Wind tunnel characterization of dynamic wind response

The flow of air moving around and through a vehicle greatly influences its performance and stability. Historically, most of the work in regard to automobile aerodynamics has been focused on the reduction of drag. However, research has been directed in determining the reaction of the side force and yaw moment coefficients to the effects of transient winds. While much work has been done to characterize the mechanical response of automobiles to transient side winds, relatively little has been performed to characterize the effects of these winds on vehicle aerodynamic loading.

In this work, a method of simulating the effect of both speed and direction changes of the relative wind vector was developed. Specifically, modifications were made to the wind tunnel facility at Texas Tech University such that the wind speed could be ramped linearly from 62 to 76 feet per second. In addition, a specially developed turn-table was developed such that a model could be turned in a controlled fashion. The processes of ramping the tunnel velocity and turning the model were controlled and monitored by computer while pressure measurements were made on the model.