Title page for etd-0719115-124451


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URN etd-0719115-124451
Author Ya-shiun Chan
Author's Email Address yashiun_915@hotmail.com
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Department Mechanical and Electro-Mechanical Engineering
Year 2014
Semester 2
Degree Master
Type of Document
Language zh-TW.Big5 Chinese
Title Eulerian and Lagrangian Based Investigation for the Dynamic Stall Phenomenon over a Pitching Airfoil
Date of Defense 2015-07-29
Page Count 53
Keyword
  • Dynamic stall
  • Pitching airfoil
  • Eulerian viewpoints
  • Lagrangian Coherent Structures (LCS)
  • Leading edge vortex (LEV)
  • Trailing edge vortex (TEV)
  • Abstract This study investigates two-dimensional flow over a pitching airfoil by numerical simulation. The simulation results are analyzed by two different viewpoints based on Eulerian and Lagrangian. In Eulerian viewpoints, we have observed that the evolution of leading edge vortex (LEV) and the trailing edge vortex (TEV) by the vorticity η and the normalized second invariant of the velocity gradient tensor Λ. In this study, we have suggested that Λ can present the rotation strength of the LEV and TEV better than the vorticity, and the relationship between the vortex interaction and the variation of lift force are evaluated by the pressure field. Furthermore, the convective, pressure, and diffusion effects during the dynamic stall are discussed by the transport equation of Λ. In Lagrangian viewpoints, we have used Lagrangian coherent structures (LCS) to distinguish regions with different dynamic behavior and observed the variation of LCS by particle group tracking. The underlying flow dynamics of LEV and TEV is observed under this methodology. This study shows that better understandings of the dynamic stall of a pitching foil are acquired by using the LCS approach and the Eulerian method together.
    Advisory Committee
  • Kuang-Chuan Lin - chair
  • Yang-Yao Niu - co-chair
  • Hsin-Fu Huang - co-chair
  • Chien-Chou Tseng - advisor
  • Files
  • etd-0719115-124451.pdf
  • Indicate in-campus at 2 year and off-campus access at 2 year.
    Date of Submission 2015-08-19

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