著者

岡田 義浩 農沢 隆秀 坪倉 誠 中島 卓司

出版者

一般社団法人 日本機械学会

雑誌

日本機械学会論文集 (ISSN:21879761)

巻号頁・発行日

vol.80, no.809, pp.FE0009, 2014 (Released:2014-01-25)

参考文献数

14

被引用文献数

1 2

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In order to clarify unsteady flow structure’s behavior that improves vehicle’s high-speed stability during steering input, on-road analysis was conducted. The analysis was conducted on two vehicles’ aerodynamic specifications which were produced by configuring two different shapes from a single vehicle. During high speed driving while steering input in sinusoidal waveform was being applied, these two vehicles were analyzed focusing on the relationships between dynamic movements, unsteady forces affecting on vehicle’s body surface and unsteady behavior of flow structure. As a result, it was clarified that there existed a unsteady behavior of flow structure that aerodynamically control to stabilize vehicle’s steering response motion in vertical and yawing direction. It was also clarified that this aerodynamic force that control to stabilize vehicle’s steering response motion was caused by behaviors of flow structure beside body just behind front tire which reduced and expand its vertical scale during high-speed driving with steering input. Furthermore, it was shown that this behavior of flow structure was caused by weakening vortex structure which came out and separated from the gap between the upper rear side of the front wheel and the front wheel arch.

著者

中島 卓司 坪倉 誠 岡田 義浩 農沢 隆秀 溝兼 通矢 土井 康明

出版者

一般社団法人 日本機械学会

雑誌

日本機械学会論文集 (ISSN:21879761)

巻号頁・発行日

vol.80, no.818, pp.FE0301-FE0301, 2014 (Released:2014-10-25)

参考文献数

13

被引用文献数

2

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The objective of this study is to investigate aerodynamics and its generating mechanism of a road vehicle in steady-state cornering, which is the most basic cornering condition. The vehicle motion in the steady-state cornering was defined on a frame of reference fixed on the vehicle and it was divided into a rotation around a vertical axis and a sideslip. Then, aerodynamic force generated by each motion and its generating mechanism was discussed. In order to reproduce an effect of the rotational motion, a towing tank experiment was conducted to measure the fluid-dynamic force acting on a one-fifth-scale model of a sedan-type road vehicle. Assuming that the fluid-dynamic forces are expressible as a linear superposition of effects of the rotation and sideslip, first derivatives of the side force and yaw moment with respect to the yaw rate and the lateral velocity were analyzed by a multiple linear regression analysis. From the results of measurement and analysis, it was clarified that the assumption can provide good approximations of the force and the moment within a range of measurement conditions in this study. Regarding the fluid-dynamic side force, the rotation generates a centripetal force of the circular motion and the sideslip generates a force suppressing the slip motion. Regarding the fluid-dynamic yaw moment, the rotation generates a moment suppressing the rotation, and the sideslip generates a moment enhancing the vehicle's slip angle. Aerodynamics of a sedan-type road vehicle was estimated quasi-steadily by multiple regression equations with measured vehicle motion in an on-road test. From this estimation, the effects of both the rotation and the sideslip had the same order of magnitude. This result indicates that the effects of the vehicle's rotational motion have the same level of importance as the effects of the sideslip in vehicle aerodynamics in steady-state cornering.