Abstract The present experimental study investigates the shear stripping breakup of single droplets in subsonic and supersonic gaseous flows. In contrast to most research that places emphasis on the Weber number (We), we focus on the individual effects exerted by flow Mach (M∞) and Reynolds numbers (Re). Millimeter-sized droplets made of either ethylene glycol or water are exposed to shock-induced flows. Shadowgraph and schlieren images of the breakup process are recorded by an ultra-high-speed camera. The experimental We is constrained at 1100, while M∞ is varied from 0.3 to 1.19 and Re from 2600 to 24,000. A systematic analysis of the experiment series reveals that the breakup pattern alters with M∞ although a constant We is maintained. The classical stripping behavior with fine mist shed from the peripheral sheet changes to rupture of multiple bags along the periphery at M∞ = 0.63, and further to stretching of ligament structures from the leeward surface at M∞ = 1.19. The corresponding breakup initiation is delayed and the resultant fragments are sized less uniformly and distributed over a narrower spread. In terms of the early-stage deformation, droplets experience less intense flattening and slower sheet growth at higher M∞. The change of Re introduces additional variations, but only to a minor extent. Graphical abstract

中文翻译：

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马赫数对剪切剥离状态下液滴气动破碎的影响

摘要 本实验研究研究了亚音速和超音速气流中单个液滴的剪切剥离破裂。与大多数强调韦伯数 (We) 的研究相比，我们关注的是流动马赫数 (M∞) 和雷诺数 (Re) 所产生的个体效应。由乙二醇或水制成的毫米大小的液滴暴露在冲击引起的流动中。分裂过程的阴影图和纹影图像由超高速相机记录。实验 We 被限制在 1100，而 M∞ 从 0.3 变化到 1.19，Re 从 2600 变化到 24,000。对实验系列的系统分析表明，尽管维持恒定的 We，但分裂模式会随着 M∞ 的变化而变化。在 M∞ = 0.63 时，带有细雾从外围板脱落的经典剥离行为变为沿外围的多个袋子破裂，并进一步在 M∞ = 1.19 时从背风面拉伸韧带结构。相应的破碎起始被延迟，并且所得碎片的尺寸不太均匀并且分布在更窄的范围内。就早期变形而言，液滴在较高的 M∞ 下经历较不强烈的扁平化和较慢的片材生长。Re 的变化引入了额外的变化，但只是在很小的程度上。图形概要 相应的破碎起始被延迟，并且所得碎片的尺寸不太均匀并且分布在更窄的范围内。就早期变形而言，液滴在较高的 M∞ 下经历较不强烈的扁平化和较慢的片材生长。Re 的变化引入了额外的变化，但只是在很小的程度上。图形概要 相应的破碎起始被延迟，并且所得碎片的尺寸不太均匀并且分布在更窄的范围内。就早期变形而言，液滴在较高的 M∞ 下经历较不强烈的扁平化和较慢的片材生长。Re 的变化引入了额外的变化，但只是在很小的程度上。图形概要