1、Advances in Turbulent Combustion Modeling for Gas-phase and Multiphase Combustion

Combustion systems for transportation and aviation are operated with gaseous and liquid fuels. The combustion of these fuels requires the consideration of competing physical processes, involving liquid-fuel injection, turbulent mixing, ignition, flame-stabilization, and emissions. This seminar discusses recent progress and challenges on the modeling, simulation and analysis of turbulent combustion processes, pertaining to the prediction of unstable combustion processes and the high-fidelity modeling of spray combustion.

We begin by reviewing physical mechanisms of turbulent combustion processes, combustion regimes, and the development of theory to guide physical understanding and subsequent computational modeling. We will then proceed by discussing recent progress on the development of fidelity-adaptive combustion models, the assessment of model compliance, and the physical modeling of spray-combustion, multicomponent evaporation, and fuel-effects on flame-stabilization. These theoretical findings and computational models will then be synthesized and applied to practically relevant combustion problems, including lifted and vitiated turbulent flames, DNS of a turbulent counterflow spray flame to study effects of spray-flame bifurcation, and a realistic gas-turbine combustor to assess fuel effects on combustion stability.

The seminar closes by identifying open research questions and future research needs.

2、Novel Combustion Concepts

Current combustion technologies for aviation gas-turbines, stationary power generation, and internal combustion engines are relatively mature, and only incremental improvements in performance and combustion efficiency can be expected. However, new combustion concepts are needed to comply with new regulations on exhaust emissions, combustor stability, and to enable the utilization of emerging and alternative fuels. One such promising combustion concept is matrix-stabilized combustion in porous media. In these burners combustion is facilitated within the voids of a porous heat-conducting matrix, thereby achieving superadiabatic combustion, significant reductions in pollutant emissions, and extended power modulation.

In this seminar, we will examine scientific aspects of porous media combustion that compreise the numerical modeling, the development of advanced diagnostics techniques, and experimental testing. Of particular interest is the experimental characterization of the internal flame structure inside the porous matrix. For this, advanced X-ray computed tomography diagnostics is developed to obtain three-dimensional temperature fields within the porous burner. The utility of these temperature measurements in assessing the accuracy of low-order volume-averaged models is discussed, and the need for durability tests in conjunction with high-resolution micro-XCT diagnostics for characterizing the long-time performance and thermo-structural stability of porous matrix burners is emphasized.

 

Brief Biography：Matthias Ihme is Associate Professor in the Department of Mechanical Engineering at Stanford University. He holds a BSc. degree in Mechanical Engineering and a MSc. degree in Computational Engineering. In 2008, he received his Ph.D. in Mechanical Engineering from Stanford. After being on the faculty of the Aerospace Engineering Department at the University of Michigan for five years, he returned to Stanford in 2013. He is a recipient of the NSF CAREER Award (2009), the ONR Young Investigator Award (2010), the AFOSR Young Investigator Award (2010), the NASA Early Career Faculty Award (2015), and the Hiroshi Tsuji Early Career Research Award (2017).  His research interests are broadly on the computational modeling of reacting flows, the development of numerical methods, and the investigation of advanced combustion concepts.