円管内パフの発生メカニズム  [in Japanese] Generation of Puffs in a Pipe  [in Japanese]

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Abstract

遷移レイノルズ数領域の管内流でパフと呼ばれている極めて個性的な乱流塊が発生することが知られている.このパフは極めて安定であり, 自己維持機能を持っている.この特性についてはすでに何人かの研究者によって調べられているがこの発生のメカニズム, 自己維持機能のダイナミックス, 等不明の部分が多い.この論文は, 特に, パフの発生メカニズムについて述べたものである.このメカニズムを知るには上流と下流とで同時に流れの構造を決定する必要がある.この決定のために熱線風速計を使った.上流側の熱線が下流側の流れの構造を極力変化させないように特別に設計した熱線を用いて流速を決定した.測定したレイノルズ数は約2200で, 管入口付近の乱れがパフに変わる過程, パフの発生のための必要条件等が明らかにされた.

It is well known that a peculiar turbulent lump called a “puff” appears in a transitional pipe flow. The puff is stable and has a self-sustained mechanism. Several authors have reported on remarkable characteristics of puffs. However, the condition for the generation of puffs has hardly been studied, because it is very difficult to measure the flow properties simultaneously at different axial locations without disturbing the downstream condition. In order to know the generation, two specially designed hot wires were set upstream to measure the initial growth of the puff, and a third wire was located far downstream for detection of equilibrium puffs. Experiments were made at Reynolds numbers near 2200. In two inlet conditions of the pipe, the effect of the strength of inlet disturbances on the generation was investigated. As a result, conditions for the generation and growth of puffs were clarified.

Journal

  • Journal of Japan Society of Fluid Mechanics

    Journal of Japan Society of Fluid Mechanics 12(2), 147-156, 1993-06-30

    The Japan Society of Fluid Mechanics

References:  6

Cited by:  4

Codes

  • NII Article ID (NAID)
    10008003563
  • NII NACSIS-CAT ID (NCID)
    AN00175191
  • Text Lang
    JPN
  • Article Type
    Journal Article
  • ISSN
    02863154
  • Data Source
    CJP  CJPref  J-STAGE 
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