1939 リング設置による円柱からの渦放出抑制(S21-7 噴流,後流及びはく離流れの流動解析と応用(7),21世紀地球環境革命の機械工学:人・マイクロナノ・エネルギー・環境)

概要

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Omnidirectional reductions in drag and fluctuating forces were achieved for a circular cylinder subjected to cross-flow by attaching cylindrical rings along its span at an interval of several diameters. In this work, the ring configuration, the diameter D, spanwise width W, and spanwise pitch P, was systematically varied in order to explore the optimum configuration for the vortex shedding suppression. The Reynolds number based on the cylinder diameter d was Red , 30000. As a result, it was found that the periodic pressure fluctuation on the sides of the cylinder due to the alternating vortex shedding was disappeared for the smaller pitch of P/d ≤ 4 at D/d = 1.3 and W/d = 1. This is likely to be related to the non-existence of the two-dimensional flow field in the near wake between two adjacent rings, due to the smaller axial spacing of the rings.
2008-08-02