Effect of nonunity Lewis number and finite-rate chemistry on the dynamics of a hydrogen-air jet diffusion flame

In jet diffusion flames, buoyancy-influenced torroidal vortices roll outside the flame surface when the annulus air flow is low. The temporal and spatial evolution of these vortices changes the stretch along the flame surface, which results in a wrinkled laminar flame. A time-dependent, axisymmetric...

Full description

Saved in:
Bibliographic Details
Published in:Combustion and flame 1994, Vol.96 (1), p.60-74
Main Authors: Katta, V.R., Goss, L.P., Roquemore, W.M.
Format: Article
Language:English
Subjects:
08 HYDROGEN
083000 - Hydrogen- Combustion- (1990-)
ACTIVATION ENERGY
Applied sciences
CHEMICAL REACTION KINETICS
COMBUSTION KINETICS
Combustion of gaseous fuels
Combustion. Flame
ENERGY
Energy. Thermal use of fuels
ENTHALPY
Exact sciences and technology
FLAMES
FLOW MODELS
FLOW RATE
FORMATION HEAT
FUELS
HYDROGEN FUELS
KINETICS
MATHEMATICAL MODELS
MORPHOLOGY
PHYSICAL PROPERTIES
REACTION HEAT
REACTION KINETICS
SYNTHETIC FUELS
Theoretical studies. Data and constants. Metering
THERMODYNAMIC PROPERTIES
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:In jet diffusion flames, buoyancy-influenced torroidal vortices roll outside the flame surface when the annulus air flow is low. The temporal and spatial evolution of these vortices changes the stretch along the flame surface, which results in a wrinkled laminar flame. A time-dependent, axisymmetric mathematical model having a detailed chemical-kinetics mechanism is used to simulate the wrinkled flame surface of a low-speed H 2-air diffusion flame. The effects of Lewis number and finite-rate chemistry on the steady-state and dynamic flame structures are examined. Results obtained with different models indicate that the size and shape of the outer structures are unaffected by the unity-Lewis-number and fast-chemistry assumptions. Experiments showed that the flame temperature tends to increase when the flame is bulging and decrease when it is squeezing. The lower Lewis number inside the flame—not the change in the Damkohler number—was found to be responsible for the observed fluctuations in the flame temperature. Preferential mass diffusion of different species causes an increase in water in the bulging regions of the flame and an increase in radicals in the squeezing regions.
ISSN:0010-2180
1556-2921
DOI:10.1016/0010-2180(94)90158-9