Aerodynamic drag change of simplified automobile models influenced by a passing vehicle

On-road turbulence caused by atmospheric winds and other automobiles influences the flow field of automobiles and causes variations in aerodynamic forces. Furthermore, the disturbance caused by passing vehicles has a significant impact on drag increase and vehicle stability. Therefore, designing flo...

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Autores principales:	Keigo SHIMIZU, Takuji NAKASHIMA, Takenori HIRAOKA, Yusuke NAKAMURA, Takahide NOUZAWA, Yasuaki DOI
Formato:	article
Lenguaje:	EN
Publicado:	The Japan Society of Mechanical Engineers 2020
Materias:	aerodynamics drag reduction automobile on-road turbulence aerodynamic interaction experimental fluid dynamics (efd) Mechanical engineering and machinery TJ1-1570
Acceso en línea:	https://doaj.org/article/f9cbf5e5dfc64ca089b93878b267389b
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id	oai:doaj.org-article:f9cbf5e5dfc64ca089b93878b267389b
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spelling	oai:doaj.org-article:f9cbf5e5dfc64ca089b93878b267389b2021-11-29T05:52:02ZAerodynamic drag change of simplified automobile models influenced by a passing vehicle2187-974510.1299/mej.19-00366https://doaj.org/article/f9cbf5e5dfc64ca089b93878b267389b2020-02-01T00:00:00Zhttps://www.jstage.jst.go.jp/article/mej/7/1/7_19-00366/_pdf/-char/enhttps://doaj.org/toc/2187-9745On-road turbulence caused by atmospheric winds and other automobiles influences the flow field of automobiles and causes variations in aerodynamic forces. Furthermore, the disturbance caused by passing vehicles has a significant impact on drag increase and vehicle stability. Therefore, designing flow control techniques considering this impact will effectively improve the robustness of automobiles under on-road conditions. In this study, we investigated flow phenomena responsible for drag changes under passing vehicle conditions to reduce drag. Two simplified vehicle models were adopted for the test vehicle. These models are one-fifth scale models, which reproduce the flow structure of production vehicles. The tests were conducted in a wind tunnel that simulated the passing environment where the truck model was placed in the adjacent lane. The drag change and flow characteristics of the truck model were measured by changing the relative positions of the vehicle model and the truck model. The Reynolds number was 1.1×106 at the transition to the turbulent boundary layer in front of the vehicle model. An analysis procedure was proposed to identify the components affecting the drag change using the flow characteristics of a passing vehicle. As a result, three key factors that change drag were identified; variations in the pressure field, crosswind generated by passing vehicles, and the remaining part. Crosswinds are especially important for reducing drag because the contribution of the pressure field to the drag is uniquely determined by the flow characteristics of the passing vehicles and almost zero when the overtaking/being overtaken process is considered. These results provide guidance for designing flow control techniques that are robust against disturbances under on-road conditions.Keigo SHIMIZUTakuji NAKASHIMATakenori HIRAOKAYusuke NAKAMURATakahide NOUZAWAYasuaki DOIThe Japan Society of Mechanical Engineersarticleaerodynamicsdrag reductionautomobileon-road turbulenceaerodynamic interactionexperimental fluid dynamics (efd)Mechanical engineering and machineryTJ1-1570ENMechanical Engineering Journal, Vol 7, Iss 1, Pp 19-00366-19-00366 (2020)
institution	DOAJ
collection	DOAJ
language	EN
topic	aerodynamics drag reduction automobile on-road turbulence aerodynamic interaction experimental fluid dynamics (efd) Mechanical engineering and machinery TJ1-1570
spellingShingle	aerodynamics drag reduction automobile on-road turbulence aerodynamic interaction experimental fluid dynamics (efd) Mechanical engineering and machinery TJ1-1570 Keigo SHIMIZU Takuji NAKASHIMA Takenori HIRAOKA Yusuke NAKAMURA Takahide NOUZAWA Yasuaki DOI Aerodynamic drag change of simplified automobile models influenced by a passing vehicle
description	On-road turbulence caused by atmospheric winds and other automobiles influences the flow field of automobiles and causes variations in aerodynamic forces. Furthermore, the disturbance caused by passing vehicles has a significant impact on drag increase and vehicle stability. Therefore, designing flow control techniques considering this impact will effectively improve the robustness of automobiles under on-road conditions. In this study, we investigated flow phenomena responsible for drag changes under passing vehicle conditions to reduce drag. Two simplified vehicle models were adopted for the test vehicle. These models are one-fifth scale models, which reproduce the flow structure of production vehicles. The tests were conducted in a wind tunnel that simulated the passing environment where the truck model was placed in the adjacent lane. The drag change and flow characteristics of the truck model were measured by changing the relative positions of the vehicle model and the truck model. The Reynolds number was 1.1×106 at the transition to the turbulent boundary layer in front of the vehicle model. An analysis procedure was proposed to identify the components affecting the drag change using the flow characteristics of a passing vehicle. As a result, three key factors that change drag were identified; variations in the pressure field, crosswind generated by passing vehicles, and the remaining part. Crosswinds are especially important for reducing drag because the contribution of the pressure field to the drag is uniquely determined by the flow characteristics of the passing vehicles and almost zero when the overtaking/being overtaken process is considered. These results provide guidance for designing flow control techniques that are robust against disturbances under on-road conditions.
format	article
author	Keigo SHIMIZU Takuji NAKASHIMA Takenori HIRAOKA Yusuke NAKAMURA Takahide NOUZAWA Yasuaki DOI
author_facet	Keigo SHIMIZU Takuji NAKASHIMA Takenori HIRAOKA Yusuke NAKAMURA Takahide NOUZAWA Yasuaki DOI
author_sort	Keigo SHIMIZU
title	Aerodynamic drag change of simplified automobile models influenced by a passing vehicle
title_short	Aerodynamic drag change of simplified automobile models influenced by a passing vehicle
title_full	Aerodynamic drag change of simplified automobile models influenced by a passing vehicle
title_fullStr	Aerodynamic drag change of simplified automobile models influenced by a passing vehicle
title_full_unstemmed	Aerodynamic drag change of simplified automobile models influenced by a passing vehicle
title_sort	aerodynamic drag change of simplified automobile models influenced by a passing vehicle
publisher	The Japan Society of Mechanical Engineers
publishDate	2020
url	https://doaj.org/article/f9cbf5e5dfc64ca089b93878b267389b
work_keys_str_mv	AT keigoshimizu aerodynamicdragchangeofsimplifiedautomobilemodelsinfluencedbyapassingvehicle AT takujinakashima aerodynamicdragchangeofsimplifiedautomobilemodelsinfluencedbyapassingvehicle AT takenorihiraoka aerodynamicdragchangeofsimplifiedautomobilemodelsinfluencedbyapassingvehicle AT yusukenakamura aerodynamicdragchangeofsimplifiedautomobilemodelsinfluencedbyapassingvehicle AT takahidenouzawa aerodynamicdragchangeofsimplifiedautomobilemodelsinfluencedbyapassingvehicle AT yasuakidoi aerodynamicdragchangeofsimplifiedautomobilemodelsinfluencedbyapassingvehicle
_version_	1718407624400044032

Aerodynamic drag change of simplified automobile models influenced by a passing vehicle

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