An Investigation of Train Drag Reduction Using Sub-Boundary Layer Vortex Generators on a Simplified Intermodal Well Car Geometr

Railroad companies in the United States spent about $6.6 billion on diesel to move freight in 2015. One way to save money and reduce fuel consumption is to reduce the drag on the train. With the length of trains in the United States the drag due to the gaps between cars in the train is substantial. To reduce the drag between cars the intermodal well car was investigated. These cars carry intermodal containers often stacked two high. There were 12.2 million intermodal containers shipped in 2015, making the intermodal well car one of the most common cars in use. To avoid the need for major structural changes to the intermodal container wishbone vortex generators were investigated. Using steady Reynolds-Averaged Navier-Stokes simulations the flow field around a train consisting of a scaled and simplified locomotive and two intermodal cars was investigated. Sub-boundary layer vortex generators were then added to this model in two configurations. The first configuration added vortex generators to the rear of the intermodal cars, whereas the second configuration added vortex generators to both the front and rear of the intermodal cars. The vortex generators were sized according to two different boundary layer heights. The first height was found using flat plate turbulent boundary layer theory. The second used the boundary layer developed at the end of the first intermodal car. The addition of the smaller vortex generator showed a 2% drag reduction. While this reduction is close to the minimum accuracy of the simulation, the change in the drag on each car shows that further study is necessary to truly evaluate these devices. The larger vortex generators on the other hand show a 12% increase in the drag of the train.