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SEPARATION OF SMALL BUBBLE FROM GAS FLOW INJECTED INTO TURBULENT BOUNDARY LAYER

Research Project

Project/Area Number 13650190
Research Category

Grant-in-Aid for Scientific Research (C)

Allocation TypeSingle-year Grants
Section一般
Research Field Fluid engineering
Research InstitutionOSAKA CITY UNIVERSITY

Principal Investigator

KATOH Kenji  Department of Mechanical Engineering, Osaka City University, Associate Professor, 大学院・工学研究科, 助教授 (10177438)

Co-Investigator(Kenkyū-buntansha) AZUMA Tsuneo  Department of Mechanical Engineering, Osaka Citv University, Professor, 大学院・工学研究科, 教授 (40047329)
Project Period (FY) 2001 – 2002
Project Status Completed (Fiscal Year 2002)
Budget Amount *help
¥500,000 (Direct Cost: ¥500,000)
Fiscal Year 2002: ¥500,000 (Direct Cost: ¥500,000)
KeywordsSmall Bubble / Turbulent Boundary Layer / Surface Tension / Gas-Liquid Interface
Research Abstract

The turbulent drag is drastically reduced when a large quantity of small bubbles are injected into a liquid turbulent boundary layer. Recently this phenomenon is applied to a technique of energy conservation. It is known that the drag reduction is remarkably influenced by the bubble size. However, a large quantity of bubbles are generally injected in most experiments and there have been few reports concerning to the formation of individual bubble.
In this research, we investigate the formation of small bubble separated from gas flow injecting to a turbulent boundary layer from a single submerged orifice. The behavior of gas flow and of bubble separation was observed in detail by high-speed digital video camera under various free stream velocities and gas velocities near the orifice with diameter from 0.2 to 0.4mm. Referring to the observation, the diameter of single bubble was theoretically obtained from the force balance on the ellipsoidal bubble by considering form drag, lift, inertia due to virtual mass of bubble, surface tension, buoyancy and gas inertia. The results roughly agree with those measured by experiment.
When the gas velocity becomes large, the gas flow forms a long cylindrical jet with long tail in the downward direction. The jet is torn off on the orifice due to the large drag from the surrounding turbulent flow. However, the injected gas from the orifice immediately impacts the jet and coalesces. The repetition of this phenomena results in continuous cylindrical jet on the orifice. From the observation by the high-speed video camera, the bubble separates from middle part of the jet due to instability on gas-liquid interface, The configuration of cylindrical jet was calculated from a theoretical model considering various forces acting on the jet, The solution of differential equation calculated numerically qualitatively agrees with that of actual jet configuration.

Report

(3 results)
  • 2002 Annual Research Report   Final Research Report Summary
  • 2001 Annual Research Report
  • Research Products

    (15 results)

All Other

All Publications (15 results)

  • [Publications] 加藤健司, 東 恒雄: "接触角の履歴現象に及ぼす残留気泡・液滴の影響"日本機械学会論文集B編. 67巻659号. 1793-1800 (2001)

    • Description
      「研究成果報告書概要(和文)」より
    • Related Report
      2002 Final Research Report Summary
  • [Publications] Katoh, K., Azuma, T.: "Similarity between Heat and Momentum Transfer in Turbulent Flow"Thermal Science and Engineering. Vol.10, No.4. 5-6 (2002)

    • Description
      「研究成果報告書概要(和文)」より
    • Related Report
      2002 Final Research Report Summary
  • [Publications] 加藤健司, 東 恒雄: "水平円柱側壁に沿って流下する液膜流の挙動に関する研究(第2報,液膜表面に現れる定在波の増幅機構)"日本機械学会論文集B編. 68巻673号. 2475-2481 (2002)

