Experimental investigation of a two-truck platoon considering inter-vehicle distance, lateral offset and yaw. Issue 213 (June 2021) - Törnell, Johannes
Abstract: In recent years a renewed interest in platooning has emerged due to increasing pressure on vehicle manufacturers to reduce greenhouse gas emissions of their fleets. Vehicles traveling in close proximity have been studied in some depth, particularly simplified bodies and North American trucks. Still, there is a lack of understanding of the benefits of platooning for European style trucks. In this study, experiments were undertaken using two 1:6 scale detailed cab over engine tractor-trailer models in a wind tunnel with a moving ground. Surface pressures were measured on both trucks, while force measurements were taken on the model placed on the belt. Inter-vehicle distance, lateral offset, and yaw conditions were varied. Results show that a reduction of drag for the platoon is seen as the inter-vehicle distance decreases. For the leading truck, the reduction is due to an increased base pressure caused by the truck behind. The trailing truck has a more complex behavior and is sensitive to yaw changes. At short inter-vehicle distances, the leading truck loses in performance with a lateral offset, while the trailing truck gains in performance if under yaw conditions. To aid the flow analysis, numerical simulations were undertaken for some conditions studied experimentally. Highlights: The combined drag of the platoon improves as the inter-vehicle distance decreases. The drag of leading truck is dominated by the pressure at its trailer base. The drag of the trailing truck has a complex behaviour and great sensitivity to yaw. A lateral offset negatively impacts the drag of the leading truck at short distances. At yaw conditions, the system is sensitive to a change in Reynolds numbers.