Research on Aerodynamic Performance Enhancement of an Automobile Through Utilization of Cooling Ventilation

Feiyi Chen･Takuji Nakashima･Takenori Hiraoka (Hiroshima University)･Keigo Shimizu･Yusuke Nakamura (Mazda)･Hidemi Mutsuda (Hiroshima University)

In this study, the feasibility of aerodynamic performance enhancement of an automobile through utilization of cooling ventilation was investigated. A general vehicle model for aerodynamic research was used as the investigated vehicle, and the shape of the exhaust duct leading to the base surface was parametrically optimized to reduce the aerodynamic drag. As a result, the optimal duct reduced overall drag more than the ideal model without radiator ventilation, although the radiator ventilation volume was reduced by half compared to the original model.

Relationship between the window in the tunnel entrance hood and the flow around the vehicle

Naoto Kato･Moeri Okawa (Graduate School of Utsunomiya University)･Keisuke Yoshida (TOYOTA GAZOO Racing Development Co., Ltd.)･Hiroaki Hasegawa (Graduate School of Utsunomiya University)

Tunnel entrance hoods are installed to reduce micro-pressure waves to the tunnels for high-speed vehicles. In this study, computational fluid dynamics is performed to analyze the structure of the flow around a tunnel entrance hood and a vehicle model. The vehicle model is moved by overset mesh. The flow between the tunnel and the vehicle is visualized and the pressure in the tunnel is measured. CFD results are compared with previously reported experiments to confirm their validity.

Identification of flow fields contributing to aerodynamic drag on an automobile using graph-structured analysis

Yusuke Nakamura･Mitsugu Mera･Keigo Shimizu･Kohei Seo (Mazda)･Takenori Hiraoka･Takuji Nakashima (Hiroshima University)

The identification of flow fields contributing to aerodynamic drag using graph-structured analysis is presented. Unsteady computational fluid dynamics simulation was performed to obtain time-series data of the drag coefficient and the total pressure coefficients at probes placed in space. By analyzing these data with graph-structured analysis, a directed graph representing the causal relationship between the positions of the probes and the drag coefficient was visualized. Based on the result, an attempt was made to identify the flow fields contributing to the drag coefficient.

A study on the reduction mechanism of modulated wind noise by numerical simulation reproducing fluctuation of natural wind

Takumi Hirata (Nissan Motor)･Atsushi Tajima (Kobe University)･Takahiro Kamiwaki (Nissan Motor)･Junichi Wakamatsu (Junichi)･Jun Ikeda･Kousuke Nakasato (Nissan Motor)･Chung-gang Li (RIKEN)･Makoto Tsubokura (Kobe University/Riken)

When a vehicle is driving in real driving environments, frequency modulated wind noise may make passengers uncomfortable. We are trying to clarify the mechanism of the frequency modulated wind noise by large-scale numerical simulation which reproduced the fluctuation of the natural winds using ”FUGAKU". In this paper, the reduction mechanism was studied using the numerical simulation for the item with the reduction effect.

Investigation of required spatial resolution of CFD for predicting separation points around A-Pillar

Kazuaki Hiwatashi･Ryuta Yonemitsu･Masayuki Watarai (Honda Motor)･Kazuya Abiko (Auto Technic Japan)･Jiayi Zhang (PERSOL CROSS TECHNOLOGY)･Tsuyoshi Terakawa (Honda Techno Fort)

In the development of wind noise performance, accurate flow evaluation for the aerodynamic design is necessary.
Currently, this verification is conducted with wind tunnel testing, high-precision CFD predictions are necessary to shorten the development period.
In this presentation, required calculation settings to predict A-pillar separation points are investigated. Additionally, the validity of the settings is confirmed by comparing them with wind tunnel test results.