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2005 Fiscal Year Final Research Report Summary

Study on self-exciting structure of cloud-cavitation flow

Research Project

Project/Area Number 16560161
Research Category

Grant-in-Aid for Scientific Research (C)

Allocation TypeSingle-year Grants
Section一般
Research Field Fluid engineering
Research InstitutionKanazawa Institute of Technology

Principal Investigator

SATO Keiichi  Kanazawa Institute of Technology, College of Engineering, Professor, 工学部, 教授 (50113030)

Co-Investigator(Kenkyū-buntansha) SAITO Yasuhiro  Kanazawa Institute of Technology College of Engineering, Assistant Professor, 工学部, 講師 (00319039)
Project Period (FY) 2004 – 2005
KeywordsCavitation / Cloud cavitation / Self-exciting phenomena / High impact / Pressure wave / High speed observation / Image processing / High speed liquid flow
Research Abstract

Attached cavitation has a shedding and collapsing of cavitation clouds and high impact under constant flow condition. The understanding of this phenomenon is very useful from a viewpoint of the development of basic engineering and the positive application of cavitation impact for the industrial purpose.
The mechanism of the periodicity remains to be solved though it is considered as one of self-exciting phenomena peculiar to cavitation flow. The researchers in this project have made clear the existence of jet flow to the main stream from the inside of attached cavity when a re-entrant motion reaches the leading-edge of the attached cavity. After the jet as a kind of trigger vortex cavities form, coalescence, and shed downstream as a large cavitation cloud.
In this study the occurrence of large pressure waves is focused on which is caused by the collapse of cavitation cloud. First the existence of pressure waves and the chain-reaction-type propagation of bubble collapses to the surroundin … More g bubbles was experimentally shown at the collapse of Karman-vortex-type cavity shed from a circular cylinder. In addition the coalescence mechanism and the existence of pressure wave are examined about the periodic shedding in cavitating water jet. Especially an image processing method is developed to investigate quantitatively the rapid collapse and deformation of bubbles. Based on this image processing technique, it is shown that a re-entrant motion can be induced by the pressure wave accompanied by the collapse of cavitation clouds.
As a result the following process is pointed out as the mechanism of re-entrant motion concerning the self-exciting structure in the flow of cloud cavitation as follows ; (1) shedding of cavitation clouds from attached cavitation, (2) collapse of shedding cavitation clouds, (3) pressure-wave propagation to the end of attached cavity, (4) chain-reaction collapses of bubbles and re-entrant motion within the attached cavity, (5) arrival of the re-entrant motion at the leading part of attached cavity, (6) roll-up to the main stream at the leading part of attached cavity, (7) formation of vortex cavity and movement to downstream, (8) growth of the vortex cavity and the formation of cavitation cloud Less

  • Research Products

    (10 results)

All 2007 2006 2005

All Journal Article (10 results)

  • [Journal Article] 水中ウォータジェットにおける壁面に衝突するキャビテーションクラウドの高速度観察2007

    • Author(s)
      斉藤康弘
    • Journal Title

      混相流研究の進展 II

      Pages: 掲載決定

    • Description
      「研究成果報告書概要(和文)」より
  • [Journal Article] Instantaneous Behavior of Cavitation Clouds at Impingement of Cavitating2007

    • Author(s)
      Saito, Y, Sato, K.
    • Journal Title

      Progress in Multiphase Flow Research II, The Japanese Society for Multiphase Flow

    • Description
      「研究成果報告書概要(欧文)」より
  • [Journal Article] Instantaneous Behavior of Cavitation Clouds at Impingement of Cavitating Eater-Jet2006

    • Author(s)
      Saito, Y
    • Journal Title

      Proc. Sixth International Symposium on Cavitation

      Pages: 1-5

    • Description
      「研究成果報告書概要(和文)」より
  • [Journal Article] クラウドキャビテーションにおけるレントラント運動とクラウド放出機構に関する検討(収縮拡大流路において)2006

    • Author(s)
      佐藤恵一
    • Journal Title

      日本学術会議キャビテーションに関するシンポジウム(第13回)

      Pages: 1-4

    • Description
      「研究成果報告書概要(和文)」より
  • [Journal Article] Observations of Unsteady Separated-Type Cavitation in Convergent-Divergent Channel2006

    • Author(s)
      Sato, K.
    • Journal Title

      Proc. The 5th International Symposium on Measurement Techniques for Multiphase Flow II

      Pages: 1089-1093

    • Description
      「研究成果報告書概要(和文)」より
  • [Journal Article] Instantaneous Behavior of Cavitation Clouds at Impingement of Cavitating Water-Jet2006

    • Author(s)
      Saito, Y, Sato, K.
    • Journal Title

      Proc. Sixth International Symposium on Cavitation, Paper No.57

      Pages: 1-5

    • Description
      「研究成果報告書概要(欧文)」より
  • [Journal Article] Re-entrant Motion and Shedding Mechanism of Cloud on Cloud Cavitation (Convergent-Divergent Flow Channel)2006

    • Author(s)
      Sato, K., Saito, Y.
    • Journal Title

      Proc. 13th Symposium on Cavitation

      Pages: 1-4

    • Description
      「研究成果報告書概要(欧文)」より
  • [Journal Article] Observations of Unsteady Separated-Type Cavitation in Convergent-Divergent Channel2006

    • Author(s)
      Sato, K., Saito, Y.
    • Journal Title

      Proc. The 5th International Symposium on Measurement Techniques for Multiphase Flow Vol.II

      Pages: 1089-1093

    • Description
      「研究成果報告書概要(欧文)」より
  • [Journal Article] High-speed Deforming Behavior of Cavitation Cloud and Propagation of Bubble Collapse2005

    • Author(s)
      Saito, Y
    • Journal Title

      Proc. The 8th Asian Symposium on Visualization

      Pages: 1-6

    • Description
      「研究成果報告書概要(和文)」より
  • [Journal Article] High-speed Deforming Behavior of Cavitation Cloud and Propagation of Bubble Collapse2005

    • Author(s)
      Saito, Y., Sato, K.
    • Journal Title

      Proc. The 8th Asian Symposium on Visualization, Paper No.19

      Pages: 1-6

    • Description
      「研究成果報告書概要(欧文)」より

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Published: 2008-05-27  

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