Effects of an Air Spoiler on the Wake of a Road Vehicle by PIV Measurements

  • Authors:

  • J. S. Kim;S. Kim;J. Sung;J. Choi

  • Affiliations:

  • Mech. Eng., Grad. Sch., Sunchon Natnl. Univ., 315 Maegok, Suncheon Jeonnam 540-742, Korea and Sch. of Mech. and Aerospace Eng., Coll. of Eng., Sunchon Natnl. Univ., 315 Maegok, Suncheon, Jeonnam 5 ...;School of Mechanical and Aerospace Engineering, College of Engineering, Sunchon National University, 315 Maegok, Suncheon, Jeonnam 540-742, Korea. E-mail: ksc@sunchon.ac.kr;Department of Mechanical Engineering, College of Engineering, Seoul National University of Technology, Seoul 139-743, Korea;School of Mechanical and Aerospace Engineering, College of Engineering, Sunchon National University, 315 Maegok, Suncheon, Jeonnam 540-742, Korea. E-mail: ksc@sunchon.ac.kr

  • Venue:
  • Journal of Visualization
  • Year:
  • 2006

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Abstract

A particle image velocimetry (PIV) technique has been used to analyze the flow characteristics behind a road vehicle with/without an air spoiler attached on its trunk and also to estimate its effect on the wake. A vehicle model scaled in the ratio of 1/43 is set up in the mid-section of a closed-loop water tunnel. The Reynolds number based on the vehicle length is 10$^5$. To investigate the three-dimensional structure of the recirculation zone and vortices, measurements are carried out on the planes both parallel and perpendicular to the free stream, respectively. The results show significantly different vorticity distributions in the recirculation region according to the existence of the air spoiler. The focus and the saddle point, appearing in the wake, are disposed differently along the spanwise direction. Regarding the streamwise vortices, the air spoiler produces large wing tip vortices. They have opposite rotational directions to C-pillar vortices which are commonly observed in the case that an air spoiler is absent. The wing tip vortices generate the down force and as a result, they might make the vehicle more stable in driving.