Flow topology of a container train wagon subjected to varying local loading configurations

Abstract How the positioning and length of a container placed on an arbitrary train wagon in an otherwise fully loaded train affects the local aerodynamics, and consequently the contribution to drag, is examined here. Results from scale-model wind-tunnel tests undertaken at a Reynolds number of 0.3 × 10 6 for a combination of 49 upstream and downstream gap spacings ( G f , G r ) are presented. Surface flow topology, pressure profiles and planar velocity fields are measured. G f dominated the drag variations, with G r only causing a secondary effect. The greatest drag reduction potential is found between gaps size of 1.77 W and 3.23 W , where W represents the wagon width. Over the range of G f and G r investigated, a number of distinct physical mechanisms were observed. These affect the separation size and the nature of boundary layer enveloping the wagon, which have a direct impact on the entrainment and shedding frequency of the wake.

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