Global Mode Analysis in the L/T Transition of a Hypersonic Boundary Layer Forced by Wall Injection

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• 作者：Thierry André ; ^a ; Evgeniy Orlik^b ; Antoine Durant^c ; Ivan Fedioun^a ; ^{ivan.fedioun@cnrs-orleans.fr" class="auth_mail" title="E-mail the corresponding author}
• 关键词：Hypersonic boundary layer ; Wall injection ; Global mode analysis ; Koopman modes ; Implicit Large Eddy Simulation
• 刊名：Procedia IUTAM
• 出版年：2015
• 出版时间：2015
• 年：2015
• 卷：14
• 期：Complete
• 页码：58-67
• 全文大小：1502 K

文摘

The laminar-turbulent transition of a Mach 4.6 flat-plate boundary layer forced by wall injection is investigated using Implicit Large Eddy Simulation. The boundary layer edge conditions match those of a 1:3 scale hypersonic vehicle forebody at Mach number 6 in the T-313 blow-down wind tunnel of ITAM - Russian Academy of Science. Two different injection pressures are considered. The breakdown to turbulence is observed through instantaneous Q-criterion visualizations and wall pressure fluctuations. Global instability analysis is performed by the computation of Koopman modes from 2D pressure and density snapshots of the ILES flow field. Some coherence is found in the spatial structures and temporal frequencies of global modes computed on two different grids, indicating a weak dependency on grid resolution. Physical insight is gained, confirming different conjectured transition mechanisms for the different injection pressures.