Drag Reduction by Application of Different Shape Designs in a Sport Utility Vehicle

Abstract

Road vehicles drag is a direct consequence of a large wake area generated behind. This area is created owing to the vehicle shape, which is determined by the class, functional and aesthetic of the vehicle. Aerodynamic characteristics are a ramification and not the reason for the vehicle architecture. To enhance pressure recovery in the wake region, hence reduce drag, three different passive flow control techniques were applied to sport-utility-vehicle (SUV). A three-dimensional SUV was designed in CATIA, and a numerical flow simulation was conducted using Ansys-Fluent to evaluate the aerodynamic effectiveness of the proposed flow control approaches. A closed rectangular flap as an add-on device modifies the wake vortex system topology, enhances vortex merging, and increases base pressure which leads to a drag reduction of 15.87%. The perforated roof surface layer was used to delay flow separation. The measured base pressure values indicate a higher-pressure recovery, which globally reflected in a drag reduction of 19.82%. Finally, air guided through side rams was used as steady blowing. A steady passive air jet introduced at the core of the longitudinal trailing vortices leads to a confined wake area. The net effects appear in a global increase in the base pressure values and the pronounced drag reduction of 22.67%.