CO与H_(2)氧化释热对煤油V型钝体稳焰器回流特性的影响

Effects of CO and H_(2) Oxidation Heat Release on Reversed-Flow Characteristics of Kerosene V-Gutter Bluff Body Flameholder

针对高速、贫氧的加力燃烧室流动特性,应用大涡模拟-输运概率密度函数方法(LES-TPDF)结合三种航空煤油机理,在来流马赫数为0.1的条件下,对一种V型钝体稳焰器进行两相燃烧流场的计算。结果表明,不同化学机理模拟的回流特性差异大,剪切层湍动能强度与回流区长度不同。由释热分析发现,钝体燃烧CO或H_(2)氧化强烈,过弱的氧化使剪切层释热率低、掺混弱,因此湍动能小,CO和H_(2)在回流区积累并缓慢反应、延长回流。本文统计不同机理的反应放热量,发现Kundu机理的CO,H_(2)氧化放热之和仅占总过程的25.30%。而反应强的骨架机理与JL4机理放热占比达到50.50%与87.16%,回流吻合实验,适用于当前工况的研究。

Aiming at the flow characteristics in the high-speed,low-oxygen afterburner combustion chamber,three chemical mechanisms with Large Eddy Simulation and Transport Probability Density Function(LESTPDF)method were selected to calculate the two phase combustion flow field of a V-gutter flameholder with an inflow Mach number of 0.1.Results show that reversed-flow characteristics vary between different chemical mechanisms,making turbulent kinetic energy and recirculation zone length different.The analysis of heat release characteristics reveals that CO or H_(2)are vigorously oxidized in bluff-body combustion.Too weak oxidation leads to low heat release rate at shear layer and weak mixing,hence a low turbulent kinetic energy and accumulating excess CO and Hin the recirculation zone,which reacts mildly and prolongs reversed-flow.The reaction exothermic is also analyzed in this paper and it is found that,for the Kundu mechanism,CO and H_(2)oxidation exotherm only accounts for 25.30%of the overall process.While the skeleton mechanism and JL4 mechanism,with higher oxidation exotherm,account for 50.50%and 87.16%,which match experimental flow characteristics and are suitable for the study of the current condition.