周期的吹き出しによる円管助走部境界層の乱流遷移（孤立乱流塊の発生条件）

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概要

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• The laminar-turbulent transition of a boundary layer induced by an ejection of jet in the inlet region of a circular pipe was experimentally investigated. The jet was periodically inserted radially from a small hole in the inlet region into the pipe flow. Axial velocity was monitored by a hot-wire anemometer. The difference of properties in laminar-turbulent transition from developed Hagen-Poiseuille flow was examined. Isolated turbulence patches were generated by the jets, and then they propagated downstream. The leading edge of the turbulent patch was definite, whereas its trailing edge was not. This characteristic was similar to that of a turbulent spot in a flat-plate boundary layer. The threshold value of the jet flow rate to generate the turbulent patch was then obtained. The threshold value decreased and saturated finally with the increase in jet duration. The normalized jet duration when the threshold value was saturated increased with the increase in Reynolds number, contrary to the developed region. The normalized threshold flow rate tended to vary with the Reynolds number among three regions. All tendencies were different from those of the developed region. With the increase in jet flow rate beyond the threshold value, the duration of the turbulent patch increased, though the fluctuating velocity within the patch did not increase. The propagation velocities of the leading and trailing edges, the duration and fluctuating velocity within the turbulent patch were almost constant irrespective of the jet ejection frequency.

著者

• 一宮 昌司

  徳島大学大学院ソシオテクノサイエンス研究部

• 玉谷 純二

  徳島大学大学院ソシオテクノサイエンス研究部

• 藤村 勇斗

  徳島大学大学院

関連論文

• 円管助走部境界層の単一突起による遷移 : 定常乱流領域の発達過程(流体工学,流体機械)
• 2. 非圧縮性流れ : 2・2 境界層 (機械工学年鑑(1995年)流体工学)
• 周期的吹き出しによる円管助走部境界層の乱流遷移（孤立乱流塊の発生条件）
• ２次元噴流出口混合層に及ぼす局所周期撹乱の効果
• ２次元噴流出口混合層に及ぼす局所周期撹乱の効果（乱流遷移過程の空間構造と定量的表示）
• コルモゴロフ複雑度による乱流のランダムさ表現（混合層の場合）
• 周期的吹き出しによる円管助走部境界層の乱流遷移（孤立乱流塊内部の乱れと乱流塊の成長機構）
• Laminar-Turbulent Transition of an Inlet Boundary Layer in a Circular Pipe Induced by Periodic Injection (Shape of Isolated Turbulent Patches and Their Growth)
• 圧力式ホモジナイザーの乳化メカニズムに関する研究

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