ノズル内の二次元物体後流によってフラッピングする二次元噴流の渦構造(流体工学,流体機械)

概要

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It is possible to control the spread of a plane jet passively by the vortices from a two-dimensional cylinder installed in the nozzle contraction. In a particular condition of cylinder placement, two distinctive spectral peaks at frequencies f1 and f2 with their averaged frequency at 1/2 the vortex shedding frequency fv were observed, where the jet exhibits flapping motion at low frequency f3 (= f1-f2). The vortex structures in a plane jet under inharmonic excitation were studies by means of hotwire and phase ensemble-averaging techniques. The phase ensemble-averaging results show that the vortex street shed at frequency fv/2 was formed in the jet under inharmonic excitation, and similar vorticity distributions appeared in the upper and lower shear-layers alternately at frequency f3. As the result, within the duration of one flapping motion, successive nine vortices were formed at shedding frequency fv/2 to complete their one cycle of evolution.
一般社団法人日本機械学会の論文
2004-11-25