Mechanical and Civil Engineering Seminar

Mechanical and Civil Engineering Seminar Series

Title: Liquid Breakup at Supercritical Conditions: Toward Understanding Mixing and Combustion at Extreme Conditions

Abstract: The design of liquid-fueled propulsion systems has shifted toward high pressures and temperatures exceeding the critical point of the fuel-air mixture, known as supercritical conditions to enable performance gain, lighter and more reliable systems for aviation, power generation, ground and space transportation. Shock interaction with fuel sprays or a dense droplet medium is a multiscale phenomenon governing shock-enhanced mixing in liquid-fueled scramjets and rotating/pulsed detonation engines that can revolutionize the design of future commercial hypersonic flights. However, our understanding of the interaction of shock-laden flows with liquid droplets is significantly less developed than its gas-phase counterpart. Meanwhile, the complex behavior of multiphase flows at supercritical conditions is less understood due to the dearth of detailed experimental data at such extreme conditions. I will introduce a new computational framework comprised of Molecular Dynamics and Direct Numerical Simulations and elucidate the mechanisms underlying shock-driven droplet breakup at supercritical conditions from molecular-level interactions to higher scales. The results indicate that supercritical droplet-shock interaction poses unique shock dynamics departing from its subcritical counterpart causing droplet transition from classical two-phase breakup to gas-like diffusion mixing. The generated knowledge establishes the secondary droplet breakup morphologies at supercritical conditions for the first time which will pave the way toward a better understanding of supercritical fuel/air mixing and achieving more stable combustion processes in the next generation of high-speed propulsion systems.

Bio: Dorrin Jarrahbashi is an Assistant Professor at the J. Mike Walker '66 Department of Mechanical Engineering at Texas A&M University. She completed her post-doctoral studies at Georgia Institute of Technology and received her PhD in Mechanical & Aerospace Engineering from University of California, Irvine. Her research focuses on developing computational models from molecular level to higher scales to understand multiphase flow mixing and combustion at extreme conditions. She also contributes to the bottom-up fabrication of functional nanostructures by developing novel nanoparticle spray deposition techniques using supercritical flows. She is the recipient of NSF CAREER Award, American Physical Society-Division of Fluid Dynamics Gallery of Fluid Motion award, and Society of Women Engineers Fellowship. She leads a number of projects supported by NSF, Office of Naval Research, and industry and has published her work in Nature, Combustion & Flame, and Journal of Fluid Mechanics, featuring on the journal cover.

NOTE: At this time, in-person Mechanical and Civil Engineering Lectures are open to all Caltech students/staff/faculty/visitors.