Conferences, Lectures, & Seminars
Events for October
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Aerospace and Mechanical Engineering Seminar Series
Wed, Oct 07, 2015 @ 03:30 PM - 04:30 PM
Aerospace and Mechanical Engineering
Conferences, Lectures, & Seminars
Speaker: Forman Williams, Professor Emeritus of Mechanical and Aerospace Engineering at the University of California at San Diego
Talk Title: Quasi-Steady Combustion of Normal Alkane Droplets Supported by Cool-Flame Chemistry
Series: Aerospace and Mechanical Engineering Seminar Series
Abstract: Combustion of liquid fuel droplets in gaseous oxidizing atmospheres has been studied thoroughly for more than 60 years because of interest in applications related to liquid-fuel propulsion. Idealized models of droplet combustion impose spherical symmetry to simplify the equations and contribute to understanding. In both theory and experiment, because of the small ratio of gas to liquid density the gas-phase equations are quasi-steady, with fuel and oxygen forming equilibrium products and releasing heat at a hot spherical flame. Microgravity experiments enable spherically symmetrical droplet combustion to be investigated for larger droplets that experience longer burning times. Nearly 5 years ago, experiments employing normal alkane droplets initially 3 or 4 mm in diameter, burning in air, performed in the International Space Station, revealed a different mode of combustion in which quasi-steady burning was supported not by hot-flame chemistry but rather by cool-flame chemistry, involving only partial burning of the fuel and oxygen and not producing equilibrium products. Cool flames, first named that in 1934 and thought to be responsible for the will o' the wisp, are fleeting blue flames caused by the same chemistry that produces two-stage ignition processes, which are being studied for potential applications in RCCI engines. The seminar will contrast hot-flame and cool-flame chemistry and describe current experimental and theoretical efforts to improve understanding of quasi-steady droplet combustion supported by cool-flame chemistry.
Biography: Dr. Forman A. Williams is a Distinguished Emeritus Professor of Engineering Physics and Combustion (2015-present) in the Department of Mechanical and Aerospace Engineering at University of California, San Diego. He is a member of the National Academy of Engineering and a Foreign Corresponding Member of the National Academy of Engineering of Mexico. He is a Fellow of the American Academy of Arts and Sciences, the American Institute of Aeronautics and Astronautics, the American Physical Society, the American Society of Mechanical Engineers, and the Society for Industrial and Applied Mathematics. Among his numerous honors, Prof. Williams has been awarded the Silver and the Bernard Lewis Gold Medal of The Combustion Institute, as well as the prestigious AIAA Propellants and Combustion Award. He has authored more than 400 publications, including textbook Combustion Theory. His research focus is on flame theory, asymptotic analysis, combustion in turbulent flows, fire research, reactions in boundary layers, and other areas of combustion and fluid mechanics.
Host: Prof. Fokion Egolfopoulos
Location: Seaver Science Library (SSL) - 150
Audiences: Everyone Is Invited
Contact: Valerie Childress
This event is open to all eligible individuals. USC Viterbi operates all of its activities consistent with the University's Notice of Non-Discrimination. Eligibility is not determined based on race, sex, ethnicity, sexual orientation, or any other prohibited factor. -
Aerospace and Mechanical Engineering Seminar Series
Wed, Oct 14, 2015 @ 03:30 PM - 04:30 PM
Aerospace and Mechanical Engineering
Conferences, Lectures, & Seminars
Speaker: Alexei Poludnenko, Naval Research Laboratory
Talk Title: Turbulent Combustion: From a Jet Engine to an Exploding Star
Series: Aerospace and Mechanical Engineering Seminar Series
Abstract: Turbulent reacting flows are pervasive both in our daily lives on Earth and in the Universe. They power the modern society being at the heart of many energy generation and propulsion systems, such as gas turbines, internal combustion and jet engines. On astronomical scales, thermonuclear turbulent flames are the driver of some of the most powerful explosions in the Universe, knows as Type Ia supernovae. These are crucibles, in which most of the elements around us from oxygen to iron are synthesized, and in the last 20 years they have led to one of the most remarkable discoveries in modern science, namely of the existence of dark energy. Despite this ubiquity in Nature, turbulent reacting flows remain poorly understood still posing a number of fundamental questions. In this talk I will give an overview of the numerical and theoretical work at the Naval Research Laboratory over the recent years aimed at studying both chemical and thermonuclear turbulent flames. I will highlight several surprising phenomena that have emerged in the course of this work, in particular, in the context of the intrinsic instabilities of high-speed turbulent reacting flows, as well as some of the outstanding open challenges. Finally, I will briefly discuss the implications of this work for the development of the next generation of accurate, predictive turbulent flame models required for the design of practical combustion applications.
