| Résumé | A simulation methodology is introduced to provide improved estimates of the true efficiency gains that can be achieved using aerodynamic drag-reduction technologies for ground vehicles, with a particular application to heavy-duty-vehicle operations. The approach is based on a stochastic simulation methodology that applies route-specific wind conditions to predefined duty cycles, using wind-climate data calculated from publicly-accessible data sets. The simulation tool accounts for vehicle duty-cycle, seasonal wind conditions, the direction of travel, and diurnal effects to generate resultant-velocity and yaw-angle predictions along a specified route. Aerodynamic drag and associated fuel-use predictions are then made based on vehicle aerodynamic performance models generated from sources such as wind-tunnel measurements, road/track measurements, or computational fluid dynamics (CFD) simulations. The simulation software was used to evaluate the benefits of drag-reduction technologies associated with heavy-duty vehicles (HDV) travelling at low speeds on two major routes in Canada. The fuel-savings rate was determined for several drag-reduction technologies and tractor-trailer-height-matching approaches on two highway routes, and at vehicle ground speeds of 50 km/h, 80 km/h, and 100 km/h. This approach provides a representative range of fuel savings that considers the effect of different wind climates on the performance of the drag-reduction strategies. The results suggest that drag-reduction technologies, and particularly height-matching approaches, can have important contributions to reducing fuel use and the associated greenhouse gas emissions at speeds as low as 50 km/h. Vehicle weights ranging from 13,600 kg (30,000 lb) to 54,500 kg (120,000 lb) were evaluated to identify the relative contributions of rolling resistance and aerodynamic drag on a vehicle’s total fuel consumption. Although the proportion of a vehicle’s total fuel consumption from aerodynamics is reduced at low speeds, the fuel savings that can be achieved with standard drag reduction approaches can provide a meaningful reduction in fuel use, a reduction in fuel costs, and a reduction in greenhouse gas emissions. |
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