An Investigation of the Different Diffuser Positions Effect on Vehicle Aerodynamic Performance

Abstract

Reducing fuel consumption, increasing road holding and overcoming air resistance are the main goals in the field of vehicle aerodynamics. Therefore, controlling the lifting force and drag force is very important for vehicle stability. Various vehicle parts have been developed to control the airflow in passenger automobiles. One of them is the rear lower diffuser which is located on the floor of the vehicle. In this study, the dimensions of the under body diffuser of a vehicle designed as a 3D model were kept constant and the effects on the lift and drag force at a constant speed of 60 km/h were investigated by positioning the diffuser at 0º, 5º, 10º, 15º, 20º, 25º, and 30ºangles. Analyzes were carried out separately for each diffuser position with CFD analysis in Simcenter Star CMM+ program and the results were examined comparatively according to the flat ground geometry. As a result of the study, it has been seen that the use of diffuser reduces the negative effects by converting the lifting force from positive to negative and provides a significant advantage in drag force compared to the flat ground geometry. The obtained CFD based simulation data provides the basis for optimizing a vehicle diffuser.