| Project/Area Number |
12650201
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Thermal engineering
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| Research Institution | Nagoya Institute of Technology |
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Principal Investigator |
OHIWA Norio Nagoya Institute of Technology, Faculty of Engineering, Professor, 工学部, 教授 (00023341)
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| Project Period (FY) |
2000 – 2001
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| Project Status |
Completed (Fiscal Year 2001)
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| Budget Amount *help |
¥3,600,000 (Direct Cost: ¥3,600,000)
Fiscal Year 2001: ¥1,100,000 (Direct Cost: ¥1,100,000)
Fiscal Year 2000: ¥2,500,000 (Direct Cost: ¥2,500,000)
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| Keywords | Turbulent Premixed Flame / Turbulent Burning Velocity / Vortex-Flame Interaction / Plane Shear Flow / Coherent Structure / Karman Vortex Street / Wake behind Cylindrical Rod Array / Unsteady Propagating Flame / 乱流予混合火炎 / 円柱格子乱流 / 火炎と渦の相互干渉 / 火炎伸長 / トモグラフィー / 火花点火火炎 / ボルテックス・バースティング / 音響励起 / 群島状火炎 |
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| Research Abstract |
In this investigation the processes of vortex-flame interaction of a spark-ignited flame with either coherent structure in the plane premixed shear flow or Karman vortex street in the wake behind a fine cylindrical rod array are experimentally examined, in order to clarify effects of adjacent eddies on the vortex bursting. Propane-air mixture is used in this investigation with an equivalence ratio varied. The results obtained are summarized as follows.
(1) In case of the spark ignition at the center of a large scale organized eddy, a flame propagates faster in the axial direction than in the radial one, indicating that the vortex motion enhances the propagation velocity. After completing combustion within an eddy, a pair of flames protrude to adjacent boundary regions on upstream and downstream sides and propagate in the flow direction. The propagation velocity is promoted by the rolling-up motion inherent in the shear flow. In case of the spark ignition at the boundary between adjacent eddies, a flame extends along the contact surface between two mixture streams and becomes S-shaped. It is found that the flame velocity in the flow direction is almost equal to that in the axial direction. When the tips of S-shaped flame reach adjacent eddies, the vortex bursting again enhances the axial flame propagation. It is concluded that there exist two kinds of vortex-flame interactions; one is the vortex bursting, the other is the vortex boosting, and that combination of these two enhancement mechanisms constitutes one of the key factors to the turbulent combustion.
(2) A spark-ignited young flame generated in the mixture wake behind a fine cylindrical rod array suffers from the intense cooling and stretching by multiple attacks of Karman vortex. The vortex-flame interaction, therefore, can not always augment flame propagation, but lead to flame extinction in the weak mixture.
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