円柱の下流に十字交差配置された帯状の平板による振動制御 : 第1報,固定系からの縦渦流出(流体工学,流体機械)  [in Japanese] Vibration Control for a Circular Cylinder by a Strip-plate Set Downstream in Cruciform Arrangement : 1st Report, Influence of a Downstream Strip-plate on the Shedding of Longitudinal Vortices from Fixed System(Fluids Engineering)  [in Japanese]

The specific aim of this work is to develop a new technique to control the vibration of a circular cylinder by utilizing the effect of downstream cylindrical body in cruciform arrangement. In this work, a strip-plate with a width w equal to or smaller than the cylinder diameter d is selected as the downstream body. In this report, results of observation of flow visualization in water tunnel and measurements in wind tunnel for fixed systems are presented. The two longitudinal vortices, the trailing and the necklace vortices which were found to induce vibrations of the upstream cylinder in the cruciform two-circular system, are observed around the crossing of the circular-cylinder/strip-plate system. Either of the two longitudinal vortices is observed to shed periodically when w/d is 0.50 or 0.62, depending on the gap-to-diameter ratio s/d. While, periodic shedding of the necklace vortex is not observed when 0.75<s/<f<1.0.