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电弧加热器试验条件下铁质小行星材料烧蚀机理分析

Analysis of Ablation Mechanism of Iron Asteroid Materials Under the Condition of Arc Heater Test

  • 摘要: 研究铁质小行星进入地球大气层的烧蚀机理,对评估小行星撞击地球危害具有重要意义。基于试验现象建立了铁质小行星材料烧蚀的熔融烧蚀和熔融层剪切烧蚀模型,采用具有移动边界的气动热、烧蚀与内部热传导耦合求解技术对铁陨石模型烧蚀试验状态进行了计算。计算分析表明建立的剪切烧蚀模型能够得到与试验在定性上一致的驻点烧蚀速率变化规律。若不考虑液态层流失,计算得到的规律与试验相反。计算分析结果显示表面蒸发速率与熔融层质量流失速率相比是小量,表明铁质小行星烧蚀以熔融层剪切流失为主导。可为小行星撞击地球防御提供参考。

     

    Abstract: When the asteroid enters earth’s atmosphere at a very high speed, the surface temperature rises and the surface material melts and loses under the severe aerodynamic heat. Studying the ablation mechanism of iron asteroids entering the Earth’s atmosphere is of great significance to study the ablation mechanism of iron asteroids entering the Earth’s atmosphere to evaluate the impact of such asteroids on the earth. In 2021, the Hypervelocity Aerodynamics Institute of China Aerodynamics Research and Development Center carried out the ablation test of the spherical cone-shaped iron meteorite model(head radius 20 mm, half cone angle 9 degrees)on the arc heater. The tested simulated state is that the stagnation heat flux is 13.9~19.5 MW/m2 and the stagnation pressure is 0.51~0.28 MPa. In this paper, based on the experimental phenomenon, the melting ablation model and the melting layer shear ablation model of iron asteroid material ablation are established. and the ablation test state of meteorite model is calculated by using the coupled solution methodology of aerodynamic heat, ablation and internal heat conduction with moving boundary. The calculation and analysis show that the shear ablation model established in this paper can obtain qualitatively consistent stagnation point ablation rate. If the loss of liquid layer is not considered, the calculated law is contrary to the experiment. The calculation shows that the surface evaporation rate is small compared with the mass loss rate of molten layer, which indicates that the ablation of iron asteroids is dominated by the shear loss of molten layer. It can provide reference for asteroid impact Earth defense.

     

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