Search Results

The aerodynamic drag and lift of a sport-motorcycle was investigated in a full-scale and in a 1/6th scale wind tunnel tests. The results show the large vertical load transfer to the rear wheel as vehicle’s speed increases. Consequently, several simple dive and splitter-plates were tested to balance the motorcycle and primarily increase the front axle aerodynamic downforce. These devices were added at a relatively low position on the bodywork in order to avoid adverse handling effects while leaning in turns. This study shows the level of downforce that can be generated by simple add-ons without major alterations to the bodywork. Consequently, for higher levels of aerodynamic downforce, larger underbody surfaces or wings are needed.

A two-seat sports car was designed with the initial marketing goal of breaking the Laguna-Seca racetrack record. This study reports the external aerodynamic modifications that resulted in a significant increase in the vehicle's downforce. The main objective of this study is to report about the method used, which was significantly simpler and much faster than traditional methods used by the automotive industry. Because of the simplicity of the tools used (e.g., computations and wind tunnel), valid engineering conclusions could have been reached only by combining these tools.

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 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.

The aerodynamic characteristics of a sprint car model were tested in a small-scale wind tunnel. Lateral characteristics such as the side force and rolling moment were measured in addition to the vehicle's downforce and drag. Measured data indicated that during the rapid cornering of these race cars, lateral loads are as important as downforce. Since literature search revealed no aerodynamic data on such asymmetric vehicles, a typical baseline sprint car model was tested first with particular focus on large sideslip conditions. Modified wing and side fin geometries were also tested for improved visibility and in search for additional downforce. The experimental data indicate, for example, that a reduced endplate size of the main wing can improve driver visibility without significant loss of aerodynamic downforce.

During a high-speed drag race a race-car nose may accidentally be lifted by the aerodynamic loads causing the dangerous ‘Blow Over’ phenomenon. Such aerodynamic loads were investigated for a wide range of pitch angles in small-scale wind-tunnel tests, using a Top-Fuel Dragster model. A simple device, creating negative vortex lift, was proposed and tested in an effort to reduce the pitch up moments during the initial phases of the ‘Blow Over’. Results of the wind tunnel tests indicate that when deploying the proposed device, immediately after the front wheel liftoff, alleviation of the ‘Blow Over’ is possible.

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.

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).

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.