S0504-5-3 流れ方向に強制振動している直角二等辺三角柱からの渦放出(噴流,後流および剥離流れの流動解析と応用(その5))

概要

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In this study, the flow features of vortex shedding from a right-angled isosceles triangular cylinder oscillating along the direction of the flow were observed by visualizing water flow experiment at the ranges of the frequency ratiof/f_λ=0〜9, amplitude ratio 2a/d=0.125, 0.25, 0.5 and 0.75, and Reynolds number Re=1900. The variations of mean vortex shedding frequency were investigated and the existence range of the lock-in was shown. As a result of the experiments, ten kinds of representative flow patterns were observed and the distributions of the flow pattern in the lock-in area were obtained. It was shown that the lock-in is caused in unsymmetrical state of the installation for the flow. It has been understood that the generation of the lock-in is intermittent though the range of the lock-in for a right-angled isosceles triangular cylinder extends compared with the case of the circular cylinder. When the triangular cylinder is unsymmetrical installation, it has been understood that the lock-in area changes depending on the installation posture. This result will be able to become an effective clue to evade the lock-in phenomenon.
2009-09-12