摘要
为研究缩比火箭发动机尾焰等离子体特性,分析尾焰弱电离气体流场结构与电磁特性的相关性,基于被动自发光谱与朗缪尔探针开展试验研究,重点给出缩比火箭发动机紫外到近红外波段自发光谱,尾焰离子、电子密度和电导率的时域、频域以及空间概率分布特性。被动自发光谱试验结果表明火箭发动机尾焰流场自发辐射光谱存在588nm、619nm、669nm、765nm的光谱特征峰,分别对应Na、Fe、Al、C元素。其中碱金属Na、Fe、Al元素对电导率有突出贡献,Na元素主要来自于大气中的含盐组分,Fe和Al碱金属元素可能来源于推进剂燃烧或者合金结构材料;朗缪尔双探针和三探针试验结果表明,朗缪尔双探针测量电导率与计算电导率数量级相同,约为10-4~10-3S/m,朗缪尔三探针测量电导率低于计算电导率数量级,约为10^(-5)~10^(-4)S/m;沿发动机轴向,两种探针的电导率均呈指数规律衰减且离子密度概率密度空间分布存在显著差异;探针电流频谱存在50Hz低频主峰和2000Hz、20000Hz高频主峰。
To study the plasma characteristics of a scaled-down rocket engine plume and elucidate the weakly ionized gas flow field structure and electromagnetic properties,experiments based on a passive emission spectroscopy and Langmuir probes are documented.The chemiluminescence of the scaled rocket engine,the plume ion and electron density,and electrical conductivity are characterized.The results of passive emission spectroscopy experiments indicate that the typical wavelength of 588 nm,619 nm,669 nm and 765 nm are observed corresponding to the element of Na,Fe,Al and C.The element of Na,Fe and Al significantly induce free electron and the electrical conductivity of the rocket plume.The double probe Langmuir measurements of electrical conductivity are in the order of 10^(-4) to 10^(-3) S/m,while the triple-probe Langmuir measurements suggests lower electrical conductivity levels,ranging from approximately 10^(-5) to 10^(-4) S/m.Along the axial direction of the engine,exponential decay in the electrical conductivity has been observed.Additionally,the probe current spectra exhibited prominent peaks at low frequencies around 50 Hz and high frequencies at 2000 Hz and 20000 Hz.Efforts should address the effect of the flow structure in these scales.
作者
李心阳
王大锐
任牧原
王业军
连欢
LI Xinyang;WANG Darui;REN Muyuan;WANG Yejun;LIAN Huan(State Key Laborotory of High Temperature Gas Dynamics,Insitute of Mechanics,Chinese Academy of Sciences,Beijing,100190;University of Chinese Academy of Sciences,Beijing,100190;Beijing Institute of Aerospace Engineering Systems,Beijing,100076)
关键词
尾焰等离子体特性
尾焰流场
朗缪尔探针
电导率
频域分析
plume plasma characteristics
plume flow dynamics
Langmuir probe
electrical conductivity
frequency domain analysis
