铝颗粒群点火与燃烧特性研究

Investigation on Ignition and Combustion of Aluminum Suspension

面向固体火箭发动机和粉末冲压发动机中铝粉颗粒群在高温和氧化性环境的燃烧机理,开展微米级铝颗粒群点火与燃烧特性实验研究和理论分析。建立了甲烷平面火焰燃烧系统提供温度和组分可控的均匀高温环境,通过振荡式气溶胶发生装置产生由氮气携带的局部高浓度铝粉脉冲射流在高温环境中进行点火和燃烧,发展了基于发射光谱和比色法的测温技术,同时运用高速显微摄影进行测量。研究结果表明铝颗粒群的着火温度低于单个铝颗粒,颗粒群燃烧温度接近3000 K,实验中观测到了颗粒群边界处铝蒸气燃烧的气相火焰面,说明铝颗粒间的聚集效应对铝粉点火和燃烧过程有重要影响。

Focusing on the combustion mechanism of aluminum powder suspensions athigh temperatures and oxidative environments in solid rocket motors or powderedfuel engines,this work conducted experimental research and theoretical analysis of the ignition and combustion characteristics of micron-sized aluminum suspensions.A methane flat-flame burner is employed to provide quasi-uniform high-temperature exhaust with controllable temperature and gas compositions,and an oscillating aerosol generator is used to produce a local high-concentration aluminum powder pulsed jet carried by nitrogen for ignition and combustion in the hot exhaust.Meanwhile,the emissions spectra diagnostic and colorimetric thermometry techniques are developed to measure the particle temperature,while high-speed photomicrography is utilized to visualize flame structures.The research results show that the ignition temperature of the aluminum particle suspension is much lower than that of a single aluminum particle,and the combustion temperature of the particle suspension is close to 3000 K.In the experiment,the gas-phase flame front of aluminum vapor combustion is observed at the boundary of the suspension,indicating that the collective effect has an impact on the ignition and combustion of aluminum particle suspensions.