EXPERIMENTAL RESEARCH ON VERY HIGH-INTENSITY COMBUSTION IN HIGH-SPEED PREMIXED GAS FLOW

高速预混气流中极高强度燃烧的实验研究

• 批准号: 63550054
• 负责人: TAKI Shiro
• 金额: $ 1.15万
• 依托单位: FUKUI UNIVERSITY
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for General Scientific Research (C)
• 财政年份: 1988
• 资助国家: 日本
• 起止时间: 1988 至 1989
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-63550054/
• 关键词: Turbulent premixed flame; Deflagration detonation transition; Detonation; High-intensity combustion; 高速燃焼; デフラグレーション; デトネーション

Very high-speed combustion or very high-intensity combustion would be possible in two types, which are the very intense turbulent flames and the detonations. Both types in premixed gases are generated from propagating flames. In the presence of obstacles in the combustible gas, the turbulence is produced by the induced flow. The turbulence will increase the transport of mass and energy and the area of flame front, leading to the increase in the rate of combustion reactions and, hence, to the enhancement of the pressure waves. All these effects to increase the burning rate depend on the induced flow velocity, which in turn depends on the burning rate itself. This relation is able to form a positive feedback system. Based on this idea, we found that the propagating flame can easily be accelerated even in fully unconfined gas mixtures when comb-shaped grids are placed repeatedly in the flame path.In the present research, we investigate the structures of the very high-speed deflagration an … More d the mechanisms of the transition to detonation. They are observed by schlieren framing or streak photographs, using a high-speed camera. The brightness of the flames is also observed at a point where the light emissions are measured by photocell system. The transient pressure waves are measured by piezoelectric pressure transducers. The combustible gases we used are the stoichiometric mixtures of methane, ethane or hydrogen with oxygen slightly diluted by nitrogen, argon or helium. Deflagration of any mixtures can be accelerated to any velocity by repeated obstacles. The noticeable accelerations of the flames are observed just after disappearing of the large eddies formed behind obstacles, or grid wires. The accelerating flames seen by schlieren framing photographs, look as fine grain which are much smaller than the scales of turbulence in the other burning regions. The fine and intense turbulent flames generate blast waves, as observed by pressure measurements. The mechanisms of the flame acceleration do not depend on the kind of mixtures we used. For any mixture the transition of deflagration to detonation does occur, but the onset of detonation of methane mixtures delays up to over 1000 m/s of flame speed. The very fast deflagration forms "shock + flame" structure. Less

非常高速或非常高强度的燃烧有两种可能，即非常强烈的湍流火焰和爆炸。这两种类型的预混气体都是由火焰传播产生的。当可燃气体中存在障碍物时，紊流是由诱导流动产生的。湍流会增加质量和能量的传递以及火焰锋面的面积，导致燃烧反应速率的增加，从而导致压力波的增强。所有这些提高燃烧速率的效果都取决于诱导流速，而诱导流速又取决于燃烧速率本身。这种关系能够形成一个正反馈系统。基于这一思想，我们发现即使在完全无约束的气体混合物中，当在火焰路径上重复放置梳状网格时，火焰的传播也很容易加速。在本研究中，我们研究了超高速爆燃的结构和向爆轰过渡的机理。它们是用高速照相机通过纹影取景或条纹照相来观察的。在光电池系统测量光发射的点上也观察到火焰的亮度。用压电式压力传感器测量瞬态压力波。我们使用的可燃气体是甲烷、乙烷或氢气与氧气的化学计量混合物，氧气被氮气、氩气或氦气稍微稀释。任何混合物的爆燃都可以通过重复的障碍物加速到任何速度。在障碍物或电网后面形成的大涡流消失后，可以观察到明显的火焰加速度。纹影相框照片中看到的加速火焰，看起来像细颗粒，比其他燃烧区域的湍流规模小得多。正如压力测量所观察到的那样，细小而强烈的湍流火焰产生爆炸波。火焰加速的机理并不取决于我们使用的混合物的种类。对于任何混合物，爆燃到爆轰的过渡确实发生，但甲烷混合物的爆轰开始延迟超过1000米/秒的火焰速度。爆燃速度极快，形成“激波+火焰”结构。少

项目成果

小川勇治・滝史郎: "メタン酸素混合気の開放空間中での火炎爆ごう遷移" 日本機械学会論文集(B編). 55. 1454-1457 (1989)

Yuji Okawa 和 Shiro Taki：“开放空间中甲烷-氧气混合物的火焰爆炸转变”日本机械工程师学会会刊（B 版）55。1454-1457（1989 年）。

Y. Ogawa and S. Taki: "Deflagration to Detonation in Methane/Oxygen Mixtures in Open Space" Transactions of The Japan Society of Mechanical Engineers. vol. B-55. 1454-1457 (1989)

Y. Okawa 和 S. Taki：“开放空间中甲烷/氧气混合物的爆燃到爆炸”日本机械工程师学会会刊。

Shiro,Taki: Progress in Astronautics Aeronautics. 114. 140-154 (1988)

Shiro，Taki：航天航空学的进展。

滝史郎: 日本機械学会論文集. (1989)

Shiro Taki：日本机械工程师学会会议记录（1989）。