Cratering of a Lunar Soil Simulant, JSC-1A, by a Turbulent Subsonic Jet
Cratering of a Lunar Soil Simulant, JSC-1A, by a Turbulent Subsonic Jet
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亚音速湍流射流造成月球土壤模拟物 JSC-1A 的陨石坑
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发表时间：
2012
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通讯作者：
P. Metzger
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作者：
C. Lamarche;J. Curtis;P. Metzger
从航天器撞击的火箭羽流与月球表面的风化层相互作用，并释放出高速粒子喷雾，这对周围的表面结构和表面建筑具有潜在的危险。在美国宇航局-韩国航天中心和佛罗里达大学进行的实验提供了由月壤模拟物JSC-1A组成的颗粒床被湍流亚音速气体射流撞击成坑的数据。还对粒径分布比JSC-1A窄的海滩砂进行了成坑实验。JSC-1A包含宽粒度分布和大量细颗粒（20%体积小于35 μm）。JSC-1A是高度可压缩的，并且比海滩砂包含更粗糙和更多角颗粒。JSC-1A和海滩砂之间颗粒特性的差异导致两种材料的撞击坑明显不同。海滩砂的撞击坑形成了由圆锥形外撞击坑和抛物面形内撞击坑组成的双重撞击坑形状。当射流撞击在沙子上时，弹坑随着时间的推移而几何地增长，并且当颗粒从内弹坑喷射到外弹坑上时，外弹坑在休止角和失效角之间循环。JSC-1A陨石坑的形状类似于冲刷坑，随着时间的推移越来越深，大块的材料被射流侵蚀。JSC-1A弹坑的增长率高度依赖于JSC-1A的堆积床密度。对于相同的射流速度，具有较高堆积密度（更紧凑）的JSC-1A床的成坑速率比具有较低堆积密度（不太紧凑）的床慢。即使对于较低的射流速度，不太紧凑的床可以比更紧凑的床更快地形成凹坑。通过筛分至150至425 μm的粒度范围，研究了JSC-1A筛分部分在不存在细颗粒的情况下的缩孔。筛分的JSC-1A的弹坑更类似于海滩砂的弹坑，而不是未筛分的JSC-1A，这表明未筛分的JSC-1A中细颗粒的存在是其非典型弹坑行为的原因。36地球与空间© ASCE 2012
Impinging rocket plumes from spacecraft interact with the lunar regolith surface and release a high velocity particle-spray that is potentially hazardous to surrounding surface structures and surface architecture. Experiments performed at NASA-KSC and the University of Florida provide data on the cratering of a particle bed composed of lunar soil simulant JSC-1A by a turbulent subsonic jet of gas. Cratering experiments were also performed on beach sand, which has a narrower particle size distribution than JSC-1A. JSC-1A contains a wide particle size distribution with a high number of fine particles (20% by volume less than 35 μm). JSC-1A is highly compressible and contains much rougher and more angular particles than beach sand. The differences in the particle properties between JSC-1A and beach sand leads to stark differences in the cratering of the two materials. The cratering of beach sand results in a dual crater shape consisting of a conical outer crater and a paraboloid inner crater. While the jet is impinging on the sand, the crater grows logarithmically with time and the outer crater cycles between the angle of repose and angle of failure as particles are ejected from the inner crater onto the outer crater. The JSC-1A crater is similar to a scour hole in shape, which grows deeper over time, with large chunks of material being eroded by the jet. The growth rate of the crater of JSC-1A is highly dependent on the bulk bed density of the JSC-1A. For the same jet velocity the cratering rate of a bed of JSC-1A with a higher bulk density (more compact) was slower than a bed with a lower bulk density (less compact). Even for a lower jet velocity, the less compact bed can crater faster than the more compact bed. The cratering of a sieved fraction of JSC-1A in the absence of fine particles is studied by sieving to a particle size range of 150 to 425 μm. The cratering of sieved JSC-1A is more similar to the cratering of beach sand than to unsieved JSC-1A indicating that the presence of fine particles in unsieved JSC-1A is the cause for its atypical cratering behavior. 36 Earth and Space 2012 © ASCE 2012