, then, impinging on a flat surface perpendicular to the geometrical jet-nozzle axis. The experiments were performed for Reynolds numbers based on the jet-exit conditions of 43,000 to 105,000, a jet-to-crossflow velocity ratio of 30 and for an impinging height of 5 to 20 jet diameters and include mean and turbulent velocity characteristics along the two normal directions parallel to the nozzle axis. The mean velocity, velocity fluctuation and visualization in the impingement region were obtained for velocity ratios between the jet exit and the crossflow V R =V j /U o of 7.5 to 90 with interject spacings of S=5D and L=6D. The largest velocity ratios are characterized by a large penetration of the impinging jets, giving rise to a ground vortex due to the collision of the radial wall jet and the crossflow that wraps around the impinging point like a scarf. The results help to understand the flow around a VSTOL aircraft operating in ground vicinity with front wind or small forward movement that may result in enhanced negative pressures in the underside of the aircraft causing a pitching moment and suction down force towards the ground.

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Numerical simulation of a complete STOVL aircraft in ground effect

Cited by 25 publications

References 8 publications

Jet ground vortex formation by annular jets

Jet ground vortex formation by annular jets

Jet Induced Effects

Multiple Jet/Wall/Cross-Wind Interaction Relevant to VSTOL Ground Effects

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