Abstract
Nowadays the reduction of drag is becoming a very important challenge for all the car manufacturers as they are competing intensely to produce powerful pickup trucks with better gas mileage in the market regulated with law reinforcement on fuel emissions and consumers’ need for bigger size trucks with more horse power and cargo capacity. Lower drag provides better performances such as higher top speed and better stability. It also often lowers aerodynamic noise and greenhouse gas emission above all decreases in fuel consumption. However, modern designs of pickup trucks tend to go higher and wider and thus they have higher frontal areas due to the functional, economic and aesthetic requirements. Increasing frontal area of the vehicle tend to increase the drag force acting on the vehicle which is proportional to the dimensionless drag coefficient C_D and the projected area of the vehicle. Consequently, to hold or even decrease the drag on a truck that has a larger frontal area, tremendous effort has to be made. The purpose of this research is to design various aerodynamic add-on devices that can be attached to the pickup truck and reduce aerodynamic drag of the vehicle without comprising on its main design features. The research approach is using computational fluid dynamics (CFD) technique. This thesis focuses on investigating the effects of add-on devises such as Tonneau cover, Rear Roof Garnish, Tail plates, Airdam, Traditional canopy, and Aerocap with 5 different rear inclination angles. After the effect of these add-on devise was quantified, Aerocap with rear inclination angle of 12⁰, was identified as the one that had the maximum drag reduction and it was further modified to increase the drag reduction by using the 3D curved Aerocap. The effect that drag reduction had on the fuel economy of the truck was also analyzed. Results from numerical simulations and analyses indicated that the 3D curved Aerocap, modified from the Aerocap with inclination angle α= 12°, had successfully reduced the rear width than the original one. As a result, it had reduced the drag coefficient C_D by about 19.84%. It also reduced the lift coefficient C_(L ) by about 40.72%. At last the impact of 3D curved Aerocap on the fuel economy of the pickup truck was analyzed over the U.S. EPA driving schedules and conclusions were drawn.