Autoignited laminar lifted flames of propane in coflow jets with tribrachial edge and mild combustion

Characteristics of laminar lifted flames have been investigated experimentally by varying the initial temperature of coflow air over 800 K in the non-premixed jets of propane diluted with nitrogen. The result showed that the lifted flame with the initial temperature below 860 K maintained the typica...

Full description

Saved in:
Bibliographic Details
Published in:Combustion and flame 2009-02, Vol.156 (2), p.396-404
Main Authors: Choi, B.C., Kim, K.N., Chung, S.H.
Format: Article
Language:English
Subjects:
AIR
Applied sciences
AUTOIGNITION
COMBUSTION
Combustion. Flame
Correlation
CORRELATIONS
Delay
Energy
Energy. Thermal use of fuels
Exact sciences and technology
FLAME PROPAGATION
HEAT LOSSES
HEIGHT
Ignition
Ignition delay
INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY
JETS
Laminar
LAMINAR FLAMES
Liftoff
Liftoff height
Mild combustion
NITROGEN
NONLINEAR PROBLEMS
PROPANE
TEMPERATURE DEPENDENCE
TEMPERATURE RANGE 0400-1000 K
Theoretical studies. Data and constants. Metering
TIME DELAY
Tribrachial flame
Tribrachial flames
VELOCITY
Citations: Items that cite this one
Online Access:Get full text
Tags: Add Tag
No Tags, Be the first to tag this record!
Description
Summary:Characteristics of laminar lifted flames have been investigated experimentally by varying the initial temperature of coflow air over 800 K in the non-premixed jets of propane diluted with nitrogen. The result showed that the lifted flame with the initial temperature below 860 K maintained the typical tribrachial structure at the leading edge, which was stabilized by the balance mechanism between the propagation speed of tribrachial flame and the local flow velocity. For the temperature above 860 K, the flame was autoignited without having any external ignition source. The autoignited lifted flames were categorized in two regimes. In the case with tribrachial edge structure, the liftoff height increased nonlinearly with jet velocity. Especially, for the critical condition near blowout, the lifted flame showed a repetitive behavior of extinction and reignition. In such a case, the autoignition was controlled by the non-adiabatic ignition delay time considering heat loss such that the autoignition height was correlated with the square of the adiabatic ignition delay time. In the case with mild combustion regime at excessively diluted conditions, the liftoff height increased linearly with jet velocity and was correlated well with the square of the adiabatic ignition delay time.
ISSN:0010-2180
1556-2921
DOI:10.1016/j.combustflame.2008.10.020