G402 切り欠きのある円柱の抵抗低減 : ストローハル数と表面流れ(2)(GS-4-1 飛翔体,円柱,一般セッション)

概要

論文の詳細を見る
The drag reduction of a circular cylinder with small grooves was investigated. The positions of upstream and downstream sides of the grooves on the cylinder, θ_f and θ_r, were 50-70°, 55-74° and 60-78° from the stagnation point of the cylinder. Experiments were performed for the above three models and smooth cylinder varying the attack angle α = 0 to 30° in the range of Reynolds number Re = 10^4〜10^5. The Strouhal number of the cylinder with grooves increases from 0.20 to 0.28〜0.30. The surface oil-flow patterns show that the shear layers separated from the front groove of the cylinder reattach on the rear groove of the cylinder. This phenomenon caused by the turbulent transition and turbulent separation. From the previous correlations between drag coefficient and Strouhal number of a circular cylinder with tripping wires, it is expected that the drag coefficient of the circular cylinders with small grooves decreases to about half of that of a smooth cylinder at α + θ_f<80°, in the range of Re >4×10^4.
一般社団法人日本機械学会の論文
2006-10-28