气相硼燃烧的化学动力学分析

Chemical Kinetics Analysis for Combustion of Gas-Phase Boron

关键词:  气相  硼  延迟时间  燃烧时间  化学动力学效应

Key words:  Gas-phase  Boron  Delay time  Combustion time  Chemical kinetic effect

摘要:

为研究温度和H2，CO，F等组分影响气相硼燃烧的化学反应动力学机制，利用基于CHEMKIN 建立的B/C/H/O/N/F体系的反应动力学机理，模拟了温度和各自由基摩尔分数随时间的变化，并通过敏感性分析和化学反应速率分析研究了不同条件下影响气相硼燃烧的主要基元反应。结果表明，影响气相硼燃烧的主要反应式是R31 BO+O+M=BO₂+M，BO的氧化速率决定了气相硼燃烧的快慢；提高初始温度，BO的氧化途径仍为R31；添加0.5% CO可以增加O自由基浓度，加快R31的反应速率；添加0.5% F后BO的氧化途径增加了反应式R183 BO+F+M=OBF+M，加快BO的氧化速率；添加0.5% H2后BO的氧化途径转变为R36 BO+H+M=HBO+M，R35 BO+OH+M=HBO₂+M和R58 BO₂+H+M=HBO₂+M，加快BO的氧化速率从而缩短延迟时间；在含有H2的初始组分中，气相硼燃烧的主导反应过程: B2O₂/HBO→BO→BO₂→HBO₂。

Abstract:

To study the chemical kinetics for effects of temperature and H2，CO，F free radicals on the combustion of gas-phase boron，the kinetic model and scheme of combustion in B/C/H/O/N/F systems based on CHEMKIN were presented. Evolution in time of temperature and mole fractions of free radicals were simulated，and key elementary reactions impacting on the combustion of gas-phase boron at different initial condition were found through sensitivity analysis and rate of BO analysis. The results show that，the important reaction for combustion of gas-phase boron is R31 BO+O+M=BO₂+M，the oxidation rate of BO is the key to control the rate of gas-phase boron combustion. The oxidized pathway of BO does not change with increasing of the initial temperature，the mole fraction of O free radical increases which makes reaction rate of R31 increase with adding 0.5% CO，the oxidized pathway of BO is changed to R31 and R183 BO+F+M=OBF+M for adding 0.5% F，and the oxidized pathway of BO is changed to R36 BO+H+M=HBO+M，R35 BO+OH+M=HBO₂+M，R58 BO₂+H+M=HBO₂+M for adding 0.5% H2 from R31 for auto-ignition，and thus they increase the oxidation rate of BO and reduce the delay time. The main reaction process for gas-phase boron with H2 is: B2O₂/HBO→BO→BO₂→HBO₂.