    • Description
      「研究成果報告書概要(和文)」より
    • Related Report
      2002 Final Research Report Summary
  • [Publications] 加藤健司, 東 恒雄: "水平円柱側壁に沿って流下する液膜流の挙動に関する研究(液膜のはく離機構)"日本機械学会論文集B編. 69巻(掲載予定). (2003)

    • Description
      「研究成果報告書概要(和文)」より
    • Related Report
      2002 Final Research Report Summary
  • [Publications] 加藤健司, 東 恒雄: "渦発生体付き流路における圧力損失と伝熱促進の関係について"日本機械学会論文集B編. 69巻(掲載予定). (2003)

    • Description
      「研究成果報告書概要(和文)」より
    • Related Report
      2002 Final Research Report Summary
  • [Publications] Kenji Katoh and Tsuneo Azuma: "The Effect of Residual Bubble and Drop on the Hysteresis Phenomenon of Contact Angle"Transactions of The Japan Society of Mechanical Engineers, Series B. 67-659. 1793-1800 (2001)

    • Description
      「研究成果報告書概要(欧文)」より
    • Related Report
      2002 Final Research Report Summary
  • [Publications] Kenji Katoh and Tsuneo Azuma: "Similarity between Heat and Momentum Transfer in Turbulent Flow"Thermal Science and Engineering. 10-4. 5-6 (2002)

    • Description
      「研究成果報告書概要(欧文)」より
    • Related Report
      2002 Final Research Report Summary
  • [Publications] Kenji Katoh and Tsuneo Azuma: "Characteristics of Liquid Film Flowing around Side Wall of a Horizontal Circular Cylinder (Amplification of Standing Wave Appearing on the Film Surface)"Transactions of The Japan Society of Mechanical Engineers, Series B. 68-673. 2475-2481 (2002)

    • Description
      「研究成果報告書概要(欧文)」より
    • Related Report
      2002 Final Research Report Summary
  • [Publications] Kenji Katoh and Tsuneo Azuma: "Characteristics of Liquid Film Flowing around Side Wall of a Horizontal Circular Cylinder"Transactions of The Japan Society of Mechanical Engineers, Series B. in print. (2003)

    • Description
      「研究成果報告書概要(欧文)」より
    • Related Report
      2002 Final Research Report Summary
  • [Publications] Kenji Katoh and Tsuneo Azuma: "Heat Transfer Enhancement and Pressure Loss in Channel with Vortex Generator"Transactions of The Japan Society of Mechanical Engineers, Series B. in print. (2003)

    • Description
      「研究成果報告書概要(欧文)」より
    • Related Report
      2002 Final Research Report Summary
  • [Publications] 加藤健司, 東 恒雄: "接触角の履歴現象に及ぼす残留気泡・液滴の影響"日本機械学会論文集B編. 67巻659号. 1793-1800 (2001)

    • Related Report
      2002 Annual Research Report
  • [Publications] 加藤健司, 東 恒雄: "水平円柱側壁に沿って流下する液膜流の挙動に関する研究(第2報,液膜表面に現れる定在波の増幅機構)"日本機械学会論文集B編. 68巻673号. 2475-2481 (2002)

    • Related Report
      2002 Annual Research Report
  • [Publications] 加藤健司, 東 恒雄: "水平円柱側壁に沿って流下する液膜流の挙動に関する研究(液膜のはく離機構)"日本機械学会論文集B編. 69巻(掲載予定). (2003)

    • Related Report
      2002 Annual Research Report
  • [Publications] 加藤健司, 東 恒雄: "渦発生体付き流路における圧力損失と伝熱促進の関係について"日本機械学会論文集B編. 69巻(掲載予定). (2003)

    • Related Report
      2002 Annual Research Report
  • [Publications] 加藤健治, 東恒雄: "接触核の履歴現象に及ぼす残留気泡・液滴の影響"日本機械学会論文集 B編. 67巻659号. 1793-1800 (2001)

    • Related Report
      2001 Annual Research Report

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Published: 2002-04-01   Modified: 2016-04-21  

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