Vortex-Induced Interfacial Instability As A Means to Improve Droplet Entrainment

Modern laboratory experiments for hybrid rocket motors are concerned with increasing the fuel regression rate to improve the overall impulse of the engine. The simulations developed in this study demonstrate a novel method to promote droplet formation, atomization, and entrainment of liquid fuel into the gaseous oxidizer flow. A pair of two-dimensional isothermal cases, both with and without the ignition source for the combustion reaction, are conducted to compare its hydrodynamic influence on the oxidizer-fuel interactions. By exploiting the geometry of the ignition source upstream of the fuel, it has been found that the shedding vortices are capable of inducing instabilities at the fuel/oxidizer interface without increasing oxidizer flow rate. These investigations are performed using Volume of Fluid method and were inspired by a slab motor experiment conducted at CHREST at the University at Buffalo. The results indicate that these vortex-induced instabilities are generated faster and cause improved fuel entrainment in the case where the ignition source is present. This vortex-induced method of improved fuel mixing can provide new avenues for the development of future hybrid rocket motors.