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Analysis of Coast-Down Data to Assess Aerodynamic Drag Reduction on Full-Scale Tractor-Trailer Trucks in Windy Environments
ISSN: 0148-7191, e-ISSN: 2688-3627
Published February 01, 1976 by SAE International in United States
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A data reduction procedure is presented and sucessfully used to analyze coast-down data obtained in a windy environment to provide a measure of the aerodynamic drag on a full-scale tractor-trailer combination as a function of the yaw angle of the vehicle. Full-scale drag coefficients were evaluated for a vehicle operated in the baseline mode, and following the addition of four different drag reducing combinations, over a yaw angle range of from -10° to 10°. Comparison with wind tunnel measurements suggests that the wind-tunnel provides a reasonable simulation of the effects of winds on vehicle drag. The full-scale drag reductions measured in the presence of winds were generally lower than those found in wind-tunnel tests, except in situations where a vertical gap seal device was present. In this case, there was good agreement between the results of the coast-down tests and the wind-tunnel tests. The highest drag reductions that were measured in the presence of winds were obtained with a streamlined fairing/gap seal combination, which produced a 32% drag reduction at 0° yaw, and a 21% reduction in wind-averaged drag. The drag reductions obtained with the roof fairing, with and without gap seals, significantly exceeded those obtained with a commercially available wind deflector, with and without a vortex stabilizing device.
CitationBuckley, F., Marks, C., and Walston, W., "Analysis of Coast-Down Data to Assess Aerodynamic Drag Reduction on Full-Scale Tractor-Trailer Trucks in Windy Environments," SAE Technical Paper 760850, 1976, https://doi.org/10.4271/760850.
- Buckley F. T., Jr. Sekscienski W. S. “Comparison of Effectiveness of Commercially Available Devices for the Reduction of Aerodynamic Drag on Tractor-Trailers” SAE Paper No. 750704 August 1975
- Sherlock R. H. “Variations of Wind Velocity and Gusts with Height” Transactions American Society of Civil Engineers 118 463 508 1953
- Taylor G. I. “Eddy Motion in the Atmosphere” Philosophical Transactions of the Royal Society CCXV 1 26 1915
- Marks C.H. Buckley F. T., Jr. Walston W. H., Jr. “An Evaluation of the Aerodynamic Drag Reductions Produced by Various Cab Roof Fairings and a Gap Seal on Tractor-Trailer Trucks” SAE Paper No. 760105 February 1976
- Walston W. H., Jr. Buckley F. T., Jr. Marks C. H. “Test Procedures for the Evaluation of Aerodynamic Drag on Full-Scale Vehicles in Windy Environments” SAE Paper No. 760106 February 1976
- Smith G. L. “Discussion of Truck Drag Components by Road Test Measurement” SAE Transactions 73 157 1965
- Montoya L. C. Steers L. L. “Aerodynamic Drag Reduction Tests on a Full-Scale Tractor-Trailer Combination with Several Add-On Devices” December 1974
- Knight R. E. Radial Truck Tire Engineering Goodyear Tire and Rubber Co. Akron, Ohio