Behavior of a Triple Flame Changing in Concentration Gradients
| Project/Area Number |
12650212
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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 | Keio University |
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Principal Investigator |
MIZOMOTO Masahiko Keio University, Faculty of Science and Technology, Professor, 理工学部, 教授 (60051710)
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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 |
¥3,700,000 (Direct Cost: ¥3,700,000)
Fiscal Year 2001: ¥500,000 (Direct Cost: ¥500,000)
Fiscal Year 2000: ¥3,200,000 (Direct Cost: ¥3,200,000)
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| Keywords | Triple Flame / Concentration Gradient / Premixed Flame / Diffusion Flame / Burning Velocity / Burning Intensity / OH Radical / Unsteady / 相互干渉 / PIV / レーザートモグラフィ / メタン空気火炎 |
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| Research Abstract |
Characteristics of a 2D methane-air triple flame are made clear in various fuel concentration gradients. In this research non-dimensional concentration gradients (Cm/xm) are defined originally.
At the stationary condition, OH radical luminous intensity is measured by using an interfering filter. The results show that the OH radical luminous intensity does not correlate with flame heat values at gentle concentration gradients (Cm/xm<2.5). This region (Cm/xm<2.5) is defined as a triple flame region mainly composed of premixed flame (region I).
Next, flame positions and distributions of luminous intensity are measured from visible flame images. The flow field and thermal structure at the leading edge of the triple flame are also measured by PIV and laser tomography. From these results, we define the region (Cm/xm>50.0 〜 50.9) as a triple flame region mainly composed of non-premixed flame (region II). And the region between region I and region II (2.5<Cm/xm<50.0 〜 50.9) is defined as the nor
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mal triple flame region (region III). A burning velocity of the triple flame composed of premixed mixture with a concentration gradient is larger than the maximum burning velocity of a premixed flame formed in the uniform mixture. There is a flame interaction between the premixed flame wing and the non-premixed flame. Because of this interaction effect, Hie flame intensity goes up with the increase of the concentration gradient.
The transitional response of triple flame is studied using the instantaneous change of concentration gradient from steep to gentle or vise versa. Under the condition from steep to gentle, there is a lag between the time of reaching the concentration change to the flame and the time of opening the premixed flame wing. This phenomenon is due to the flame interaction, especially the merging effect between the non-premixed flame and the rich premixed flame. The results of the stationary condition indicate that merging effect acts at region III. When the concentration gradient change in unsteady state at the combustor, we have to consider the time lag of transition from region II to region III. Less
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Report
(3 results)
Research Products
(7 results)
