Abstract
Drag and lift are two important parameters to evaluate the aerodynamic performance of a passenger vehicle. Lesser drag and lesser lift (greater downward force) is required for satisfactory performance of a car. The addition of spoiler at rear part of car is used to achieve the requirements. Lip-type spoiler is frequently used for small car. A small car with lip-type spoiler at different directions is investigated computationally. Computational fluid dynamics is applied to obtain drag and lift. Decreasing trend of drag is found with increase in spoiler angle, while lesser lift is found at small spoiler angle and further increase in lift is found with increase in spoiler angle. However the lift at greater spoiler angle is less than the lift of base car (car without spoiler). A compromise of drag and lift is required to achieve satisfactory performance of car in term of power requirement and fuel economy (due to drag force) as well as stability of the car (due to lift). The spoiler angle 60-100 is found optimal one to use benefits of both reduced drag and lift.