逆圧力勾配下の平板上に生じるはく離流れ挙動の解明 : 第2報,相互相関係数を用いた三次元非定常流れ構造の評価(流体工学,流体機械)

概要

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Three-dimensional measurements of cross-correlation coefficient of velocity fluctuations are carried out to investigate flow behaviors of two-dimensional separated flows over a flat plate under an adverse pressure gradient. The velocity fluctuations are obtained with two I-type hotwire probes, one of which is fixed near the flat plate and the other traverses the flow region. The results show that regions with positive and negative cross-correlation distribute checkerwise in a vertical section parallel to the main flow and three-dimensionality of the region with positive correlation near the flat plate grows as the region flows down, whereas spanwise two-dimensionality of the negative region above it holds. In addition, time sequences of the correlation distributions tell that advection velocities of the separated flow structures are about 0.3 times as large as the inflow velocity. Simulations with simplified potential vortices are also made to specify the three-dimentional flow structure of the separation. They illustrate that alternate rows of arch-shaped vortices formed immediately downstream of the separation can reproduce well the characteristics of the experimental results.
社団法人日本機械学会の論文
2007-11-25