Towards Large Eddy Simulations of Flame Extinction and Carbon Monoxide Emission in Compartment Fires.
Towards Large Eddy Simulations of Flame Extinction and
Carbon Monoxide Emission in Compartment Fires.
(648 K)
Hu, Z.; Utiskul, Y.; Quintiere, J. G.; Trouve, A.
Volume 31; Part 2;
Combustion Institute, Symposium (International) on
Combustion, 31st. Proceedings. Volume 31. Part 2.
August 5-11, 2006, Heidelberg, Germany, Combustion
Institute, Pittsburgh, PA, Barlow, R. S.; Sick, V.;
Glarborg, P.; Yetter, R. A., Editor(s)(s), 2537-2545 pp,
2007.
Keywords:
combustion; fire research; compartmernt fires; flame
extinguishment; carbon monoxide; emissions; ventilation;
combustion models; computational fluid dynamics;
diffusion flames; vitiation; hydrocarbons; flammability;
equations
Abstract:
The general objective of this research is to adapt
current combustion modeling capabilities used in
computational fluid dynamics solvers to the treatment of
under-ventilated compartment fires. More specifically,
we consider in the present study two models proposed to
describe: diffusion flame extinction due to air
vitiation; and the emission of carbon monoxide (CO) and
unburnt hydrocarbon (HC) mass in a compartment fire. The
flame extinction model is based on a flammability
diagram parametrized in terms of vitiated air
properties. The CO/HC mass model is based on: a
transport equation for fuel mass; a comparison of this
fuel mass to a Burke-Schumann chemical-equilibrium
expression; and an interpretation of the difference as
a measure of incomplete combustion. Both models are
implemented into a large eddy simulation solver
developed by the National Institute of Standards and
Technology, USA. The models performance is tested via
detailed comparisons with an experimental database
corresponding to reduced-scale compartment fires. The
study considers two cases that correspond to different
values of the fire room global equivalence ratio and are
representative of strikingly different flame behaviors.
The comparative tests serve to evaluate the
general ability of the models to describe the transition
from extinction-free conditions to conditions in which
the flame experiences partial or total quenching, as
well as the transition from fire regimes with no or
little CO emission to regimes that emit hazardous
levels.
Building and Fire Research Laboratory
National Institute of Standards and Technology
Gaithersburg, MD 20899