Aerodynamic Drag Reduction of Railroad Tank Wagons

Several geometrical modifications for passive flow control applied to a railroad tank wagon were investigated for the purpose of assessing the potential for the aerodynamic optimization of freight trains. The modifications were designed in accordance with applicable requirements and regulations. Four different modifications were investigated in the wind tunnel of the TU Berlin with 1:25 scaled wagon models: face radius, side skirts, fairing of the roof platform, and the newly introduced inter-wagon discs. In order to simulate the positions of the tested wagon at the end of a long train, the boundary layer on the train model setup was artificially thickened by spires. The Reynolds number was in the range of 0.4 x 10(6). The results of the experiments show that the proposed measures can reduce the aerodynamic drag of the individual wagon by up to 29%, depending on the location in the train consist. It was also shown that by combining different measures, the individual drag reductions add up. The device with the highest drag reduction was found to be the inter-wagon disc. Three different diameters of the inter-wagon disc were investigated. The largest diameter performed best and was less sensitive to the moving direction of the wagon in comparison to the smaller diameters.