Use of Designed Experiments in Wind Tunnel Testing of Performance Automobiles

A Design of Experiments (DOE) approach to wind tunnel testing of performance automobiles is being explored at the Langley Full-Scale Tunnel. Traditional methods for wind tunnel testing have focused on conventional “one factor at a time” (OFAT) methods which have difficulty in unearthing valuable interactive effects between variables. In an effort to better characterize a vehicle's aerodynamic behavior as a function of common variables, an exploratory study was completed using the DOE methodology for a common sedan racecar. A two-level factorial designed experiment with center points produced regression models for the lift, drag, and lift to drag ratio as a function of ride height, grille porosity, and yaw angle. In addition, model adequacy and uncertainty levels were described.