Development, Application, and Implementation of Passenger Vehicle Wind Averaged Drag for Vehicle Development

A new methodology is discussed for the development and implementation of a wind-averaged drag analysis technique for the development of aerodynamic-driven surfaces for use in the automotive industry. Current methods of vehicle design focus on reducing the straight-line coefficient of drag using wind tunnel testing and computational fluid dynamics and quote this value as the vehicle's aerodynamic performance. It is suggested to transition passenger vehicle aerodynamic design to the methodology employed for Class-A vehicles and design with a focus on reducing the wind-averaged drag value. Based on the methods used in J1252, the wind averaged drag calculation method utilizes the average wind speed a vehicle will experience in the continental United States and assumes an equal probability of the wind coming from all directions relative to the vehicle. Wind-averaged drag will optimize vehicle design for real-world improvements of vehicle efficiency. The wind average drag developed herein modifies and adapts the current standards for Class-A vehicles and applies it to passenger vehicles. Additionally, this paper includes examples of similarities and differences during the design process of individual parts when designing to reduce the straight-line drag coefficient versus the wind-averaged drag coefficient.