Flame and Eddy Structures in Hydrogen-Air Turbulent Jet Premixed Flame
Flame and Eddy Structures in Hydrogen-Air Turbulent Jet Premixed Flame
复制标题
氢-空气湍流射流预混火焰中的火焰和涡流结构
DOI：
10.1080/14685248.2012.720022
复制
发表时间：
2012
影响因子：
1.9
通讯作者：
M. Tanahashi and T. Miyauchi
中科院分区：
文献类型：
--
作者：
M. Shimura;K. Yamawaki;N. Fukushima;Y.-S. Shim;Y. Nada;M. Tanahashi and T. Miyauchi
对射流平均流向速度为 100 m/s 和 350 m/s 两种情况进行了氢-空气湍流平面射流预混火焰的三维直接数值模拟 (DNS)，该火焰由未燃烧混合气体射流和周围已燃气体维持火焰组成。充分发展的均匀各向同性湍流叠加在平均流上。考虑了包括 12 个反应物种和 27 个基元反应的详细动力学机制。两种情况都会产生空间大尺度的涡流结构，而涡流形成的机制取决于入口速度。尽管当前 DNS 入口速度为 100 m/s 的燃烧状况被归类为波纹小火焰状态，但未燃烧的混合物岛经常出现在主火焰体后面。这些岛的形成与未燃烧气体中的细尺度涡流密切相关，分离的未燃烧混合物有助于放热速率和湍流燃烧速度的增加。统计研究了剪切强度和湍流强度对射流火焰放热速率和切向应变速率特性的影响。
Three-dimensional direct numerical simulation (DNS) of hydrogen–air turbulent plane jet premixed flames, which are composed of jet with unburnt mixture gas and surrounding burnt gas for flame holding, has been conducted for two cases of mean streamwise velocity of the jet, 100 m/s and 350 m/s. Fully-developed homogeneous isotropic turbulence is superimposed on the mean flow. A detailed kinetic mechanism including 12 reactive species and 27 elementary reactions is considered. Eddy structures which have large-scale in space are produced for both cases, whereas the mechanism of the eddy formation depends on the inlet velocity. Although combustion condition of the present DNS with inlet velocity 100 m/s is classified into corrugated flamelets regime, unburnt mixture islands frequently appear behind the main flame body. The creation of these islands is closely related to the fine-scale eddies in the unburnt gas and the separated unburnt mixture contributes to increase of heat release rate and turbulent burning velocity. Effects of shear and turbulent intensity on characteristics of heat release rate and tangential strain rate of the jet flames are investigated statistically.