高焓电弧风洞等离子体参数测量

Measurement of Plasma Parameters in High-Enthalpy Arc-Heated Wind Tunnel

  • 摘要: 地面试验是开展等离子体流场特性表征的重要手段,本文针对高焓流场等离子体参数辨识的需求,在电弧风洞开展了典型流场等离子体参数测量研究。利用带攻角钝楔平板模型模拟飞行器大面积区流场,采用静电探针诊断技术,结合电动扫描技术进行了钝楔模型流场电子密度的空间分布测量,同时使用数值方法开展了对应状态的仿真模拟,两者进行了对比验证。研究发现:对于当前风洞条件,矩形喷管Z向80 mm厚度核心区的等离子体参数基本保持均匀稳定,在靠近喷管壁面的两侧边缘位置受边界层影响电子密度明显衰减。本文所采用的探针测量方案对于电子密度测试的影响较小:对于相对高电子密度(1011 cm–3)工况电子密度实测值与计算值吻合良好,偏差小于0.5个数量级;低电子密度(1010 cm–3)工况等离子体电子密度实测值显著高于计算值,偏差在0.5~1个量级,初步分析是电极烧蚀带来的铜污染效应是重要的影响因素。

     

    Abstract: Ground-based testing serves as a crucial approach for characterizing the properties of plasma flow fields. In response to the need for plasma parameter identification in high-enthalpy flows, this study conducted experimental investigations of typical plasma parameters in an arc-heated wind tunnel. A blunt wedge flat-plate model with an angle of attack was employed to simulate the flow over large-area regions of a spacecraft. Spatial distributions of electron density in the model's flow field were measured using electrostatic probe diagnostics in conjunction with an electrically actuated scanning mechanism. In parallel, numerical simulations were performed under equivalent conditions, and the experimental and computational results were compared for validation. The results indicate that, under the current wind tunnel conditions, the plasma parameters within the 80 mm thick core region along the Z-direction of the rectangular nozzle remain generally uniform and stable. However, near the nozzle walls, the electron density shows significant attenuation due to boundary layer effects. The probe measurement scheme adopted in this study exerts minimal influence on electron density measurements. For conditions with relatively high electron density (~1011 cm3), the experimental values closely match the simulation results, with deviations less than 0.5 orders of magnitude. In contrast, under low electron density conditions (~1010 cm3), the measured electron densities are substantially higher than the simulated values, with deviations between 0.5 and 1 order of magnitude. Preliminary analysis suggests that copper contamination resulting from electrode ablation is a significant contributing factor.

     

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