Abstract
The influence of thermal stratification on autoignition at constant volume and high pressure is studied by direct numerical simulation (DNS) with detailed hydrogen/air chemistry. Parametric studies on the effect of the initial amplitude of the temperature fluctuations, the initial length scales of the temperature and velocity fluctuations, and the turbulence intensity are performed. The combustion mode is characterized using the diagnostic measures developed in Part I of this study. Specifically, the ignition front speed and the scalar mixing timescales are used to identify the roles of molecular diffusion and heat conduction in each case. Predictions from a multizone model initialized from the DNS fields are presented and differences are explained using the diagnostic tools developed.
Original language | English |
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Pages (from-to) | 145-159 |
Number of pages | 15 |
Journal | Combustion and Flame |
Volume | 145 |
Issue number | 1-2 |
DOIs | |
State | Published - Apr 2006 |
Externally published | Yes |
Funding
Sandia National Laboratories (SNL) is a multiprogram laboratory operated by Sandia Corporation, a Lockheed Martin Company, for the United States Department of Energy under Contract DE-AC04-94-AL85000. The work at SNL was supported by the Division of Chemical Sciences, Geosciences and Biosciences, the Office of Basic Energy Sciences, the U.S. Department of Energy. Calculations were performed at SNL and at the National Energy Research Scientific Computing Center, which is supported by the Office of Science of the U.S. Department of Energy under Contract DE-AC03-76SF00098. The High Performance Computing and Networking department at SNL provided access to a 256-processor Infiniband testbed. The authors acknowledge fruitful discussions with Drs. John Hewson, Hong Im, John Dec, and Magnus Sjöberg.
Keywords
- Direct numerical simulation
- HCCI
- Ignition
- Multizone model