Droplet Breakup Process in Liquid Fueled Detonation

This talk will examine detonation induced droplet breakup phenomena through numerical simulations and experimental observation of liquid-fueled detonations. Current theoretical understanding and modeling approaches, based on droplet breakup induced by planar shock wave, lack the consideration of the extreme conditions behind the detonation front, characterized by high pressure, temperature and unsteady velocity regimes. A new droplet deformation and breakup model based on the evolution of surface instabilities in instantaneously changing background conditions will be presented. Euler-Lagrange simulations of liquid-fueled (n-Dodecane/Oxygen) small droplet (< 50 micron) detonations is carried out, in the hydrodynamic code FLASH, and compared with experimental observations. Experiments are run for various n-Dodecane fuel droplet size distributions where Mie-scattering and CH* imaging techniques are used to determine the droplet breakup and evaporation distance and reaction front location. Equivalence ratio measurements were used to estimate the velocity deficit from the Chapman-Jouguet (CJ) value for and equivalent gaseous detonation. In addition to the global features of the detonation, such as wave speeds, the droplet lag distance and child droplet cloud size will be compared between experiments and simulation for various parameters.