AM05-04-006 強い主流乱れが励起する境界層撹乱の代数的増幅(境界層とせん断流2,一般講演)

概要

論文の詳細を見る
In the present study a boundary layer flat plate is installed in a free-stream of 2.2m/s and 1.5m/s, which is highly fluctuating owing to grid-generated turbulence. The free-stream turbulence is of about 7% at the leading edge. Under these flow conditions smoke-wire flow visualizations and hot-wire measurements are made to clarify the subcritical boundary layer transition caused by strong free-stream turbulence. It is found that the free-stream turbulence generates elongated streaks, and transition is triggered by the streak instability which can lead to the formation of a turbulent spot. The streak instability starts to occur at R_θ=85 to develop to trigger similar instabilities of the neighboring streaks at R_θ=120. Furthermore we found it to be beyond θ^+=7.3 that the wall friction increases downstream. It is stressed that the critical condition describes the lowest Reynolds number for the boundary layer transition.
日本流体力学会の論文
2005-09-05