Events Calendar

Aerospace and Mechanical Engineering Seminar Series

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