Methods on Adjusting Vehicle’s Shape to Control Air Resistance

Abstract

Wind resistance is usually expressed by the following formula. Fx＝ CdAρv^2 /2. Where Cd is a constant. And A is the contact area between air and car. ρ is air density. v is the velocity. Because of the complex structure, mostly a very specific and accurate model cannot be obtained directly. Instead, engineers will use wind tunnel test to get a practical drag coefficient of a car. In the actual analysis, the influence of wind resistance cannot be ignored in the car dynamic system. Wind resistance is the main factor to counteract traction in the process of high-speed driving. Knowledge and literature about aerodynamics of vehicle is abundant in the world. However, this knowledge is not directly related to car design. Engineers empirically design vehicles in the perspective of aerodynamics based on what they have learnt. This paper will put forward some suggestions on vehicle structure according to the practical application of various aerodynamics. It will simultaneously emphasize how the knowledge in the literature is related to the car design in reality. Engineers can design vehicles combining with aerodynamic theory. In recent years, wedge-shaped vehicles have become the mainstream of design, which is the result of the pursuit of low wind resistance and higher stability. The streamlined body shape conforms to both aerodynamics and mainstream aesthetics. Improving speed and safety while saving energy is the most intuitive manifestation of aerodynamic application in vehicle field.