Reducing the aerodynamic drag of empty coal cars

As part of a DOE-sponsored study, the aerodynamic drag of 1/87th-scale coal cars was measured in a wind tunnel. The goal of the experiment was to measure the difference in drag between full and empty cars so as to determine if drag mitigation efforts are warranted. In addition, several simple drag-reduction concepts were studied that were designed to minimize impact on the current coal-car geometry and operation. Covering the coal cars, although impractical, demonstrated that a 42% reduction in drag is possible with no crosswind. Two vertical dividers attached to the existing internal bracing yielded a 23% reduction in wind-averaged drag.