自己保存条件下の平面壁面噴流の組織構造に及ぼす速度比の影響

概要

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The coherent structure for the plane wall jet under the self-preserving pressure gradient was analyzed to examine the effect of velocity ratio U_m/U_e on the ensemble averaged pattern which, in particular, corresponds to the trunk of a pair of spanwise vortices. Three values of velocity ratio U_m/U_e were used in the range of 2.0 to 4.0. The VITA technique was employed to detect the longitudinal velocity signals. It was inferred from the ensemble averaged patterns of u- and ν- fluctuating velocities that a pair of counter-rotating spanwise vortices has the same event independent of the velocity ratio. The peak ratio R_p in the ensemble-averaged pattern, however, decreases with decreasing velocity ratio. The mean period of the event also decreases with decreasing velocity ratio, while the mean frequency of the event increases. From these results, it was found that the spatial scale of a pair of vortex structures decreases with decreasing velocity ratio.
社団法人日本機械学会の論文
1996-07-25