平板境界層における遷移過程に対する主流乱れ成分の影響(安定性・乱流境界層・せん断流・遷移(2),一般講演)

概要

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An experimental study of laminar turbulent transition in a flat plate boundary layer subjected to free stream turbulence has been carried out. This report focuses on effect of the intensity of free stream turbulence on transition process. In case of the free stream turbulence of υ_<rms, ∞>/U_∞=0.67% wall-normal velocity fluctuation, flow visualization clearly shows that a packet of Tollmien-Schlichting (T-S) wave emerges in the boundary layer and immediately breaks down to turbulence with deformation to Λ-shape structures. However, in a much weaker turbulence intensity case, the transition scenario seems that a short streak breakdown coexists with the T-S wave breakdown. At least, there are three scenarios, which are longitudinally elongated streaks breakdown, Λ-shape deformation of the local T-S wave packet and a short streak breakdown, in boundary layer transition due to free stream turbulent.
日本流体力学会の論文
2009-09-02