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

超高速燃烧或超高强度燃烧可能有两种类型，即非常强烈的湍流火焰和爆轰。预混气体中的这两种气体都是由传播的火焰产生的。在可燃气体中存在障碍物时，湍流是由诱导流动产生的。湍流将增加质量和能量的传输和火焰前沿的面积，导致燃烧反应速度加快，从而导致压力波的增强。所有这些提高燃速的效果都取决于诱导气流速度，而诱导气流速度又取决于燃速本身。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，即使在完全开放的混合气体中，当梳状网格重复放置在火焰路径上时，火焰的传播也很容易被加速。在本研究中，我们研究了超高速爆燃和…的结构更多地研究了向爆轰转变的机制。它们是使用高速相机通过纹影相框或条纹照片观察到的。在通过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了瞬时压力波。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、氩或氦略微稀释。任何混合物的爆燃都可以被反复的障碍物加速到任何速度。在障碍物或栅格线后面形成的大漩涡消失后，可以观察到火焰的明显加速。纹影取景照片显示的加速火焰看起来像细小的颗粒，比其他燃烧区域的湍流尺度要小得多。通过压力测量观察到，细小而强烈的湍流火焰会产生冲击波。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，都会发生燃烧向爆轰的转变，但甲烷混合物的爆轰起始时间延迟到火焰速度1000m/S以上。极快的爆燃形成“激波+火焰”结构。较少

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）。