814 直交流中の円柱からの渦放出に及ぼすフィンの効果

Abstract

The effect of simple spiral fin around a bare tube on Karman vortex shedding was experimentally investigated. We measured the distributions of mean velocity, the intensity of velocity fluctuation, the spectrum of velocity fluctuation and the coherence distribution of Karman vortex in the spanwise direction. And the flow around a fin tube was visualized by using smoke wire technique. As a result it was made clear that Karman vortex in the near-wake of the fin tube make the cell structure with the scale of pitch length of the fins. The large scale vortex was formed by the reconnection of the vortex cells.