上下円板の回転による円筒容器内の渦崩壊の流動機構(流体工学,流体機械)

概要

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Experimental and numerical studies are reported on the vortex breakdown phenomenon in an enclosed cylindrical container in which a top endwall rotates at an angular velocity Ω, and a bottom endwall rotates at an angular velocity Ω_b, and a colinder sidewall is stationary. Regime boundaries for the vertex breakdown, the location of the stagnation point of breakdown bubble and the attendant global flow features are in good agreement between the experimental and numerical results. The flow behavior is examined an |Ω_b/Ω| was varied for several combinations of the cylinder aspect ratios and the rotational Reynolds numbers based on Ω. For a co-rotation (Ω_b/Ω>0), the breakdown bubble is located closer to the bottom endwall. For sufficiently large values of Ω_b/Ω, the bubble adheres to the bottom endwall. When Ω_b/Ω becames close to 1, the meridional-plane flow tends to become antisymmetric with respect to the midplane of the cylinder. For a counter-rotation (Ω_b/Ω<0), the bubble moves toward the top endwall. Finally, as |Ω_b/Ω| is further increased, the bubble ceases to exist. The Brown and Lopez criterion based on the production of the negative azimuthal vorticity is considered using the present numerical results.
一般社団法人日本機械学会の論文
2006-10-25