Chinese Journal of Theoretical and Applied Mechani ›› 2013, Vol. 45 ›› Issue (5): 772-776.DOI: 10.6052/0459-1879-12-361

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TR PIV INVESTIGATION ON THE LAGRANGIAN HAIRPIN VORTICES INDUCED BY A CUBIC DISTURBANCE

Quanji Zhuojun1, Jiang Nan2,3, Tang Zhanqi2   

  1. 1. Tianjin Bureau Quality and Technical Supervision, Tianjin 300192, China;
    2. Institute of M Department of Mechanical Engineering, Tianjin University, Tianjin 300072, China;
    3. Tianjin Key Laboratory of Modern Engineering Mechanics, Tianjin 300072, China
  • Received:2013-06-09 Revised:2013-08-22 Online:2013-09-23 Published:2013-10-23
  • Supported by:

    The project was supported by the National Natural Science Foundation of China (11332006, 11272233), the National Program on Key Basic Research Project (973 Program) (2012CB720101) and opening subjects of The State Key Laboratory of Nonlinear Mechanics(LNM), Institute of Mechanics, China Academy of Science.

Abstract:

The hairpin vortices structure induced by a cubic disturbance with a frequency of 2.1 Hz are investigated by time-resolved particle image velocimetry (TR PIV) from both the Euler and Lagrangian view. Firstly, the hairpin vortices' heads could be clearly distinguished form the side-view database, which also indicates that the hairpin heads lift up when convecting down streamwise. Then, the finite-time lyapunov exponents (FTLE) method is utilized to describe the lagrangian hairpin vortices induced by the cubic. It could be seen that FTLE clearly shows both the projection of the hairpin heads and the hairpin necks in the streamwise and spanwise plane. Furthermore, two-point correlation of FTLE at different reference positions along the streamwise indicate that the hairpin vortices statistically with an increasing inclined angle with the flat plate while they are moving downstream.

Key words:

Lagrangian hairpin vortices|finite-time lyapunov exponents|cubic disturbance|TR PIV

CLC Number: