Mach Number Effects on Shock-Induced Deformation and Breakup of Small Acetone Droplets

Understanding the fundamental physics of shock-driven droplet deformation and breakup is crucial for applications in hypersonic droplet impacts, liquid fuel-powered propulsion and combustion systems. This complex process is characterized by the development of interfacial instabilities on the droplet surface, ultimately leading to breakup. Using 2D axisymmetric numerical simulations, we investigate how variations in initial shock strength influence droplet deformation, drag, and breakup for small droplets at high Weber numbers. The simulations were performed over a wide range of Mach numbers using IMPACT^1,2, which employs high-fidelity numerical methods and a level-set-based sharp interface method to capture complex interfacial instabilities and subsequent droplet breakup dynamics. Simulation cases feature a 56.24 μm liquid acetone droplet suspended in air. For some cases, the surface tension was adjusted to achieve high Weber numbers in the post-shock flow. The results reveal how the incident shock Mach number and associated compressibility effects influence droplet dynamics, the onset of Kelvin-Helmholtz instabilities, and breakup morphology.

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²P. Tarey et al., Int. J. Multiph. Flow, 174, 104744, (2024)