Professor Ann R. Karagozian
Mechanical & Aerospace Engineering Department
UCLA

Acoustically-coupled combustion instabilities can result in large scale, potentially catastrophic pressure oscillations in aerospace propulsion systems, including liquid rocket engines (LREs) and gas turbine engines. A fundamental understanding of the interactions among flow and flame hydrodynamics, acoustics, and reaction kinetics is essential to determining combustor stability and controlling combustion processes. Over the past several years our group at the UCLA Energy and Propulsion Research Laboratory has been pursuing fundamental experiments that can shed light on combustion instabilities and their control, including exploration of the effects of external acoustic perturbations on liquid nanofuel combustion as well as gas-phase fuel jet combustion for alternative geometrical configurations. Phenomena such as periodic liftoff and reattachment, periodic partial extinction and reignition, and full extinction are explored and quantified via phase-locked OH* chemiluminescence and high speed visible imaging. Proper orthogonal decomposition (POD) modes and coefficient plots of time-resolved imaging enables characterization of various dynamical behaviors and signatures associated with different phenomena. Understanding such characteristic signatures enables development of reduced order models that can impact eventual control strategies.


About the speaker...

Ann Karagozian is a Distinguished Professor in the Department of Mechanical and Aerospace Engineering at UCLA and heads the UCLA Energy and Propulsion Research Laboratory and the UCLA-Air Force Research Laboratory Collaborative Center for Aerospace Sciences. Her research interests lie in fluid mechanics and combustion as applied to improved energy efficiency, reduced emissions, and advanced air breathing and rocket propulsion systems. Professor Karagozian is a current member of the Air Force Scientific Advisory Board, having served previously as SAB Vice Chair (2005-2009) and twice receiving the Air Force Decoration for Exceptional Civilian Service. She is a Member of the National Academy of Engineering and is a Fellow of the American Institute of Aeronautics and Astronautics (AIAA), the American Physical Society (APS), and the American Society of Mechanical Engineers (ASME). She received her B.S. in Engineering from UCLA and her M.S. and Ph.D. in Mechanical Engineering from the California Institute of Technology. She is a member of the Board of Trustees of the Institute for Defense Analyses (IDA) and is an alumna of and mentor for the IDA Defense Science Study Group. Prof. Karagozian is also the Inaugural Director of The Promise Armenian Institute at UCLA.