Theoretical study of flame propagation through stratified media

Conference · Tue Feb 01 04:00:00 EST 1977

OSTI ID:7304129

Westbrook, C K; Chang, J S

The potential benefits of a stratified charge distribution in internal combustion engines have been known for some time. The capacity to increase overall fuel economy and simultaneously reduce pollutant emissions make the concept extremely attractive. Unfortunately, engines designed to operate under stratified charge conditions have not been able to realize these advantages fully. Detailed study of the physical processes involved is needed to understand why the stratified charge concept has not performed as well as expected and to indicate areas in which improvements may be made. An important part of the overall physical system is the manner in which the reaction zone and the fluid motion in the combustion chamber interact. Results of calculations performed with a numerical model developed expressly for combustion problems are described. The model for the fluid mechanics uses a fully implicit one-dimensional Eulerian difference scheme in which the equations of continuity, momentum and energy conservation, and chemical species transport are all fully coupled and solved simultaneously. The chemical kinetics submodel uses either a global reaction rate mechanism or a detailed multi-reaction, multi-species mechanism. The fuel used in these calculations was methane, chosen primarily because the detailed reaction mechanism for methane combustion is much better understood than that of more complicated hydrocarbon fuels. The qualitative features of the interaction between the fluid dynamics and the detailed chemical kinetics are illustrated effectively with the mechanism chosen, which includes 20 chemical species and 55 reactions. The extent to which the flame speed, heat release, and other quantities of interest could be described by a global reaction mechanism was also investigated.

• Research Organization: California Univ., Livermore (USA). Lawrence Livermore Lab.
• DOE Contract Number: W-7405-ENG-48
• OSTI ID: 7304129
• Report Number(s): UCRL-78925; CONF-770351-1
• Country of Publication: United States
• Language: English

Related Subjects

33 ADVANCED PROPULSION SYSTEMS
330101* -- Internal Combustion Engines-- Spark-Ignition
ALKANES
CHEMICAL REACTION KINETICS
CRYOGENIC FLUIDS
ENGINES
FLUID MECHANICS
FLUIDS
GAS COMBUSTION PROCESS
HYDROCARBONS
INTERNAL COMBUSTION ENGINES
KINETICS
MATHEMATICAL MODELS
MATHEMATICS
MECHANICS
METHANE
NUMERICAL ANALYSIS
ONE-DIMENSIONAL CALCULATIONS
ORGANIC COMPOUNDS
REACTION KINETICS
STRATIFIED CHARGE ENGINES