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Studies on Micro Structure and Dynamic Behavior of Stretch-Controlled Flames

拉伸控制火焰的微观结构和动态行为研究

基本信息

批准号：
17560195
负责人：
TAKAGI Toshimi
金额：
$ 2.35万
依托单位：
Osaka Sangyo University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
2005
资助国家：
日本
起止时间：
2005 至 2007
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-17560195/
关键词：
Diffusion flames Premixed flames Spherical flames Stretch rate Burning velocity Extinction Hydrogen and methane Numerical computation 平面予混合火炎燃焼率平面拡散火炎消炎局所性対流の影響

项目摘要

Numerical computations of laminar flames have been conducted taking into account detailed chemical kinetics and multi-component diffusion. Diffusion flames, flat premixed flames and spherical flames considered of different stretch rate.In the diffusion flames, (1) There are two types of extinction, the intermittent and the perfect extinction. (2) Extinction occurs slightly in down stream where local stretch rate is the largest. (3) The local stretch rate is much affect the extinction. (4) The convection flow along the flamelet changes the extinction limit.In the flat premixed flame, (1) Symmetrical twin flame is formed As the counter velocity increases, the peak of the heat release rate comes to the central part. (2) The burning velocity increases with increasing the stretch rate, but the burning rate decreases with increasing the stretch rate.The effects of the stretch rate are investigated on the burning velocity in three kind of hydrogen/air flames, that is, outwardly propagating (OPF), inwardly propagating (IPF) and stationary (SF) spherical Direction of the flame propagation and radius of the flame change the stretch rate.(1) The burning velocity is changed for the smaller radius than 5mm. For the IPF, the flame velocity becomes large for the equivalence ratio ¢ larger than 0.7. But, for the smaller Φ, the results is opposite. The change is opposite for the OPF and IPF. (2) The stretch rate of the SF is zero, but the burning velocity has a wide range. (3) The burning velocity is dominated by not only the stretch rate but also the Lewis number, because the burning velocity has the opposite results assuming different diffusivities.

层流火焰的数值计算已进行考虑到详细的化学动力学和多组分扩散。扩散火焰、平板预混火焰和球形火焰在不同拉伸率下的熄灭情况：（1）扩散火焰的熄灭有间歇熄灭和完全熄灭两种类型。(2)在局部拉伸率最大的下游，发生轻微的灭绝。(3)局部拉伸率对消光系数影响很大。(4)在扁平预混火焰中，（1）形成对称的孪生火焰，随着对流速度的增加，热释放率的峰值出现在火焰中心; (2)研究了拉伸率对氢气/空气球形火焰（OPF、IPF和SF）燃烧速度的影响，分析了拉伸率对氢气/空气球形火焰燃烧速度的影响规律。(1)在小于5 mm的半径范围内改变燃烧速度。对于IPF，当当量比大于0.7时，火焰速度变大。但是，对于较小的Φ，结果是相反的。OPF和IPF的变化相反。(2)SF的拉伸率为零，但燃烧速度有一个宽的范围。(3)燃烧速度不仅受拉伸率的影响，而且受刘易斯数的影响，因为假设不同的扩散系数，燃烧速度有相反的结果。