Cambered airfoil in ground effect - Wind tunnel and road conditions

Abstract

A critical aspect of the performance of the front wing of a Formula One or Indy race car is studied by idealizing it as a negatively cambered two-dimensional airfoil operating in ground effect and computing the flowfield at various heights. When the airfoil operates at heights roughly equal to the airfoil thickness, significant negative lift is generated. As the height is decreased, there is an expected downforce reduction.The primary objective of this work is to elucidate the force reduction phenomena for the specific case of an upside down NACA 4412 airfoil traveling at high Reynolds number above ground in still air by utilizing a Reynolds Averaged Navier Stokes solver. This is the road condition. The secondary objective is to compare and contrast the flowfield about this airfoil in road conditions and when operating in the wind tunnel environment, i.e. when the airfoil and the ground are not moving relative to each other.

An investigation on the aerodynamics of a symmetrical airfoil in ground effect

“…It has now been well documented that running in close to the ground gives increased lift force and studies have been performed both experimentally and numerically [7][8][9][10][11][12][13][14]. Studies performed by Ranzenbach and Barlow [12][13][14] demonstrated the ground effect for a single element airfoil configuration. They performed experiments and did numerical studies on single element symmetrical and cambered airfoils.…”

“…There have been some experimental as well as theoretical studies on influence of different wing configurations on the aerodynamic characteristics [7][8][9][10][11][12][13][14][15][16][17][18][19]. It has now been well documented that running in close to the ground gives increased lift force and studies have been performed both experimentally and numerically [7][8][9][10][11][12][13][14]. Studies performed by Ranzenbach and Barlow [12][13][14] demonstrated the ground effect for a single element airfoil configuration.…”

Influence of wing span on the aerodynamics of wings in ground effect

“…Nor was the true two-dimensionality of flow at the semispan evaluated. Wing span and related endplate effects are important variables when designing wind tunnel experiments to obtain quasi-two-dimensional sectional pressures and forces on highly cambered wings in ground effect, 7 and given that front wing regulations change regularly in open-wheel categories, the influence of span is certainly worth characterizing and under-The series of experiments and simulations conducted by Ranzenbach 8 and Ranzenbach and Barlow 9 in the mid-1990s represented the first systematic public inves tigation of downforce-producing wings in ground effect, and they noted that a wing would continue to increase in drag and downforce as ground clearance reduced. This trend held until very low clearances (for instance, a height-to-chord ratio h/c ¼ 0.097 for a NACA4412 section), at which point the negative lift produced would reach a maximum and then drop off with continued ground proximity.…”

Vortex Induced Aerodynamic Forces on a Flat Plate in Ground Proximity

“…This work demonstrated the effectiveness of such configurations in terms of aerodynamic lift (downforce) generation, but the experimental study was carried out over a fixed ground plane which may have a considerable impact on the flow characteristics at small ground clearances. Numerical studies by Ranzenbach et al [4] on a cambered aerofoil in ground effect showed an appreciable error with downforce increasing and drag in most cases reducing when the ground plane is stationary. Ranzenbach found that lift increases with ground proximity until such a point when the ground and body boundary layers merge thus reducing the underbody flow velocity and giving a lift peak at some finite ground clearance.…”