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The flow field over a vehicle and the resulting integral quantities, such as downforce and drag are a direct outcome of the vehicle's shape. During the initial developmental stage, therefore, it would be beneficial to have an inverse capability, dictating vehicle shape, based on a prescribed set of desirable aerodynamic parameters. Although such methods exist for airfoil design, their extension to complex vehicle geometries is far more complicated. Consequently, an alternate approach is experimented with here, whereby a desirable trend in the surface pressure distribution is specified. Using an iterative method, the vehicle shape is modified until the ‘target’ trend in the pressure distribution is met. In the present study such a systematic approach was proposed and used to develop an enclosed wheel racecar shape. During this process of refining the vehicles geometry, computational fluid dynamic tools were used.

A numerical solution based on the Navier-Stokes equation, combined with unstructured grid mesh, was used to model an open wheel race car. The solution is based on a fast, matrix-free, implicit method, with relatively low storage requirements, resulting in solution times up to an order of magnitude smaller than other numerical solutions. The computations provide details on the flow field around the car and a complete pressure distribution on the vehicle's surface. The calculated results may be used as a supplementary tool for wind tunnel or road testing and can provide information, such as the underbody flow, which is difficult to evaluate experimentally. One of the primary advantages of such a viscous flow simulation is the ability to model wheel rotation and to detect regions of flow separation, particularly on the suction side of the front and rear wings.

A generic, Indy-type, open-wheel, racecar model was tested in a low speed, fixed ground wind tunnel. The elevated ground plane method was selected for the road simulation since one of the objectives was to allow flow visualization under the car (and this is not possible with current rolling ground wind tunnel setups). Consequently, both the groundplane and the wind tunnel floor were transparent to facilitate the flow visualization under the vehicle. The aerodynamic loads were measured by a six-component balance, and an effort was made to quantify the partial contributions of the various vehicle components. The main trends and aerodynamic interactions measured with this setup appear to be similar to data measured in larger wind tunnels using rolling ground simulations. As expected, the two wings and the underbody vortex generators generated most of the aerodynamic downforce.

A three-dimensional computer simulation technique was combined with wind-tunnel testing during the aerodynamic development of an enclosed-wheel prototype race car. This approach proved that valuable time can be saved by investigating some of the important design parameters before a vehicle is built. One of the major advantages of a computational approach is that it contains information such as pressure or velocity distribution on and near the whole vehicle. This abundance of data is essential for understanding major design trends and sensitivities, and can steer the design toward fruitful modifications. Once the vehicle's body plan is finalized, the method can be used to further modify local details and to design and position a complicated rear wing cluster. At this phase of wing design, the availability of the pressure distribution on the entire wing surfaces is vital to a successful design.

Aerodynamic lift and drag coefficients of various open-wheel racing car configurations were experimentally investigated. These configurations included several basic fuselage shapes which, in view of the current regulations, did not make use of the “ground effect” to provide negative lift. To these fuselage shapes, which had some positive lift, both unswept wings and delta wings were added to increase their negative lift. The experiments were made with one-tenth scale models, but in order to evaluate these results, comparison is made with full-scale wind tunnel experiments. The results of this work show that useful conclusions can be drawn, based on the small-scale tests, about the relative effectiveness of these aerodynamic devices. Furthermore, with the aid of these lifting surfaces an overall lift coefficient of about minus one was found to be obtainable.

The influence of a rear-mounted wing on the aerodynamics of two generic race car configurations was investigated. Both body-surface pressure and vehicle lift data indicate that the wing/body interaction is large and that, by proper placement of the wing over the body, total downforce coefficients that are considerably larger than the sum of the isolated downforce of the wing and body can be obtained. The above interaction also alters the pressure distribution and spanwise loading on the wing; therefore, the design process for such airfoils should account for the detailed three-dimensional flow field created by the body (contrary to the traditional assumption of placing the wing in an undisturbed free stream).