RP-3航空煤油高温骨架机理构建及验证

依据RP-3航空煤油的成分,考虑平均分子量及碳氢摩尔比等性质,本文提出其三组分替代燃料模型,其中正癸烷74.24%、1,3,5-三甲基环己烷14.11%和正丙基苯11.65%(质量分数)。采用机理生成程序ReaxGen得到详细化学反应机理;采用机理简化程序ReaxRed,运用直接关系图法与主成分分析法获得高温骨架机理(79物种,311反应)。该机理针对多个工况进行了点火延迟时间与层流火焰速度的验证,能较好地预测实验结果。路径分析结果表明高温下替代燃料通过氢提取反应、单分子裂解反应及β-断键反应消耗。敏感性分析表明高温点火过程由多种小分子自由基(H、CHO、C2H3等)的氧化及分解反应和大分子燃料的氢提取反应控制;影响火焰传播过程的关键反应来源于C0-C3的小分子核心机理。本文所提出的这个尺寸较小但精度较高的骨架机理可用于发动机燃烧过程的高保真数值模拟。

Development and validation of a skeletal mechanism for RP-3 aviation fuel at high temperatures

Based on the composition of RP-3 aviation kerosene fuel and consideration of both average molecular weight and hydrogen-carbon ratios,a three-component surrogate fuel was presented in this work,comprising 74.24%n-decane/14.11%1,3,5-trimethycyclohexane/11.65%n-propylbenzene(mass fraction).A detailed chemical kinetics mechanism was developed by the ReaxGen,an automatic mechanism generation program.Then a high-temperature skeletal mechanism involving 79 species and 311 reactions was developed by using ReaxRed,an automatic mechanism reduction program,employing both directed relation graph and principle components analysis.The simulations using the developed skeletal mechanism could capture the experimental data of ignition delay times and laminar flame speeds under various conditions.As flux analyses shown,the surrogate fuels were consumed via H-abstraction reactions,unimolecular dissociating reactions andβ-scission reactions at high temperatures.As sensitivity analyses shown,the ignition process under high temperatures was controlled by oxidation and dissociation reactions related to small radicals(H,CHO,C2H3,et al.),and H-abstraction reactions related to large hydrocarbons.The key reactions influencing the laminar flames propagation process stemmed from the sub-mechanism of C0-C3.This skeletal mechanism can be applied to numerical simulations for combustion process of engines.