Airfoil ground effect revisited

Coulliette, C.; Plotkin, Allen

doi:10.2514/6.1995-1832

Cited by 25 publications

(27 citation statements)

References 3 publications

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“…In steady flight, ground effect has been extensively studied (see, for example, Coulliette & Plotkin 1996), and it has inspired the design of a number of aircraft (Rozhdestvensky 2006). Many animals are also known to use ground effect to improve their cost of transport and increase gliding distance, including herring gulls (Baudinette & Schmidt-Nielsen 1974), brown pelicans (Hainsworth 1988), black skimmers (Withers & Timko 1977), mandarin fish (Blake 1979), steelhead trout (Webb 1993), and flying fish (Park & Choi 2010).…”

Section: Introductionmentioning

confidence: 99%

Unsteady propulsion near a solid boundary

et al. 2014

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Experimental and computational results are presented on an aerofoil undergoing pitch oscillations in ground effect, that is, close to a solid boundary. The time-averaged thrust is found to increase monotonically as the mean position of the aerofoil approaches the boundary while the propulsive efficiency stays relatively constant, showing that ground effect can enhance thrust at little extra cost for a pitching aerofoil. Vortices shed into the wake form pairs rather than vortex streets, so that in the mean a momentum jet is formed that angles away from the boundary. The time-averaged lift production is found to have two distinct regimes. When the pitching aerofoil is between 0.4 and 1 chord lengths from the ground, the lift force pulls the aerofoil towards the ground. In contrast, for wall proximities between 0.25 and 0.4 chord lengths, the lift force pushes the aerofoil away from the ground. Between these two regimes there is a stable equilibrium point where the time-averaged lift is zero and thrust is enhanced by approximately 40 %.

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Section: Introductionmentioning

confidence: 99%

Unsteady propulsion near a solid boundary

et al. 2014

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“…While there are benefits as the airfoil approaches the ground, previous research by Coilliette and Plotkin 12 have found that there limiting solutions to the produced Figure 5, including, angle of attack and the camber of the airfoil. The aforementioned research found that for a symmetric Joukowski airfoil at an angle of attack of zero degrees, produced a result inverted from Figure 5.…”

Section: B Ground Effectmentioning

confidence: 97%

Lift Enhancement of Circulation Control as Influenced by Ground Effect

Patterson

Angle

Smith

2011

29th AIAA Applied Aerodynamics Conference

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Circulation control and a lifting surface influenced by ground effect have both individually proven to augment the generation of lift. Recent research at West Virginia University has explored the feasibility of amalgamating the two phenomena, in an attempt to enhance each other. This effort experimentally explores the impact that operation in close proximity to the ground has on a NACA 0018 circulation control modified model in West Virginia University's Closed Loop Wind Tunnel. To simulate the ground, a plane of symmetry methodology was employed by including a second NACA 0018 circulation control modified model as a mirror image to the instrumented model. Since the models have identical geometries, along with the same blowing coefficients, the vertical velocities generated by the two models interact at the center and nullify each other, creating the symmetry plane. While there are many variables that influence the two phenomena separately, this effort only considers the impact the ground and the blowing coefficient has on the aerodynamic quantities. To create this effect, one of the models remains fixed while the other model varies at three designated distances, corresponding to an h/c value of 0.258, 0.646, and 0.984. This research effort demonstrates that with the constraints of zero angle of attack and low blowing coefficients, the combinataion of circulation control and ground effect detract from one another, in terms of L/D, however more research is necessary to explore the aforementioned constraints. Nomenclature A jet= area of the jet T plenum = temperature of the plenum b = wing span u(x) = horizontal velocity contributionlift coefficient out of ground effect γ = specific heat ratio of air C p = coefficient of pressure ΔP = local pressure differential C μ = blowing coefficient ρ j = density of the jet c = chord length ρ ∞ = free stream density H = height at the lowest point of the wing from the ground h/c = height from ground to chord length ratio h(x) = height of the lower surface of the airfoil h te = height of the trailing edge = mass flow rate P plenum = pressure of the plenum P ∞ = free stream pressure P = pressure at location x q,q ∞ = dynamic pressure R = universal gas constant T = thrust of the jet 1 Undergraduate Researcher, Mechanical and Aerospace Engineering, P.O. Box 6070, Student Member 2 Post-Doctoral Fellow, Mechanical and Aerospace Engineering,

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“…Ranzenbach et al also used a two-element airfoil NACA 63 2 -215 Mod B [7]. A good review can be found in the work presented by Coulliette and Plotkin [8]. The parameters studied in this two-dimensional flow approach include the effect of the airfoil thickness, camber, and angle of attack for an airfoil with ground effect.…”

Section: Introductionmentioning

confidence: 96%

Racecar Front Wing Aerodynamics

Mokhtar

Lane

2008

SAE Int. J. Passeng. Cars – Mech. Syst.

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A numerical study of a racecar front wing is presented. The focus of the study is to investigate the aerodynamics characteristics of a wing operating in a small ground clearance. A finite-span wing with a symmetric airfoil section is used. It was found that as the wing gets closer to the ground it generates more downforce and more drag. As the wing gets very close to the ground, the downforce reaches a maximum value and after that the wing generated less downforce as it gets closer to the ground. The drag force follows a similar trend of dependency on the ground clearance. The lower surface of the wing and the ground form a convergent-divergentnozzle shape that is responsible of all the changes in the generated forces. For very small ground clearances, the boundary layers developed on the wing lower surface and the ground get closer to each other, decrease the airflow below the wing and ultimately decrease the generated downforce significantly. The study was preformed using the CFD package STAR CCM+, developed by CD Adapco.

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Airfoil ground effect revisited

Cited by 25 publications

References 3 publications

Unsteady propulsion near a solid boundary

Unsteady propulsion near a solid boundary

Lift Enhancement of Circulation Control as Influenced by Ground Effect

Racecar Front Wing Aerodynamics

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