Active aerodynamics control of simplified vehicle body in a crosswind condition

• Published in: Journal of engineering (Stevenage, England) Vol. 2020; no. 14; pp. 1005 - 1011
• Main Authors: Nakashima, Takuji, Yan, Chao, Moriuchi, Takashi, Kohri, Itsuhei, Mutsuda, Hidemi, Doi, Yasuaki
• Format: Journal Article
• Language: English
• Published: The Institution of Engineering and Technology 01.11.2020; Wiley
• Subjects: 20th International Conference of Fluid Power and Mechatronic Control Engineering (ICFPMCE 2019); active aerodynamic control method; active aerodynamics control; aerodynamic characteristics; aerodynamic coefficients; aerodynamics; Ahmed model; automobile change; automobiles; bi-stability; bi-stable aerodynamics; computational fluid dynamics; critical yaw angle; crosswind condition; external flows; famous simplified model; flow visualisation; investigated model; jets; model scale; nozzles; relative wind direction; simple vehicle model; simplified vehicle body; slant angle; slit jet; slit nozzle; specific yaw angle range larger than 6; steady jet; vehicle aerodynamic research; vehicle dynamics; wake flow structure changes; wake structures; wakes; wind; wind tunnels; investigated model; aerodynamics; active aerodynamics control; jets; bi-stability; model scale; slit jet; wake structures; critical yaw angle; wake flow structure changes; computational fluid dynamics; automobiles; bi-stable aerodynamics; vehicle dynamics; relative wind direction; famous simplified model; flow visualisation; vehicle aerodynamic research; external flows; automobile change; Ahmed model; crosswind condition; simple vehicle model; active aerodynamic control method; wakes; slit nozzle; specific yaw angle range larger than 6; steady jet; aerodynamic characteristics; aerodynamic coefficients; nozzles; slant angle; wind tunnels; wind; simplified vehicle body
• ISSN: 2051-3305; 2051-3305
• DOI: 10.1049/joe.2020.0062

In this study, the authors used a steady jet from a slit nozzle to control the bi-stable aerodynamics of a simple vehicle model under crosswind conditions. In general, the aerodynamic coefficients of an automobile change continuously with variations in the relative wind direction (i.e. yaw angle). However, some vehicles show a significant change in their aerodynamics at a certain yaw angle because their wake flow structure changes at that yaw angle. Furthermore, around that critical yaw angle, their aerodynamics sometimes show bi-stability in which both the wake structures before and after the change are stable. The investigated model is the famous simplified model in vehicle aerodynamic research known as the Ahmed model. Its slant angle was set at 32° as a configuration that causes bi-stability at a specific yaw angle range larger than 6°. The active aerodynamic control method was demonstrated in both the model scale wind tunnel test and computational fluid dynamics analysis. The slit jet with 18% of the main flow velocity successfully changed the wake flow structure. This showed that it is possible to improve the aerodynamic characteristics.