3 years ago

Droplet and multiphase effects in a shock-driven hydrodynamic instability with reshock

John B. Middlebrooks, Wolfgang J. Black, Roy C. Allen, Constantine G. Avgoustopoulos, Jacob A. McFarland

Abstract

Shock-driven multiphase instabilities (SDMI) are unique physical phenomena that have far-reaching applications in engineering and science such as high energy explosions, scramjet combustors, and supernovae events. The SDMI arises when a multiphase field is impulsively accelerated by a shock wave and evolves as a result of gradients in particle-gas momentum transfer. A new shock tube facility has been constructed to study the SDMI. Experiments were conducted to investigate liquid particle and multiphase effects in the SDMI. A multiphase cylindrical interface was created with water droplet laden air in our horizontal shock tube facility. The interface was accelerated by a Mach 1.66 shock wave, and its reflection from the end wall. The interface development was captured using laser illumination and a high-resolution CCD camera. Laser interferometry was used to determine the droplet size distribution. A particle filtration technique was used to determine mass loading within an interface and verify particle size distribution. The effects of particle number density, particle size, and a secondary acceleration (reshock) of the interface were noted. Particle number density effects were found comparable to Atwood number effects in the Richtmyer–Meshkov instability for small ( \(\sim 1.7~{\upmu }\) m) droplets. Evaporation was observed to alter droplet sizes and number density, markedly after reshock. For large diameter droplets ( \(\sim 10.7~{\upmu }\) m), diminished development was observed with larger droplets lagging far behind the interface. These lagging droplets were also observed to breakup after reshock into structured clusters of smaller droplets. Mixing width values were reported to quantify mixing effects seen in images.

Publisher URL: https://link.springer.com/article/10.1007/s00348-018-2547-7

DOI: 10.1007/s00348-018-2547-7

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