HAN基液体推进剂单滴无弧点火过程的数值模拟

Numerical Simulation for Arcless Electrical Ignition Process of Single Droplet of HAN-based Liquid Propellant

为研究硝酸羟胺（HAN）基单元液体推进剂LP1846单滴无弧电点火的机理,基于两步不可逆化学反应机理,同时考虑物性参数随温度的变化关系,结合相关实验,对HAN基液体推进剂LP1846液滴在大气环境下的无弧电点火过程进行了数值模拟。结果表明：根据化学反应速率和温度分布变化,将最大加载电压80 V的无弧点电火过程分为预热（0~695 ms）、热分解（695~805 ms）及燃烧（805~1000 ms）三个特征阶段。预热阶段,液滴保持球形,中心温度缓慢上升;热分解阶段,反应在液滴中心产生向外发展,液滴膨胀变大,内部出现伞形温度梯度分布;燃烧阶段,火焰在液滴内部生成,LP1846剧烈燃烧生成大量产物,流场温度先升后降。液滴着火延迟期随着最大加载电压的增大而减小,模拟结果与实验数据变化趋势一致,最大误差为2.9%。

T o study the arcless electrical ignition mechanism of hydroxylammonium nitrate（ HAN）-based liquid monopropellant LP1846droplet,based on the tw o step irreversible chemical reaction mechanism,at the same time,considering the changes of physical parameters w ith temperature,the numerical simulation for the arcless electrical ignition process of single HAN-based liquid monopropellant LP1846 droplet w as performed in the atmospheric environment combined w ith the related experiments. R esults indicate that,according to the variation of reaction rate and temperature distribution,w hen maximum load voltage is 80 V,the arcless electrical ignition process can be divided into three feature stages： preheating（ 0 ~ 695 ms）,thermal decomposition（ 695 ~ 805 ms） and combustion（ 805 ~ 1000 ms）. At the preheating stage,the droplet is spherical and the center temperature rises slow ly. At the thermal decomposition stage,the reaction occurs in the center of the droplet and develops outw ards,the droplet expands and the umbrella distribution of temperature gradient appears inside the droplet. At the combustion stage,the flame is spaw ned inside the droplet. LP1846 burns vigorously,forming a large amount of products. T he temperature of the flow field first increases and then decreases. Ignition delay time decreases w ith the increase of maximum load voltage. T he simulated results has the same trendline of change w ith the experiment data,and the maximum error is 2. 9%.