液体火箭发动机尾焰金属发射光谱仿真与实验研究

Numerical and experimental investigations of metal emission spectrum in liquid rocket engine plume

关键词:  液体火箭发动机  原子发射光谱  数值模拟  光学厚度  逐线法

Key words:  Liquid rocket engine  Atomic emission spectra  Numerical simulation  Optical thickness  Line-by-line

摘要:

液体火箭发动机尾焰包含丰富的光谱信息，可以作为检测发动机运行状态与故障情况的重要依据。本文建立了高精度的液体火箭发动机尾焰金属发射光谱数值模拟方法，该方法以逐线法（Line-by-Line，LBL）为基础，考虑介质的光学厚度影响。利用该方法，对液体火箭发动机发生故障时，尾焰中可能存在的铁、镍、钾发射光谱进行了数值模拟，模拟结果与NASA光谱模拟程序所得结果相吻合。最后，在甲烷-氧气、乙烯-氧气预混火焰开展了铁、钾发射光谱的实验验证，结果表明，以光谱面积与特征峰强度为对比参数，光谱模拟结果和实验结果的相对误差在2.5%以下，利用实验数据，进一步讨论了光学薄和光学厚两种模型的适用性。

Abstract:

The plume of liquid rocket engine contains abundant spectrum information， which can be used to infer the operating and fault conditions of the engine. A high-accuracy numerical method has been established in this paper for the simulations of metal emission spectrum in the plume of liquid rocket engine. The method was based on the line-by-line （LBL） spectrum simulating scheme， and considered the effects of the medium optical thickness. Based on the method， the emission spectrums of iron， nickel， and potassium in the plume were simulated when engine failures occurred. The results agreed well with those obtained by the NASA plume simulation code. Besides， experimental verifications of emission spectra of iron and potassium were performed on CH₄/O₂ and C₂H₄/O₂ flames. Results show that the differences of spectrum area and characteristic spectrum peak intensity between simulated and experimental data were below to 2.5%. Last， the capability and limit of optical thin and thick models were evaluated.