Practical Devices for Heavy Truck Aerodynamic Drag Reduction

This paper presents the impact of a number of practical add-on devices on reducing aerodynamic drag for tractor/semi trailer combination trucks. The evaluations were conducted via reduced scale wind tunnel testing. Sub-scale testing is a very efficient and accurate method to conduct trade studies and evaluate alternate shapes. The test focused on three areas within the tractor-trailer system: tractor-trailer gap, trailer sides and trailer wake. A 23% aerodynamic drag reduction was demonstrated by utilizing trailer skirts, base plates and lengthened side extenders and air fairing. A 20% drag reduction was also demonstrated for several combinations of devices.