Multi-element airfoil in ground effect - An experimental and computational study

Ranzenbach, Robert; Barlow, Jewel B.; Diaz, Ricardo

doi:10.2514/6.1997-2238

Cited by 30 publications

(21 citation statements)

References 6 publications

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“…Smith 7 described the ve bene cial effects of the gaps between the elements in multielement ows: slat effect, circulation effect, dumping effect, off-the-surface pressure recovery, and fresh-boundary-layer effect. Ranzenbach et al 8 demonstrated the ground effect for a double-element airfoil con guration. Their work begins to address the topic, using twodimensional model tests in a xed ground wind tunnel on a NACA 63 2 ¡215 Mod B section with a 30% slotted ap for the doubleelement studies.…”

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confidence: 99%

Aerodynamics of a double element wing in ground effect

Zhang

Zerihan²

2002

40th AIAA Aerospace Sciences Meeting &Amp; Exhibit

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An investigation of a cambered, double-element, high-lift wing operating in ground effect was performed. The effect of ground proximity and ap setting was quanti ed in terms of aerodynamic performance and off-surface ow eld characteristics. From that, it was found that the ow is three-dimensional toward the wing tip with the main element generating most of the downforce but retains quasi-two-dimensional features near the center of the wing. However, at large heights the downforce increases asymptotically with a reduction in height. Then there is either a plateau, in the case of a low ap angle, or a reduction in downforce, in the case of a large ap angle. The downforce then increases again until it reaches a maximum and then reduces with decreasing height above the ground. The maximum downforce is dictated by gains in downforce from lower surface suction increases and losses in downforce caused by upper surface pressure and lower surface suction losses, with a reduction in height. For the high ap angle there is a sharp reduction just beyond the maximum, mainly because of the boundary layer separating, and a resultant loss of circulation on the main element.

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confidence: 99%

Aerodynamics of a double element wing in ground effect

Zhang

Zerihan²

2002

40th AIAA Aerospace Sciences Meeting &Amp; Exhibit

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“…If the true solution falls within the uncertainty range of the computed solution from a given mesh, the mesh is suitable for use in further simulations. 4 American Institute of Aeronautics and Astronautics …”

Section: Grid Convergence Studymentioning

confidence: 99%

Wake Deceleration of a Racecar Multielement Airfoil in Ground Effect

Bansal

Selig

2016

34th AIAA Applied Aerodynamics Conference

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The importance of aerodynamic downforce in competitive motorsports has been well established. Much of this aerodynamic downforce is produced from the inverted multielement wings at the front and the rear of the car. While such a high-lift system is capable of producing high downforce as a result of the interaction between flows around adjacent elements, there may exist off-the-surface flow reversal, commonly known as wake bursting, causing an adverse effect on the downforce generated. Since the phenomenon of off-the-surface flow reversal occurs as a result of retardation of a wake under adverse pressure gradients, wake bursting is also referred to as wake deceleration in this study. A steady-state two-dimensional CFD analysis of a racecar multielement airfoil was carried out to study wake deceleration characteristics in ground effect. Simulations were performed using ANSYS Fluent TM , which is a finite-volume method (FVM) based commercial hybridgrid Reynolds-averaged Navier-Stokes (RANS) equations solver. Computational results were obtained using a two equation shear stress transport (SST) k-ω model coupled with a one equation intermittency transition model to predict the laminar-to-turbulent boundary layer transition. Effects of ground clearance height on the main element decelerated wake were analyzed. Effects of varying flap ratio, flap deflection, angle of attack, and gap sizes on the wake deceleration patterns have been investigated. It was found that decreasing the ground clearance led to a significant increase in the amount of the main element wake bursting. Increased wake bursting at higher angles of attack was found to have caused a drop in downforce without any surface-flow separation. Although the main element wake was strongly affected while varying each of these parameters, the size of the flap wake was not affected significantly. Nomenclature c = system chord length c 1 = main element chord length c 2 = flap chord length C d = two-dimensional drag coefficient C l = two-dimensional downforce coefficient h = ground clearance height l s,x = overhang distance l s,y = gap size M ∞ = freestream Mach number N = total number of cells in the grid p ∞ = freestream static pressure Re = Reynolds number based on system chord length Re θ = transition momentum thickness Reynolds number T ∞ = freestream static temperature u = velocity component in x-direction v = velocity component in y-direction α = angle of attack δ f = flap deflection angle γ = intermittency ρ = density of air

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“…At a critical ground clearance the pressure recovery is high and boundary-layer separation occurs near the trailing edge of the suction surface, even at α = 0˚. Another important delineation being when there is no force reduction the aerofoil and ground boundary-layers do not merge (8) . Another important delineation being when there is no force reduction the aerofoil and ground boundary-layers do not merge (8) .…”

Section: Introductionmentioning

confidence: 99%

“…Data exist for inverted NACA aerofoil sections in ground effect (6,7,8) but the camber for these sections is usually lower than specially designed aerofoil sections for ground effect, such as the Tyrrell026 aerofoil. With the suction side towards the ground an aerofoil generates substantial negative lift (downforce) as well as an increase in drag.…”

Section: Introductionmentioning

confidence: 99%

“…With the suction side towards the ground an aerofoil generates substantial negative lift (downforce) as well as an increase in drag. This height is dependent on how much lift force the aerofoil generates (8) and the higher the lift coefficient 'C L ' of the aerofoil the higher the ground clearance at which the force reduction occurs. In recent years the Tyrrell026 profile has been studied and data for lift, drag and some limited information on the wake flow field is available (9,10,11) .…”

Section: Introductionmentioning

confidence: 99%

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Aerofoil flow separation suppression using dimples

Beves¹,

Barber

2011

Aeronaut. j.

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Flow separation is a source of aerodynamic inefficiency, by using vortex generators flow separation can be controlled. This is of particular benefit to flows around bodies which are susceptible to separated flows, such as bodies in ground effect. Previous studies on the ability of dimples to produce vortices for flow mixing concerned heat transfer applications. Experimental measurements using Laser Doppler Anemometry (LDA) were taken in the wake of the Tyrrell026 aerofoil (Rec= 0·5 × 105) with a dimple array machined in the surface. Results for a dimple array of three rows placed forward ofx/c= 0·23 with 1·5Ddimple to dimple spacing, showed significant flow recovery in the wake. The velocity deficit ofu/Uo,min= −0·1 recovered tou/Uo,min = 0·3 with the dimple array and the size of the wake reduced by 50%; at α = 10°,h/c= 0·313. The positive effect of the dimple array on the wing reduced as the wing was brought closer to the ground.

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Multi-element airfoil in ground effect - An experimental and computational study

Cited by 30 publications

References 6 publications

Aerodynamics of a double element wing in ground effect

Aerodynamics of a double element wing in ground effect

Wake Deceleration of a Racecar Multielement Airfoil in Ground Effect

Aerofoil flow separation suppression using dimples

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