二次元乱流噴流中に発生するFlapping現象の統計評価

概要

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The flapping motion in a two-dimensional turbulent jet is analyzed statistically. The analysis is done by applying a continuous wavelet transform with Gabor mother wavelet to the experimental result of hot-wire anemometer. The analysis results show that the flapping motion is clearly recognized by the present new method. The flapping motion occurs at random, and the average time interval of flapping motion is about 6.1 times the flapping periods (0.24 sec). The average duration time of the flapping motion is about 1.7 times the flapping period (0.07 sec) and the one that continues over 3.0 times the flapping period is very few. The negative value of the two-point spatial velocity correlation substantially depends on whether the flapping motion arises or not. From these results, it is found that the flapping motion in a two-dimensional turbulent jet has a very important role to the properties of the jet though the flapping motion is a rare phenomenon.