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The Effect of Base Bleed and Rear Cavities on the Drag of an SUV
Technical Paper
2010-01-0512
ISSN: 0148-7191, e-ISSN: 2688-3627
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English
Abstract
Two methods of passive flow control were investigated to
determine their effectiveness in reducing aerodynamic drag on large
Sports Utility Vehicles (SUVs). Passive means of flow control were
selected since all active methods require the input of additional
energy (e.g., pressurized fluids or electrical energy). The
selected methods were base bleed and the use of a rear cavity, and
various combinations of these were experimentally tested in
full-scale wind tunnels with and without a moving belt/rotating
wheel assembly. Aerodynamic drag reduction was accomplished by
restructuring the low-pressure wake directly behind the
vehicle.
External cavity depths ranging from d/h=0.17 to 0.83 were used,
while body cavity depths ranged from d/h=0 to 0.83, where the depth
of the cavity d is non-dimensionalized by the height h of the base
area. External cavities always resulted in an increase in the drag
coefficient, while for body cavities the reduction in drag improved
with increasing cavity depth. A maximum drag reduction of -3.3% was
achieved.
The base bleed coefficient was varied from Cq=(3-21)
x 10-⁴, and various bleed outlet locations in the base area were
considered. Bleeding air around the periphery of the base area was
found to be the most effective implementation, and depending on the
outlet location the drag reduction ranged from -0.3% to -1.1%.
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Citation
Irving Brown, Y., Windsor, S., and Gaylard, A., "The Effect of Base Bleed and Rear Cavities on the Drag of an SUV," SAE Technical Paper 2010-01-0512, 2010, https://doi.org/10.4271/2010-01-0512.Also In
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