2022 Fiscal Year Final Research Report
Study on coupling mechanism of acoustic vibration and propagating premixed flame by using laser irradiation method
| Project/Area Number |
18H03755
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| Research Category |
Grant-in-Aid for Scientific Research (A)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Review Section |
Medium-sized Section 19:Fluid engineering, thermal engineering, and related fields
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| Research Institution | Hokkaido University |
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Principal Investigator |
Fujita Osamu 北海道大学, 工学研究院, 教授 (10183930)
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| Co-Investigator(Kenkyū-buntansha) |
橋本 望 北海道大学, 工学研究院, 准教授 (70392751)
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| Project Period (FY) |
2018-04-01 – 2023-03-31
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| Keywords | 燃焼振動 / 予混合火炎 / 燃焼速度 / 音響モード / ガスタービン / アンモニア燃焼 / Velocity coupling |
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| Outline of Final Research Achievements |
The downward flame propagation and its instability of C2H4/O2/CO2 premixed gas in a top open tube was investigated. It was found that combustion instability together with enhanced acoustic vibration were more likely to occur in longer tubes and smaller inner diameters. Assuming that the main amplification mechanism of combustion instability is velocity coupling, the theoretically predicted trend can well explain the experimental results. The pressure growth rate was also investigated by changing the flame area using the laser-heated flame surface curvature control method, and it was found that there is a proportional relationship between the flame area and the pressure growth rate. These results indicate that the main combustion instability mechanism in the system under study is velocity coupling. It was also found experimentally that the instability increases when NH3 is mixed with hydrocarbon fuel.
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| Free Research Field |
熱工学
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| Academic Significance and Societal Importance of the Research Achievements |
ガスタービン燃焼器の高効率化に向けて希薄予混合燃焼の導入が広がっている。この際最も困難な課題が燃焼振動の抑制である。本研究では燃焼振動発生に対する燃焼容器形状（長さ、内径）の影響を調べるとともに、その不安定性が現れる機構を示した。すなわち、不安定性が生じる主要機構がVelocity couplingであることを示しており、燃焼振動を抑制するうえで火炎面の変形やセル構造の制御が重要な役割を果たしうることを示している。また、今後カーボンニュートラル実現に向けて利用の広がることが見込まれるNH3に関して、この燃料の導入が燃焼不安定性を増加させる可能性のあることを指摘している。
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