HCCI工况下氨氢混合物燃烧的直接数值模拟

Direct Numerical Simulation of Ammonia-Hydrogen Mixture CombustionUnder HCCI Conditions

本文利用直接数值模拟方法对均质压燃(HCCI, Homogeneous Charge Compression Ignition)工况下氨氢混合物的着火和燃烧特性进行了研究。结果表明,着火首先从局部孤立区域处发生,随后发展到整个计算区域;最高燃烧温度和热释率随着掺氢比的增加而增加;通过与零维计算结果对比,发现湍流和热分层使得氨氢混合物着火提前。利用直接数值模拟数据计算了反应锋面的位移速度,并据此分析了自着火和火焰传播这两种燃烧模式。发现在低掺氢比的情况下,燃烧模式以自着火为主;而在高掺氢比的情况下,燃烧模式以火焰传播为主。

In this paper,direct numerical simulations of ammonia-hydrogen mixture combustion under Homogeneous Charge Compression Ignition(HCCI)conditions were performed to study the ignition and combustion characteristics.The results show that the ignition occurs in isolated regions at first and then develops to the entire domain.The maximum combustion temperature and heat release rate increase with increasing hydrogen addition ratio.By comparing with zero-dimensional calculation results,it was found that turbulence and thermal stratification facilitate the ignition process.The displacement speed of the reaction front was calculated using the direct numerical simulation data,and two combustion modes,auto-ignition and flame propagation,were analyzed.It was found that auto-ignition is the dominant combustion mode for the cases with low hydrogen addition ratio while flame propagation is the dominant combustion mode for the cases with high hydrogen addition ratio.