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Scale Effects on the Wake Airflow of a Heavy Truck

Authors: A. Pérard Lecomte, G. Fokoua, A. Mehel, A. Tanière


Automotive experimental measurements in wind tunnel are often conducted on reduced scale. Depending on the study, different similitude parameters are used by researchers to best reproduce the flow at full scale. In this paper, two parameters are investigated, which are Reynolds number and upstream velocity when dealing with airflow of typical urban speed range, below 15 m.s-1. Their impact on flow structures and aerodynamic drag in the wake of a heavy truck model are explored. To achieve this, Computational Fluid Dynamics (CFD) simulations have been conducted with the aim of modeling the wake airflow of full- and reduced-scaled heavy trucks (1/4 and 1/28). The Reynolds Average Navier-Stokes (RANS) approach combined to the Reynolds Stress Model (RSM) as the turbulence model closure was used. Both drag coefficients and upstream velocity profiles (flow topology) were found to be close one another for the three investigated scales, when the dynamical similitude Reynolds is achieved. Moreover, the difference is weak for the simulations based on the same inlet air velocity. Hence, for the relative low velocity range investigated here, the impact of the scale factor is limited.

Keywords: Aerodynamics, CFD, heavy truck, recirculation area, scale effects, similitude parameters.

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[1] B. L. Storms, D. R. Satran, J. T. Heineck and S. M. Walker, "A Study of Reynolds Number Effects and Drag Reduction Concepts on a Generic Tractor-Trailer," NASA Ames Research Center, 2004.
[2] K. R. Cooper and L. Jason, "Model and Full-Scale Wind Tunnel Tests of Second-Generation Aerodynamics Fuel Saving Devices for Tractor-Trailers," SAE Technical Paper, Vols. 2005-01-3512, 2005.
[3] D. Landman, R. Wood, W. Seay and J. Bledsoe, "Understanding Practical Limits of Heavy Truck Drag Reduction," SAE International Journal of Commercial Vehicles, Vols. 2009-01-2890, 2009.
[4] K. H. Lo and K. Kontis, "Flow Characteristics over a Tractor-Trailer Model with and without Vane-Type Vortex Generator Installed," Journal of Wind Engineering and Industrial Aerodynamics, vol. 159, pp. 110-122, 2016.
[5] A. H. Rao, G. Zhang, B. Minelli, Basara and S. Krajnovic, "An LES Investigation of the Near-Wake Flow Topology of a Simplified Heavy Vehicle," Turbulence and Combustion, vol. 102, no. 2, pp. 389-415, 2019.
[6] R. King, "Active Flow Control II," Springer Berlin Heidelberg, p. 417, 2010.
[7] ONISR, "Observatoire des Vitesses," 8 November 2021. (Online). Available: