Knocking in internal combustion engines is a commonly encountered phenomenon but fundamental understanding of the underlying physical mechanism is lacking. In the present study, direct numerical simulations (DNS) of reactive mixtures with temperature and composition fluctuations are conducted in order to provide insights into the auto-ignition and subsequent development of knock and detonation. High order discretization schemes with shock-capturing algorithms allow an accurate realization of the flame-acoustic interaction and the evolution of detonation accompanied by high pressure peaks. Parametric studies using one- and two-dimensional DNS at engine-like conditions allow a systematic characterization of the onset of knock in terms of key effects such as bulk mixture conditions and heat release rate. The original theory by Bradley and coworkers is revised to properly predict the onset of detonation and further validated by simulation and experimental data.
13/07/2020
The webinar can be reached at this Goggle Meet link:
meet.google.com/cfr-dayy-zpi
at 11:00am (Italian time)
Hong G. Im received his B.S. and M.S. in from Seoul National University, and Ph.D. from Princeton University. After postdoctoral researcher appointments at the Center for Turbulence Research, Stanford University, and at the Combustion Research Facility, Sandia National Laboratories, he held assistant/associate/full professor positions at the University of Michigan. He joined KAUST in 2013 as a Professor of Mechanical Engineering. He is a recipient of the NSF CAREER Award and SAE Ralph R. Teetor Educational Award, and has been inducted as a Fellow of the Combustion Institute and American Society of Mechanical Engineers (ASME) and an Associate Fellow of American Institute of Aeronautics and Astronautics (AIAA). He has also served as an Associate Editor for the Proceedings of the Combustion Institute, and currently on the Editorial Board for Energy and AI. Professor Im’s research and teaching interests are primarily fundamental and practical aspects of combustion and power generation devices using high-fidelity computational modeling. Current research activities include direct numerical simulation of turbulent combustion at extreme conditions, large eddy simulations of turbulent flames at high pressure, modeling of low grade and alternative fuels, spray and combustion modeling in advanced internal combustion engines, advanced models for soot formation, and electrical field effects on flames.