基于KMC方法的离解氧原子在硅基防热材料表面催化复合模型研究
Catalytic Recombination Model of Dissociated Oxygen Atoms on Silica-Based Thermal Protection Material Based on KMC Method
李芹 1杨肖峰 2董威 3杜雁霞2
作者信息
- 1. 上海交通大学机械与动力工程学院,上海 200240;中国空气动力研究与发展中心空气动力学国家重点实验室,绵阳 621000
- 2. 中国空气动力研究与发展中心空气动力学国家重点实验室,绵阳 621000
- 3. 上海交通大学机械与动力工程学院,上海 200240
- 折叠
摘要
为了精确模拟化学非平衡气流在高速飞行器表面的多相催化反应过程,进而提高气动热的预测精度,基于反应动力学机理和硅基材料表面的微观物性参数,发展了一种用于模拟多步催化反应过程的运动学蒙特卡罗(KMC)模型,用于求解高焓离解气体在硅基材料表面的复合速率.模型将吸附、ER/LH复合、热解附四种微观反应过程考虑在内,并从碰撞频率和反应系数两个角度给出各反应的相对概率,作为KMC随机选取下一反应发生的依据.采用该模型计算的表面反应结果表明,LH复合反应具有明显的空间效应,该效应在高壁面温度条件下更明显,导致KMC模型预测的氧原子覆盖率低于基于均匀吸附表面假设的宏观模型的结果,且壁面温度越高相差越大.此外,研究发现ER和LH复合反应速率均随壁面温度的升高先增加后减小.KMC模型可以为宏观CFD计算提供更精确的催化壁面边界条件,用于气动热的精细化预测,为飞行器热防护系统的设计提供理论支撑.
Abstract
To simulate heterogeneous catalysis reaction process of chemical non-equilibrium gas on surface of hypersonic aircraft,further improve the prediction accuracy of aerodynamic heat-ing,a kinetic Monte Carlo(KMC)model for multi-step reaction of heterogeneous catalysis was developed based on the chemical kinetics mechanism and property parameters of silica-based mate-rial.Surface adsorption,ER/LH recombination and thermal desorption were involved in the model.KMC method selects the next reaction step according to the frequency of collision and probabil-ity of reaction.Reaction results based on the catalytic model showed that LH recombination was accompanied by spatial effects,which was more significant at higher wall temperatures.Because the spatial effect,coverage of atomic oxygen predicted by the KMC model was lower than that by model based on the assumption of mean-field adsorption,which was also more significant at higher wall temperatures.Moreover,both recombination coefficients of ER and LH mechanism first increase and then decrease with the increase of wall temperature.KMC model could pro-vide accurate catalytic boundary condition for the macroscale CFD prediction of aerodynamic heat-ing.Furthermore,it provides theoretical support for the design of thermal protection system of aircraft.
关键词
气动热/多相催化/界面物理/运动学蒙特卡罗方法Key words
aerodynamic heating/heterogeneous catalysis/interface physics/kinetic Monte Carlo method引用本文复制引用
基金项目
国家重点研发计划(2019YFA0405202)
国家自然科学基金(12072361)
出版年
2024
NETL
NSTL
维普
万方数据