1998 Fiscal Year Final Research Report Summary
In-situ Spectroscopic Measurement of Turbulent Flame-Front Structure
| Project/Area Number |
09650241
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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 | KOBE UNIVERSITY |
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Principal Investigator |
IKEDA Yuji Kobe University Center for Instrumental Analysis, Associate Processor, 機器分析センター, 助教授 (10212789)
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| Project Period (FY) |
1997 – 1998
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| Keywords | Turbulent flame / Local chemiluminescence measurement / In-situ sensor / Cassegrain optics / High temporal and spatial resolution / Flame-front / Local flame Spectra / OH^*, CH^* and C2^* radicals |
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| Research Abstract |
Local chemiluminescence measurements of OH*, CH* and C2* radicals were carried out in turbulent premixed methane flame to make clear the details of flame-front structures and chemical reactions in the reaction zone. For this measurement, specially designed Cassegrain Optics, which has a high spatial resolution as small as an LDV measurement volume, was developed. Furthermore, to achieve a high temporal resolution, each chemiluminescence was detected by PM tube at sampling rate of 250kHz.
Simultaneous measurements of these three radicals and velocity by LDV were performed to obtain flame-front structure, flame propagating speed and flame thickness. Local Damkoler number were measured directly at the flame-front and their fine scale were demonstrated.
The probability density function (PDF) of OH* emission showed bi-modal peaks across the flame-front location corresponding to wrinkled laminar flame or flamelet region. The first peak of the OH* PDF was corresponding to the high temperature region outside of the flame cone and the secondary peak was associated with chemical reaction at the primary reaction zone. Time series signals of local OH*, CH* and C2* emission intensities in wrinkled laminar flame region showed irregular peaks which, however, correspond to each other in the three chemiluminescence signals. This results indicated strong linkage between OH-C H-C2 reactions at wrinkled laminar flame-front. The flame-front thickness measured by CH and C2 emissions were 0.1-0.3mm, while that was about 1.0mm by OH* emissions. Furthermore, local reaction rate and local mixture strength at turbulent flame-front are examined from local CH* and C2* emission intensities in comparison with measured data bases of these emissions in laminar premixed flame.
A new optical diagnostics to examine local flame-front structure and flame chemistry by means of local chemiluminescence measurement was proposed and its performance was proven.
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