Computational Study Of Curved Underbody Diffusers

This paper presents new results concerning the aerodynamics of the Ahmed body fitted with a non-flat underbody diffuser. As in previous investigations performed, the angle and the length of the diffuser are the parameters systematically varied within ranges relevant for a hatchback passenger car. Coefficients of lift and drag are compared with the values obtained for the flat underbody diffuser, and the results reveal significant improvements concerning aerodynamic characteristics of body.

Effect of Underbody Diffuser on the Aerodynamic Drag of Vehicles in Convoy

Current study examines the effect on coefficient of drag (Cd) of convoy of two reference car bodies (Ahmed body) by employing underbody diffuser on lead body. CFD analysis of convoy is done using Shear-Stress-Transport model under moving ground conditions. The lead body’s diffuser length is taken as 222m with diffuser angle of 0° (no diffuser), 3°, 5, 7°, 9°, 15°, 20°, 25°and 30° each at inter-vehicular 0.25 and 0.75 body length. Each configuration resulting was analyzed with lead body backlite angle of 25° (pre-critical) and 35° (post-critical) with follow body backlite angle remaining 25°. To understand the flow features developed on Ahmed body due to an underbody diffuser a preliminary CFD analysis is done on an isolated body with 25° and 35° backlite angles by applying each diffuser angle in current study. CFD analyses are conducted after performing two validation analyses from previous studies. The drag on lead and follow vehicles was found to also depend on the axial vortices due to diffuser in addition to those from backlite surface of lead body. Average drag on cases with diffuser is found to be lesser than the no diffuser cases up to a certain diffuser angle. Thus applying diffuser has resulted in potential for reducing the overall drag on convoy by deciding optimum configuration.

Research on Aerodynamic Characteristics of a Simplified SUV Model

The aerodynamics characteristics of square Mira model were researched by simulation, the drag coefficient and the aerodynamic characteristics around model were achieved with analysis of velocity and pressure distribution. Based on results, the angle of rear wind window, the angle of underbody diffuser and the front transition radius were changed, the drag and lift coefficients were achieved. The conclusions provide reference for how to reduce drag coefficient of SUV