Effects of Vortex Generators on Aerodynamic Drag Force in the Hatchback Type Car

Abstract

Aerodynamic drag force is one of the main obstacles on moving a vehicle. This force significantly reduces a vehicle's speed and, as a result, its fuel efficiency. In today’s scenario, fuel efficiency is a prime concern in vehicle design, so a reduction in aerodynamic drag force is highly important. Road vehicles are designed to pass through surrounding air and displace it as efficiently as possible. Due to the rear shape of a car, airflow suddenly separates from the vehicle at a point near the rear windscreen. This flow separation at the rear end of the car is responsible for the drag force, which is the main opposition to the vehicle's forward motion. This drag force is proportional to the square of the velocity of the car and, as a result, increases significantly after certain speeds. To reduce the drag force, the flow separation at the rear end needs to be avoided. In hatch-back type cars, to avoid this separation, a vortex generator (VG) can be used. VG creates the vortex at the rear end of the car, which delays the flow separation and, ultimately, drag is reduced significantly. In this work, the effect of a VG on the pressure distribution, velocity destitution and aerodynamic drag on the hatchback type car, is studied by the numerical simulation. The numerical simulations are carried out using the ANSYS FLUENT® software. The simulation setup is validated with wind tunnel test results.