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气流温度和组分粒子数密度是定量评估电弧加热器运行参数和流场品质的关键,常规测试手段难以适应电弧加热器内高温气流的恶劣环境,电弧加热器等离子体气流诊断研究一直缺乏有效手段。本研究应用激光吸收光谱技术,选用原子O(777.19nm)谱线,基于局部热化学平衡等离子体假设,对电弧加热器内高温离解空气(>5000K)试验气流进行在线诊断。试验测得了总焓H0=15.8,17.4MJ/kg 2组工况下,电弧加热器内等离子体气流温度和原子O粒子数密度。2组工况获得平均气流温度分别为5843和6047K,对应高温平衡气流表获得气流温度为5950和6335K。测得加热器运行稳定后2组工况的原子O总粒子数密度在(1.1~1.2)×1018cm-3之间,低能级5S02粒子数密度在(1.0~1.6)×1010cm-3之间,2组工况原子O总粒子数密度的差异与NASA-CEA平衡计算结果一致,验证了电弧加热器气流局部热力学平衡假设的有效性。本研究工作验证了激光吸收光谱技术可作为高焓电弧加热器常规诊断手段。
Air temperature and particle number density are the keys to quantitatively evaluate arc heater operating parameters and flow field quality. Conventional test methods are difficult to adapt to the harsh environment of high temperature gas flow in arc heaters. There is a lack of effective means to diagnose the plasma gas flow of arc heater . In this study, laser absorption spectroscopy was used to diagnose the gas flow of high temperature dissociation air (> 5000K) in the arc heater based on the assumption of local thermochemical equilibrium plasma using atomic O (777.19 nm) spectrum. The experiment measured the total enthalpy H0 = 15.8,17.4MJ / kg 2 group conditions, the arc heater plasma gas flow temperature and atomic number density of O particles. The average airflow temperatures of the two groups were 5843 and 6047K respectively, corresponding to the high temperature equilibrium airflow table, the airflow temperatures were 5950 and 6335K. The total number density of atomic O particles in the two working conditions was between 1.1 and 1.2 × 10 18 cm-3 and the number density of low-energy 5 SO 2 particles was in the range of 1.0 to 1.6 × 1010 cm-3. The difference of the total number density of atom O in the two groups of working condition is consistent with the NASA-CEA equilibrium calculation, which verifies the validity of the local thermodynamic equilibrium assumption of arc heater airflow. This work verifies that laser absorption spectroscopy can be used as a routine diagnostic tool for high enthalpy arc heaters.