Improvement of aerodynamic characteristics on vehicle by using vortex generator

Abstract

Aerodynamic forces are generated when air moves relative to the moving vehicle and these forces have a direct effect on vehicle s fuel consumption, stability, driving characteristics, operation and passenger comfort. Vehicle experiences significant drag force when it increases speed above 60 km/hr. The magnitude of surface pressure decreases in the downstream cause the shear layer to separate from the wall. So, the pressure diminishes behind the car and leads to a pressure drag. To overcome the pressure drag, a significant amount of fuel is consumed which reduces fuel efficiency of the car. Hence, it is important to reduce the pressure drag in order to improve the aerodynamic performance of the car. Sports utility vehicle (SUV) and Sedan car models are used extensively in the market however they produce maximum drag force at high speed. The present work focuses to attempt drag reduction through use of Vortex Generator (VG) on above car models. It is proposed to study the aerodynamic drag force reduction of typical SUV (model A) and Sedan (model B) car models mounted with VG for various wind speeds using experimental and computational methods. VG is one of the add-on devices which delays flow separation in flow field so that reattachment of flow occurs and adds energy to flow field in the downstream. Car models geometrically scaled down to 1:12 were fabricated. A subsonic wind tunnel is utilized in this research work and consists of a test cross section of about 1.2 m × 0.9 m. The surface pressure data and drag force on the car models were measured using ESP-64 channel pressure scanner and two component force balance respectively for various wind speeds. The Reynolds numbers are calculated as minimum of 3×105 and maximum of 5.4×105 for the car models used in this study. newline