External Aerodynamic Flow for High Speed Passenger Car

In recent years, increasing use is being made of computational methods to aid in the understanding of the flow complexities around vehicles and as a result many areas of a car have been studied for numerical solution. Two simulations are made, one for the flow around an Ahmed body and the other of the flow around a simplified high speed passenger car. The former simulation of airflow over Ahmed body is investigated using Fluent in which the configurations included different rear slant angles. The aim of studying such a simplified car body is to understand the flow processes involved in drag production. Through understanding the mechanisms involved in generating drag one should be able to design a car to minimize drag and therefore minimize fuel consumption and maximize performance. Drag coefficients for the Ahmed body predicted by the present computations are compared with the experimental results of Ahmed et al. and found that the maximum drag was obtained for an Ahmed body vehicle with rear slant angle 30° as measured by them. The latter simulation of aerodynamic lift, drag and flow characteristics of a high speed passenger car design configurations were numerically investigated. The predicted drag coefficients are high and it gives positive lift at the rear reducing stability of the car. To keep a sports car stable at high speeds and effectively prevent it from flying off the ground rear spoilers are adopted; here the analysis was carried out with an attached rear spoiler. The results of the passenger car with spoiler showed a reduction of the drag by 10% which results in fuel savings and gives negative lift which increases the car stability and down force.