Encyclopaedia Index

### TITLE : COMBUSTION AND NOx MODELLING FOR 2-D TURBULENT FLAME

BY : Radian Corporation - P Adnani
CHAM Development Team - M R Malin

FOR : Radian Corporation, Irvine, USA

DATE : 1994 PHOENICS Version : 2.1

### MODEL OBJECTIVES :

- The main objective of the model is to predict the NOx formation when
combustion products from gas-fired burners, operating at different
stoichiometries, are mixed in a large utility boiler.

- The model may be used to help determine the optimum firing condition
for each burner in a utility boiler.

### FLOW DETAILS :

The model is intended for inclusion in a 3D test-boiler BFC
geometry, but was developed on a 2D pipe geometry with somewhat
arbitrary operating conditions, as indicated below:

- 2D steady turbulent diffusion flame in a pipe of 0.32m diameter
and 2m length.
- Cylindrical-polar mesh with 40 radial and 20 axial cells.
- Coaxial fuel and oxidiser streams are admitted separately into the
pipe and then they burn in a turbulent diffusion flame.
- The fuel jet enters through a pipe of 0.16m diameter and comprises
2 fuels (CO and H2), N2, CO2 and H2O at a temperature of 1754 C.
- The oxidiser jet enters through an annulus and comprises O2, N2, CO2
and H2O at a temperature of 1518 C.
- The oxygen supply is 66% above stoichiometric.

### MAIN FEATURES OF MODEL:

Turbulence is represented via the k-e turbulence model.
The main combustion process is modelled by the oxidation of CO and
H2 by two infinitely fast, global irreversible reactions.
The reactants participating in these reactions cannot exist at the
same place at any time; and the composition is determined via the
solution of the mixture fraction.
The enthalpy-temperature relationship allows for variable specific
heats and heats of reaction.
Radiative heat transfer is modelled via the solution of the
radiosity equation for a gray medium.
NO emissions calculated from the Zeldovich mechanism coupled with
a fuel kinetics mechanism consisting of 8 reactions.
PICTURES :

VELOCITY VECTORS

O2 MASS-FRACTION CONTOURS

TEMPERATURE CONTOURS ( DEG K )

NO MASS-FRACTION CONTOURS

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