Three Dimensional CFD Analysis on Aerodynamic Drag Reduction of a Bluff Tractor Trailer Body using Vortex Generators

This paper presents a CFD analysis for drag reduction of a Class 8 Tractor-Trailer arrangement. A three dimensional bluff body model of the truck is simulated for a zero degree yaw angle at a speed of 50 miles per hour for a Reynolds Number of 3.3 million. In this paper, the role of vortex generators is investigated for overall drag reduction of the body. The key areas of interest for lowering the drag coefficient are the tractor-trailer gap and the trailer end. The designing of the body was done on DS SolidWorks whereas the CFD simulations were performed on commercial software Ansys Fluent. The Standard k-ε turbulence model was chosen for the simulation while the convergence criterion for the residuals was set at 10⁻⁶. The simple bluff body showed a drag coefficient of 1.654. The first design iteration involved increasing the tractor frontal area which resulted in a reduction of 4% in the drag coefficient. Subsequent iterations involved adding vortex generators to the tractor end which resulted in a drag reduction by 4.63%, the trailer end-tractor end combination which reduces the drag coefficient by 6.16% and the tractor-trailer end and trailer base end which records a reduction in drag coefficient by 8.17%. A further reduction of 9.07% is obtained with the addition of 1 vortex generator each to the sides of the trailer end. It can thus be shown that the vortex generators are an effective yet practical solution to address the issue of aerodynamic efficiency for the current commercial trucks without drastically changing the design layout.