Reynolds Equivalent Rolling Road 1/3 Scale Tractor-Trailer Wind Tunnel Model

The future of heavy trucking will require greater aerodynamic improvements and will involve active and automated systems that tailor varied parameters to optimize energy efficiency over a broad operational range. Continuous advancement of accuracy and precision is needed to realize these ever-smaller aerodynamic gains and to generate more detailed aerodynamic characterizations to feed these system-wide optimizations. To accomplish this, a comprehensive aerodynamic development approach is needed and should include computational fluid dynamics, operational testing, and wind tunnel testing. In 2016, a high-fidelity 1/3 scale wind tunnel model of a tractor-trailer heavy truck was developed for Reynolds equivalent wind tunnel testing with full coverage rolling road ground simulation. The model and support system were designed and built for use in the Windshear rolling road wind tunnel. The Windshear wind tunnel offers a large high-speed rolling road system enabling a more advanced simulation of on-road tractor-trailer aerodynamics than has been previously attempted. The system is modular and so allows independent tractor models to be removed from the Windshear-owned trailer section, which houses the primary structure, load measurement, and motion systems. The model drag coefficient repeatability has been measured to be ±0.0007 for individual set points and ±0.00025 for a wind average result. The scale allows for high-fidelity detail while minimizing blockage effects and still enabling high rates of throughput versus full-scale wind tunnel testing. The scale wind tunnel model described here was developed to fulfill the future needs of the industry and be the cornerstone of a modern aerodynamic development approach. The advancement of Reynolds equivalent full ground simulation is an important step in improving aerodynamic development of commercial trucking applications. This article discusses the development of requirements for the model and provides details of the system design and commissioning. Most wind-on results are proprietary in nature, but Reynolds number sensitivity and deflections are shown.