Biography: Alexei Poludnenko received his Ph.D. in Physics and Astronomy from the University of Rochester in 2004. Upon graduation, he joined the Department of Energy ASC Flash Center at the University of Chicago as a postdoctoral researcher, where he worked on theoretical studies of astrophysical supernovae explosions and numerical modeling of thermonuclear deflagrations and detonations. Since joining the Naval Research Laboratory in 2007, first as a National Research Council postdoctoral fellow and later as a permanent research staff member, Dr. Poludnenko has been working on a wide range of topics in combustion, numerical algorithm development for hydro- and magnetohydrodynamics, and high-performance computing. In recent years, he has been leading the research program at NRL focused on theoretical and computational studies of turbulent combustion in chemical and astrophysical systems.
Host: Prof. Fokion Egolfopoulos
Location: Seaver Science Library (SSL) - 150
Audiences: Everyone Is Invited
Contact: Valerie Childress
This event is open to all eligible individuals. USC Viterbi operates all of its activities consistent with the University's Notice of Non-Discrimination. Eligibility is not determined based on race, sex, ethnicity, sexual orientation, or any other prohibited factor. -
Aerospace and Mechanical Engineering Seminar Series
Wed, Oct 21, 2015 @ 03:30 PM - 04:30 PM
Aerospace and Mechanical Engineering
Conferences, Lectures, & Seminars
Speaker: John Junkins, Professor of Aerospace Engineering at Texas A&M University
Talk Title: Astrodynamics for Modern Space Operations: Recent Analytical, Computational and Experimental Research
Series: Aerospace and Mechanical Engineering Seminar Series
Abstract: We address recent advances in analytical, computational and experimental studies aimed at challenges posed by the growth of space debris in near earth orbit. Since two large satellite collisions in 2007 and 2009, space debris has emerged as a challenge to the future utilization of low earth orbit. The Kessler Syndrome describes the potentially unstable increase in the population of space debris due to the increase in future probability of collisions. The future collision probability is increased by the large debris population wake of each collision. Some studies indicate that removing largest space derelict objects such as spent boosters and dead satellites is the most effective means for arresting growth of space debris, along with end-of-life de-orbit plans for all future launches. While present day collision risks are tolerable for most purposes, one or two additional large object collisions could increase the probability of collision to a point that future utilization of some orbit regimes could be severely degraded. This paper overviews two sets of research relevant to these challenges: (1) Methods for de-orbiting large derelict objects not designed for rendezvous and docking, and (2) new methods in astrodynamics for rapid/precise orbit propagation and mission analysis relevant to the challenges posed by orbit debris.
For both sets of research, we overview key issues, basic developments, and current status of closure between theory, computation and experiments. We discuss critical obstacles for these developments to be realized as operational technology for debris mitigation missions. Finally, we observe related applications where the methodology presented is potentially transferrable.
Host: Prof. Firdaus Udwadia
Location: Seaver Science Library (SSL) - 150
Audiences: Everyone Is Invited
Contact: Valerie Childress
This event is open to all eligible individuals. USC Viterbi operates all of its activities consistent with the University's Notice of Non-Discrimination. Eligibility is not determined based on race, sex, ethnicity, sexual orientation, or any other prohibited factor. -
Aerospace and Mechanical Engineering Seminar Series
Wed, Oct 28, 2015 @ 03:30 PM - 04:30 PM
Aerospace and Mechanical Engineering
Conferences, Lectures, & Seminars
Speaker: Felipe de Barros, Assistant Professor of Civil & Environmental Engineering at the University of Southern California
Talk Title: TBA
Series: Aerospace and Mechanical Engineering Seminar Series
Host: Prof. Geoffrey Spedding
Location: Seaver Science Library (SSL) - 150
Audiences: Everyone Is Invited
Contact: Valerie Childress
This event is open to all eligible individuals. USC Viterbi operates all of its activities consistent with the University's Notice of Non-Discrimination. Eligibility is not determined based on race, sex, ethnicity, sexual orientation, or any other prohibited factor.
