High-Speed Compressible Turbulent Combustion from Jet Engines to Exploding Stars
Turbulent compressible flames power our everyday life on earth through the heart of many energy generation and propulsion systems, such as gas turbines, internal combustion, and jet engines. They also power the universe through energy produced in stars, such as in the sun, and in the most powerful explosions known in the universe, supernovae explosions. High-speed compressible turbulent combustion imposes numerous fundamental challenges driven by significant compressibility effects and strong coupling between exothermic reactions and the turbulent flow. In recent years, the advent of high-speed, high-resolution flame-flow advanced laser diagnostics has allowed the detailed exploration of the reacting flow dynamics in extreme, previously inaccessible regimes characterized by high flow speeds. Such combustion regimes are fundamental to the operation of many modern propulsion applications, from gas-turbine/internal-combustion engines to scramjets and rotating detonation engines (RDEs). The presentation will overview of a range of phenomena recently discovered in experimental studies of high-speed, compressible, turbulent reacting flows. The topics include intrinsic instabilities of reacting turbulence, flame-scale turbulence production, the onset of catastrophic transitions, spontaneous runaway mechanism of fast turbulent flames, as well as the non-linear compressible combustion regime. Challenges presented by these findings will be discussed based on our fundamental understanding of high-speed compressible turbulent combustion.
Kareem Ahmed, University of Central Florida
Room number or other detail:
Friday, March 27, 2020 - 12:30pm
Dr. Kareem Ahmed is an Assistant Professor at the Department of Mechanical & Aerospace Engineering at the University of Central Florida, a faculty member of the Center for Advanced Turbomachinery & Energy Research and the Florida Center for Advanced Aero-Propulsion, and AIAA Associate Fellow. Before joining UCF he was an Assistant Professor at the Department of Mechanical & Aerospace Engineering at Old Dominion University. Prior to that, he served over three years as a Senior Aero/Thermo Engineer at Pratt & Whitney Military Engines working on Advance Engine Programs and Technologies (F35 and F22 programs). He also served as a faculty at Florida State University. At UCF, Dr. Ahmed leads creative and technologically crucial projects in the area of advanced propulsion and energy research focusing on high-speed compressible turbulent flows, turbulent combustion, deflagrations and detonations, hypersonic and supersonic compressible reacting flows, and advanced laser diagnostics. The research has a broad impact in terms of applications for power generation and gas turbine engines, propulsion jet engines, hypersonics, fire safety, and extends to supernova science (exploding stars, featured in our Science paper). He is a PI of more than $6.47 million in research funding from various organizations (AFOSR, AFRL, DOE, NASA, ACS, Aerojet Rocketdyne, Continental, GE, Siemens). He is leading prime research in detonations for hypersonics and power generation research for AFOSR and DOE, both of which are the first to be explored in the U.S. and has been featured by numerous news media (ABC Channel 9, News 6, UCF news, Pegasus Magazine). He has authored over 125 scholarly articles leading a large research group (27 students and post-docs) and has chaired the graduation 25 students. He also received multiple special awards, including the American Chemical Society - Doctoral New Investigator Award, Combustion Symposium Distinguished Paper Award, and Air Force Office of Scientific Research Faculty Fellowship.