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Computational Study of Drag Reduction of Models of Truck-Shaped Bodies in Ground Effect by Active Flow Control
Technical Paper
2013-01-0954
ISSN: 0148-7191, e-ISSN: 2688-3627
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English
Abstract
In U.S., the ground vehicles consume about 77% of all (domestic
and imported) petroleum; 34% is consumed by automobiles, 25% by
light trucks and 18% by large heavy-duty trucks and trailers. It
has been estimated that 1% increase in fuel economy can save 245
million gallons of fuel/year. Furthermore, the fuel consumption by
ground vehicles accounts for over 70% of CO₂ and other greenhouse
gas (GHG) emissions in U.S. Most of the usable energy from the
engine (after accounting for engine losses) at highway speed of 55
mph goes into overcoming the aerodynamic drag (53%) and rolling
resistance (32%); only 9% is required for auxiliary equipment and
6% is used by the drivetrain. 15% reduction in aerodynamic drag at
highway speed of 55 mph can result in about 5-7% in fuel saving.
The goal of this paper is to demonstrate by numerical simulations
on generic truck models that the active flow control (AFC)
technology can be easily deployed/retrofitted to reduce the
aerodynamic drag by 15-20% at highway speed. It is important to
note however that these estimates of drag reduction are based on
CFD studies performed on simple generic truck models; for actual
trucks the values will be much lower because of considerable
complexity of the configurations.
For AFC, we employ a few oscillatory jet actuators (also known
as synthetic jet actuators) at the rear face of the ground vehicle.
These devices are easy to incorporate into the existing vehicles at
very modest cost. The cost may come down significantly for a large
volume of actuators, especially for ground vehicles. Numerical
simulations are performed using the Unsteady Reynolds-Averaged
Navier-Stokes (URANS) equations on solution adaptive structured
grids in conjunction with a two-equation realizable k-ε turbulence
model. The commercially available grid generator "GAMBIT"
and the CFD solver "FLUENT" are employed in the
simulations. Three generic ground vehicle configurations are
considered in the simulations; the experimental data has been
available for these configurations without and with AFC. The
numerical simulations are in good agreement with the experimental
data. In addition, a computational study is performed for one of
the generic truck models to include the ground to evaluate its
effect on aerodynamic drag without and with AFC. These studies
clearly demonstrate that the AFC technique using synthetic jet
actuators can be effectively employed to achieve significant
reduction (10-15%) in aerodynamic drag with a potential of reducing
the fuel consumption by 5-7%.
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Citation
Agarwal, R., "Computational Study of Drag Reduction of Models of Truck-Shaped Bodies in Ground Effect by Active Flow Control," SAE Technical Paper 2013-01-0954, 2013, https://doi.org/10.4271/2013-01-0954.Also In
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