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%.