E314 可変直径オリフィスによる渦輪の形成(E-31 乱流渦構造(1),一般講演)

概要

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The experiments in this paper describe the use of a variable aperture vortex ring generator, which has been successfully employed to generate thick cored vortex rings, similar to a Hill's spherical vortex. Gharib (1998) showed that if the stroke length to piston diameter, L/D, exceeded a critical limit (Formation Number) for a fixed diameter vortex ring generator, the leading vortex ring would pinch-off from the trailing jet. This point fixed the upper limit of the non-dimensional ring strength. The variable diameter orifice has been found to delay the pinch-off process, enabling the generation device to continue to feed circulation, impulse and kinetic energy to the ring in order to produce a thick cored vortex ring. It was found that opening aperture was not successful in terms of producing a thick cored vortex ring, contrary to the suggestion Mohseni (2001). Closing the aperture during ring generation resulted in the formation of a thick cored ring.
日本流体力学会の論文
2004-08-09