だ円板後流の乱流特性

概要

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The near and intermediate wakes of an elliptic disk with the aspect ratio of 2 and 3 are studied at the Reynolds number of 2.0×10^4. The axis switching is found, for the first time, to exist in the elliptic wake. Another striking aspect is periodic velocity fluctuations with two dominant frequencies in the wake. For the elliptic disk with aspect ratio of 2,one of the frequencies is 0.12 in the minor-axis plane and the other is 0.08 in the major-axis plane, if normalized in the form of the Strouhal number. These frequencies are generated by large-scale vortices shed, in antiphase, from the nearwake region. The maximum velocity defect, maximum turbulence intensity and the geometric average of the half width in the major-axis and minor-axis plane follow the law of evolution of the far wake of axisymmetric bodies in the downstream region more than 15 minor-axis diameters away.
社団法人日本機械学会の論文
1997-05-25