The Beauty and the Beast:Modeling the Multi-faceted Nature of Chemically Reacting Flows
Speaker: Matthias Ihme, University of Michigan
Series: Other Events
Location: J223 Equad
Date/Time: Thursday, March 1, 2012, 4:00 p.m. - 5:00 p.m.
Combustion in gas turbines and propulsion systems is often accompanied by unstable conditions. Examples of this are thermo-acoustic instabilities in lean premixed gas-turbines, autoignition in oxygen-diluted furnaces, and flame lift-off in high-speed propulsion systems. While such conditions provide unique
opportunities for improving fuel efficiency and reducing pollutant emissions, the accurate characterization and control of such combustion-dynamic processes introduces significant challenges.
This talk discusses current and ongoing research efforts on the fundamental analysis and high-fidelity modeling of unstable chemically reacting flows. Beginning with the stability analysis of laminar flames (the beauty), effects of wall-heat losses, chemical kinetics, and molecular transport properties on the flame-dynamics in a buoyancy-driven jet diffusion flame are investigated. The second part of this presentation addresses the modeling of turbulent flames (the beast), and large-eddy simulations (LES) of a hydrogen jet in a crossflow at gas-turbine relevant operating condition are conducted. Using data from a direct numerical simulation (DNS) database, fundamental modeling assumptions of LES combustion models are investigated. It is shown that flamelet-based combustion models accurately predict the post-reaction zone, and model extensions are discussed to account for flame-stabilization by heat-recirculation in low-strain regions.
The presentation concludes by discussing the potential of utilizing active control for flame-stabilization, and by providing an overview of other research efforts on the modeling of rocket-combustion and detonation waves.
Matthias Ihme is Assistant Professor in the Department of Aerospace Engineering at the University of Michigan. He holds a BSc. degree (2000) from the Munich University of Applied Sciences and a MSc. degree (2002) from the Friedrich-Alexander University Nuremberg/Erlangen, Germany. In 2007, he received his Ph.D. in Mechanical Engineering from Stanford. He is a recipient of the NSF CAREER Award (2009), the ONR Young Investigator Award (2010), and the AFOSR Young Investigator Award (2010).