Mechanical and Civil Engineering Seminar

Mechanical and Civil Engineering Seminar Series

Title: Dynamics of Acoustically Coupled Combustion Instabilities

Abstract: 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 UCLA 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 and, more recently, gas-phase fuel jet combustion with alternative injector configurations. The dynamics of 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) analysis and associated phase portraits enable extraction of characteristic signatures associated with different flame phenomena. Understanding such signatures enables development of reduced order models that can impact eventual combustion control strategies.

Bio: Ann Karagozian is a Distinguished Professor and the Collins Aerospace Term Chair for Innovation in the Department of Mechanical and Aerospace Engineering at UCLA. Her research interests lie in fluid mechanics and combustion as applied to advanced rocket and air breathing propulsion systems. She is the Director of the UCLA Energy and Propulsion Research Laboratory, the UCLA-Air Force Research Laboratory Collaborative Center for Aerospace Sciences, and is the Inaugural Director of the privately endowed UCLA Promise Armenian Institute. Professor Karagozian is a member of the Defense Science Board and was a member of the Air Force Scientific Advisory Board for over 15 years. She is also a Member of the National Academy of Engineering, and is a Fellow of the AIAA, the American Physical Society, and the 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, working with the late Prof. Frank Marble.

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