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You are invited to hear
Department of Aerospace Engineering
Texas A&M University
September 14 @ 11 am
Montgomery Knight Room 317
Abstract:
Turbulent reacting flows are pervasive both in our daily lives on Earth and in the Universe. They power modern society being at the heart of many energy generation and propulsion systems, such as gas turbines, internal combustion and jet engines. At the same time, they also power the Universe through the energy produced in stellar interiors – both quiescently, as in the Sun, and also violently, as in the most powerful explosions in the Universe known as Type Ia supernovae. Despite this ubiquity in Nature, turbulent reacting flows still pose a number of fundamental questions concerning their structure and dynamics often exhibiting surprising and unexpected behavior. In recent years, the advent of large-scale direct numerical simulations (DNS) has allowed the detailed exploration of the reacting flow dynamics in extreme, previously inaccessible regimes characterized by high flow speeds, significant compressibility effects, and strong coupling between exothermic reactions and the turbulent flow. Such combustion regimes are fundamental to the operation of many modern propulsion applications from scramjets to detonation-based engines. Furthermore, in certain cases these regimes can now be studied with remarkable realism using full-scale combustors, realistic fuels, and engine-relevant conditions. This talk will present an overview of a range of phenomena recently discovered in DNS of high-speed, premixed, turbulent reacting flows. These include intrinsic instabilities of reacting turbulence, onset of catastrophic transitions, e.g., spontaneous detonation formation, qualitative changes in the nature of the turbulent cascade in the presence of exothermic reactions, as well as the onset of distributed burning regimes at high turbulent intensities. I will discuss challenges presented by these findings both in the context of our theoretical understanding of reacting flows, and also in the context of modern modeling paradigms, such as Large Eddy Simulations.
Bio:
Alexei Poludnenko received his Bachelor degree in Physics and Mathematics from the National University “Kyiv-Mohyla Academy” in Kyiv, Ukraine, and Masters and Ph.D. degrees in Physics and Astronomy from the University of Rochester. Upon graduation, he joined the Department of Energy ASC Flash Center at the University of Chicago as a postdoctoral researcher. Subsequently, Dr. Poludnenko worked at the Naval Research Laboratory first as a National Research Council postdoctoral fellow and later as a permanent research staff member. Currently, he is an associate professor in the Department of Aerospace Engineering at the Texas A&M University. His research includes theoretical and computational studies of turbulent combustion in chemical and thermonuclear systems, numerical algorithm development for computational fluid dynamics, and high-performance computing. Dr. Poludnenko was a recipient of the Distinguished Paper Award at the 36th International Symposium on Combustion, the 2016 François Frenkiel Award for Fluid Mechanics of the American Physical Society Division of Fluid Dynamics, and the Alan Berman Research Publication Award of the US Naval Research Laboratory.
