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Technical Paper

Aerodynamic Effects of Indy Car Components

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.
Technical Paper

Full-Scale, Ort-Road Study of the Effect of Automobile Shape on its Aerodynamic Characteristics, and Comparison with Small-Scale Wind Tunnel Results

The design of passenger vehicles for improved aerodynamic characteristics will result in reduced fuel consumption and better road handling during high-speed driving. In this research, techniques were developed to measure the aerodynamic drag and lift forces acting on a full-scale vehicle under road conditions and then were compared with results obtained on reduced-scale models in a wind tunnel. A number of configurations which characterize common vehicle forms were investigated for their effect on aerodynamic efficiency and fuel consumption, Experimental speeds were between 70 and 110 km/h, these being representative of highway driving conditions. A typical passenger vehicle of the three-box type was selected for the experiments, and its exterior form was altered by means of attaching various configurations to its front, rear, and underbody portions.
Technical Paper

Investigation of Negative Lifting Surfaces Attached to an Open-Wheel Racing Car Configuration

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.
Technical Paper

Effect of Wing/Body Interaction on the Aerodynamics of Two Generic Racing Cars

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).
Technical Paper

Study of an Open-Wheel Racing-Car's Rear-Wing Aerodynamics

The effect of a race-car's rear-wing shape on its high-lift aerodynamic characteristics was investigated numerically and experimentally. These geometrical variations included parameters such as wing leading-edge sweep, several chord-wise elements, addition of trailing edge flaps and of side fins. The main advantage of the numerical computations was to allow for the investigation of a large number of wing geometries without an expensive and lengthy fabrication process of similar wind-tunnel models. Results of this study indicate that complying with the current Championship Auto Racing Teams (CART) regulations, a rear wing with a lift coefficient on the order of −2.2 (based on wing's reference area) is possible.
Technical Paper

Application of Computational Methods to the Aerodynamic Development of a Prototype Race Car

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.
Technical Paper

High Lift Wing Design for Race-Car Applications

The transfer of high-lift wing design methodology from the aerospace industry to race-car application faces certain difficulties due to differences in the operating conditions. Three typical examples are used to demonstrate these different operating conditions; the first of which is the extreme ground effect experienced by the front wings of various open wheel race cars. The following examples focus on the strong interaction between wings and the vehicle's body and on the unique features of certain small-aspect ratio, high-downforce rear wings. Consequently, a well designed airplane airfoil cannot be used automatically on a race car. However, when accounting for these different operating conditions, traditional aeronautical tools can be used to develop an equally successful race car wing. The approach then is to define a desirable target pressure distribution which may be borrowed from airplane applications.