Study of the aerodynamics of a full-scale tractor-trailer

The wind tunnel campaign evaluated 10 configurations of a tractor-trailer combination using a Volvo VNL860 tractor and the 30 ft NRC trailer. The test results include balance measurements of drag force, side force, and yawing moment. The baseline tractor-trailer combination had a blockage-corrected drag coefficient of 0.457 at 0° yaw and a wind-averaged drag coefficient of 0.527. The combined removal of the side extenders, their extensions, and the roof air deflector (in Configurations 6 and 7) resulted in the largest increase in drag (6 % relative to baseline) of all of the aerodynamic packages that were evaluated. The smallest change in drag coefficient resulted from the removal of the tractor skirt extensions (aerodynamic package 4), but it should be noted that the tractor skirt extensions were only evaluated at 0 yaw and would have more of an effect at higher yaw angles. The purpose of this paper is to study the drag coefficient of the entire Tractor through wind tunnel experiments. At present, there are few tests on the resistance coefficient of Tractors, and there are also few published papers on this topic. By removing Aerodynamic packages, this helps to understand the impact of different Aerodynamic packages on the overall drag coefficient of the vehicle.