PIV Measurements on the Change of the Three-Dimensional Wake Structures by an Air Spoiler of a Road Vehicle

  • Authors:

  • J. S. Kim;J. Sung;S. Kim

  • Affiliations:

  • Mech. Eng., Grad. Sch., Sunchon Natnl. Univ., 315 Maegok-dong, Suncheon, Jeonnam 540-742, Korea and School of Mech. and Aerospace Eng., Coll. of Eng., Sunchon Natnl. Univ., 315 Maegok-dong, Sunche ...;Department of Mechanical Engineering, College of Engineering, Seoul National University of Technology, Gongreung 2-dong, Nowon-gu, Seoul 139-743, Korea. E-mail: jysung@snut.ac.kr;School of Mechanical and Aerospace Engineering, College of Engineering, Sunchon National University, 315 Maegok-dong, Suncheon, Jeonnam 540-742, Korea

  • Venue:
  • Journal of Visualization
  • Year:
  • 2008

Quantified Score

Hi-index 0.00

Visualization

Abstract

The three-dimensional vortical structures formed in the wake behind a road vehicle were measured using a particle image velocimetry (PIV) technique and the change of the structures by the existence of an air spoiler was investigated. The measurements were carried out in several x-y, y-z and z-x planes to obtain full three-dimensional flow fields, including an out-of-plane velocity component, obtained by interpolating the velocities in the other plane. Then, the velocity gradient tensor is evaluated to obtain the vortex core by the λ$_2$-definition. The relationship between streamwise, longitudinal and spanwise vortices is systematically analyzed by overlapping the vortex lines and vortex cores and the whole flow topology is compared in both cases with and without an air spoiler. As a result, an air spoiler was found to weaken the C-pillar vortices producing strong wing tip vortices, which reduce downwash flow and longitudinal vortices increase in the vertical direction. The recirculation zone formed when an air spoiler is installed is higher and narrower than without a spoiler.