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[资源] A Reassessment of Heavy Duty Truck Aerodynamic Design Features and Priorities

Between 1973 and 1982, the NASA Dryden Flight Research Center conducted “coast-down” tests
demonstrating means for reducing the drag of trucks, buses, and motor homes. Numerous configurations
were evaluated using a box-shaped test van, a two-axle truck, and a tractor-semitrailer combination.
Results from three configurations of the test van are of interest now in view of a trucking industry goal of
a 0.25 drag coefficient for tractor-semitrailer combinations. Two test van configurations with blunt-base
geometry, similar to present day trucks (one configuration has square front corners and the other has
rounded front corners), quantify the base drag increase associated with reduced forebody drag. Hoerner’s
equations predict this trend; however, test van results, reinforced by large-scale air vehicle data, indicate
that Hoerner’s formula greatly underestimates this dependence of base drag on forebody efficiency. The
demonstrated increase in base drag associated with forebody refinement indicates that the goal of a
0.25 drag coefficient will not be achieved without also reducing afterbody drag. A third configuration of
the test van had a truncated boattail to reduce afterbody drag and achieved a drag coefficient of 0.242.
These results are included here and references are identified for other means of reducing afterbody drag.

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附件 1 : A_Reassessment_of_Heavy-Duty_Truck_Aerodynamic_Design_Features_and_Priorities.pdf

2015-07-27 23:57:43, 3.35 M