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首页> 外文期刊>Journal of Spacecraft and Rockets >Uncertainty Analysis of Air Radiation for Lunar-Return Shock Layers
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Uncertainty Analysis of Air Radiation for Lunar-Return Shock Layers

机译：月球回波冲击层空气辐射的不确定度分析

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摘要

By leveraging a new uncertainty markup technique, two risk analysis methods are used to compute the uncertainty of lunar-return shock-layer radiation predicted by the High-temperature Aerothermodynamic Radiation Algorithm (HARA). The effects of epistemic uncertainty, or uncertainty due to a lack of knowledge, are considered for the following modeling parameters: atomic-line oscillator strengths, atomic-line Stark broadening widths, atomic photoionization cross sections, negative-ion photodetachment cross sections, molecular-band oscillator strengths, and electron-impact excitation rates. First, a simplified shock-layer problem consisting of two constant-property equilibrium layers is considered. The results of this simplified problem show that the atomic-nitrogen oscillator strengths and Stark broadening widths in both the vacuum ultraviolet and infrared spectral regions, along with the negative-ion continuum, are the dominant uncertainty contributors. Next, three variable-property stagnation-line shock-layer cases are analyzed: a typical lunar-return case and two Fire II entry-vehicle cases. For the near-equilibrium lunar-return and Fire 1643 s cases, the resulting uncertainties are similar to the simplified case. Conversely, the relatively nonequilibrium 1636 s case shows significantly larger influence from electron-impact excitation rates of both atoms and molecules. For all cases, the total uncertainty in radiative heat flux to the wall due to epistemic uncertainty in modeling parameters is ±30% as opposed to the erroneously small uncertainty levels (±6%) found when treating model parameter uncertainties as aleatory (due to chance) instead of epistemic (due to lack of knowledge).
机译：通过利用一种新的不确定性标记技术，使用了两种风险分析方法来计算由高温空气热力学辐射算法（HARA）预测的月球返回冲击层辐射的不确定性。对于以下建模参数，考虑了认知不确定性或因缺乏知识而导致的不确定性的影响：原子线振荡器强度，原子线斯塔克展宽宽度，原子光电离截面，负离子光解离截面，分子带振荡器的强度和电子冲击激发速率。首先，考虑了一个简化的冲击层问题，该问题由两个恒定性质的平衡层组成。这个简化问题的结果表明，真空紫外和红外光谱区域中的原子氮振荡器强度和Stark加宽宽度，以及负离子连续体，都是造成不确定性的主要因素。接下来，分析了三个变性质停滞线冲击层情况：一个典型的月球返回情况和两个Fire II进入车辆情况。对于接近平衡的月球返回和1643年代火灾，所产生的不确定性与简化情况相似。相反，相对非平衡的1636 s情况显示了原子和分子的电子碰撞激发速率的显着更大影响。在所有情况下，由于模型参数中的认知不确定性，壁的辐射热通量的总不确定性为±30％，而将模型参数不确定性视为偶然的（由于偶然性）则发现错误的较小不确定性水平（±6％） ）而不是认知知识（由于缺乏知识）。

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