• Dr. Tianfeng Lu
  • University of Connecticut
  • Holden Auditorium
  • 4:00 p.m.
  • Faculty Host: Dr. Lin Ma

Recent progress in supercomputing and computational fluid dynamics (CFD) made it feasible to include realistic chemistry and detailed transport of simple fuels in high-fidelity flame simulations, e.g. the petascale direct numerical simulations (DNS) at Sandia National Laboratories, leading to an unprecedented predicting capability for turbulent reacting flows. However, major challenges remain for multidimensional simulations with practical engine fuels. Chemistry of such large hydrocarbons as gasoline, diesel and kerosene may involve hundreds of species and thousands of elementary reactions, and is computationally prohibitive for 2-D and 3-D simulations. Furthermore, the massive simulation data, which can be measured in petabytes, render it difficult to extract salient information from the simulation results. In response to these challenges, different approaches for mechanism reduction, including directed relation graph (DRG), analytically solved linearized quasi steady state approximations, and dynamic chemical stiffness removal, will be presented for systematic generation of compact, accurate and non-stiff chemistry of practical engine fuels that is amenable for large scale combustion simulations. Furthermore, the methods of chemical explosive mode analysis (CEMA) and bifurcation analysis will be presented for systematic identification of critical flame features, such as ignition, extinction, flame instabilities and flame fronts in complex flame configurations at laminar and turbulent, premixed and non-premixed conditions. CEMA will be demonstrated with recent DNS data for lifted jet flames, homogeneous charge compression ignition (HCCI) combustion, and temporal jet flames.

Biography:

Dr. Lu received his B.S. and M.S. in Engineering Mechanics from Tsinghua University in 1994 and 1997, respectively, and Ph.D. in Mechanical and Aerospace Engineering from Princeton University in 2004. Since then he has been a postdoctoral fellow and a research staff at Princeton. He joined the Department of Mechanical Engineering in the University of Connecticut as an Assistant Professor in 2008. Lu’s primary research interest is in combustion and computational fluid dynamics with special interests in chemical kinetics and computational flame diagnostics. He is a member of the Combustion Institute, an Associate Fellow of the AIAA, and the recipient of the inaugural Irvin Glassman young investigator award from the Eastern States Section of the Combustion Institute.