预燃室氢射流火焰引燃氨预混气火焰发展及着火特性数值研究

Numerical Investigation on the Flame Development and Ignition Characteristics of Ammonia Premixed Gas Ignited by Hydrogen Jet Flame in A Pre-Chamber

基于计算流体平台CONVERGE,对化学当量比下H_(2)射流火焰引燃NH_(3)、空气预混气过程中射流火焰的发展历程、射流特性及主/预燃室物质场分布进行了数值仿真。结果表明:射流火焰发展历程可分为射流阶段、过渡阶段和热射流阶段三个阶段;射流火焰的前锋面移动距离的增长率受NH_(3)火焰传播速度的制约而逐渐下降;随着射流引燃的进行,射流火焰温度场和物质浓度场呈现明显分层现象,NH_(2)高浓度区经分离后分布在射流头部的NH_(3)燃烧区及射流尾部的H_(2)射流火焰区。

Based on the computational fluid platform CONVERGE,the development process of jet flame,jet characteristics and the distribution of species concentration were investigated in the process of ammonia ignition by hydrogen jet flame.The results show that the development process of jet flame can be divided into three stages,i.e.,cold jet stage,transition stage and hot jet stage.The growth rate of the flame front distance of the ignition jet flame gradually decreases due to the restriction of the NH_(3) flame propagation speed.With the progress of jet ignition,the temperature field and matter field of jet flame show obvious stratification.The high concentration area of NH_(2) is distributed in the NH_(3) combustion area of jet head and the H_(2) jet flame area of jet tail after NH_(2) separation.