A preliminary study of configuration effects on the drag of a tractor-trailer combination

The effect of configuration changes and add-on devices on the drag reduction of a tractor-trailer is studied through wind tunnel tests using two 1/12-scale models. The configuration changes involve ground clearance, tractor-trailer gap, roof angle and back inclination while add-on devices include flow deflectors, skirts and gap seals. Moving surface boundary layer control as a means of drag reduction is also attempted. Both drag and pressure data are obtained to help identify local contributions. Results suggest that an optimum combination of configuration parameters can reduce drag up to 17% while the add-on devices resulted in a further decrease by a modest amount. The results with moving surface boundary layer control proved to be inconclusive.Applied Science, Faculty ofMechanical Engineering, Department ofGraduat