Investigation and Development of Underbody Aerodynamic Drag Reduction Devices for Trailer Trucks



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Authors Abstract
It is well known that the underbody region of a tractor-trailer is responsible for up to 30% of the aerodynamic drag. This is the highest drag created by any region of a tractor-trailer. There are a number of underbody drag-reduction devices available on the market but they create a few operational issues, such as low ground clearance and ice collection, which inhibit their mass market appeal. In this paper, a novel concept of an underbody aerodynamic device is developed and investigated. The underbody device is a combination of a ramp and a side skirt; which are optimized simultaneously. In addition, the device is made collapsible to facilitate easy storage when not in use (i.e., city driving). NASA’s Generic Conventional Model (GCM); a 1/8th scale model of a generic class-8 tractor-trailer is used to evaluate and optimize the concept. The GCM allows the concept to be applicable to a wider range of tractor-trailers. The studies were conducted using the RANS based turbulence model, k-ω SST in ANSYS Fluent. The simulations were validated with NASA’s experimental data on the GCM model; which include the surface pressure coefficients and a drag coefficient of the model. The results showed that the underbody device decreased the overall drag coefficient by 4.1%. In addition, the adverse negative pressure region in the wake was significantly reduced.
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Ibrahim, M., and Agelin-chaab, M., "Investigation and Development of Underbody Aerodynamic Drag Reduction Devices for Trailer Trucks," SAE Technical Paper 2018-01-0707, 2018,
Additional Details
Apr 3, 2018
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Technical Paper