The use of passive ducting from the vehicle nose out of the front wheel opening was studied as a method of modifying the wake profile of NASCAR race vehicle and its effect on drag of a trailing vehicle in various platoon configurations. Utilizing a fixed inlet area due to geometric constraints, exit angle, height and exit/inlet ratio were explored using multi-vehicle Computational Fluid Dynamics (CFD) simulations and wind tunnel validation. Results indicate that appropriately positioned ducts reduce trailing car drag throughout the range of vehicle spacing studied; most significantly, it reduces the drag peak for the trailing car at approximately one car length spacing. Increased exit area is shown to reduce drag for the trailing car, as well as increasing exit angle closer to perpendicular to the direction of travel. Aerodynamic efficiency was increased over baseline with the duct exit angle closer to the direction of travel, while it was negatively impacted with the ducts closer to perpendicular to the direction of travel. Wind tunnel testing confirmed that aerodynamic efficiency improvement was due to an increase in negative lift under the car while Kiel probe measurements validated the shape and positioning of the wake changes caused by the ducts.
展开▼
