DOE Project on Heavy Vehicle Aerodynamic Drag

Abstract

ObjectiveClass 8 tractor-trailers consume 11-12% of the total US petroleum use. 1 At high way speeds, 65% of the energy expenditure for a Class 8 truck is in overcoming aerodynamic drag. The project objective is to improve fuel economy of Class 8 tractor-trailers by providing guidance on methods of reducing drag by at least 25%. A 25% reduction in drag would present a 12% improvement in fuel economy at highway speeds, equivalent to about 130 midsize tanker ships per year. Specific goals include:• Provide guidance to industry in the reduction of aerodynamic drag of heavy truck vehicles.• Develop innovative drag reducing concepts that are operationally and economically sound.• Establish a database of experimental, computational, and conceptual design information, and demonstrate the potential of new drag-reduction devices. Approach• Develop and demonstrate the ability to simulate and analyze aerodynamic flow around heavy truck vehicles using existing and advanced computational fluid dynamics (CFD) tools.• Through an extensive experimental effort, generate an experimental data base for code validation and for understanding of key drag producing flow characteristics • Provide industry with design guidance and insight into flow phenomena from experiments and computations.• Investigate aero devices (e.g., base flaps, tractor-trailer gap stabilizer, underbody skirts and wedges, blowing and acoustic devices), provide industry with conceptual designs of drag reducing devices, and demonstrate the full-scale fuel economy potential of these devices. Accomplishments• Organized and lead a very successful annual DOE Heavy Vehicle Working Group Meeting with active industry participation. The objective of these annual meetings is to provide a forum for reviewing industry needs, presenting new drag reduction concepts, discussing project direction, and identifying areas of collaboration between industry and DOE supported R&D participants from National Labs, universities and other research organizations. • New flow conditioning concept of "bleeding-flow" device has been shown computationally to provide significant gap flow and trailer base drag reduction. Plans are to perform reduced-scale tests at NASA and full-scale tests at NRC • Providing a consistent, realistic, comprehensive assessment of the energy balance when evaluating devices like with the "bleeding flow" device is needed. Consider and report: o energy used by active features o weight of all components o Impact of design on fleet operation in terms of dollars saved per ton hauled in addition to changes in drag coefficient or fuel use rate. o Yaw-averaged drag values when evaluating design changes.• Tractor and trailer underbody experiments at NASA show small improvement in tractor drag with the use of tractor belly pans or with the covering of cross ribs under the trailer. Experiments also showed that trailer side skirts are still the most promising drag reduction approach.• Evaluation of the impact of small changes in radiator or grille dimensions has revealed that the ...

Experimental and numerical characterization of the airflow in the wake of a heavy truck

“…The literature on heavy trucks aerodynamics 27,[33][34][35][36][37]41 shows that airflow characteristics, including drag, turbulence, and pressure distribution, are highly dependent on the shape, size, and surface characteristics of the truck. The time-averaged drag coefficient returned by the two numerical models is, respectively, 0.578 6 0.002 and 0.605 6 0.002 for the SST k À x and BSL-RSM models.…”

“…Compared to the GTS model, the GCM includes a tractor part and a trailer part separated by a space in between and other components, such as wheels and axles in the sub-trailer. The GCM has been considered in a number of aerodynamic studies, 27,[33][34][35][36] where the focus was mostly on drag-reduction solutions for fuel economy purposes and a few on the flow topology around the heavy truck model. 35 Additional realistic tractor-trailer geometries, slightly different from the GCM, were also considered.…”

“…The GCM has been considered in a number of aerodynamic studies, 27,[33][34][35][36] where the focus was mostly on drag-reduction solutions for fuel economy purposes and a few on the flow topology around the heavy truck model. 35 Additional realistic tractor-trailer geometries, slightly different from the GCM, were also considered. 13,[37][38][39][40][41][42] The recirculation regions obtained for these realistic heavy ground vehicle variants differ slightly from the airflow observed in the GTS model.…”

Aerodynamic Analysis on the Effects of Frontal Deflector on a Truck by using Ansys Software

“…In this analysis, the model used is a generic conventional model (GCM) truck built on the geometry of modern current truck generation [17], [18]. Using SOLIDWORKS software, this model is designed by referring to the modern current truck generation.…”

Computer Modeling and Analysis of Truck Generated Salt-Spray Transport Near Bridges

“…The CFD analysis is focused on salt sprays from vehicle traffic using large trucks as the vehicles most likely to produce significant salt spray plumes to further investigate the geometric parameters defining the so-called "tunnel effects". (McCallen, et al, 2007) covers both CFD analysis and experimental tests with references. This effort and many others demonstrated that CFD is a useful engineering tool that can be applied to the study of the aerodynamics of vehicles.…”