BY : Dr S V Zhubrin, CHAM Ltd

DATE : November, 2000

FOR : Demonstration case for V3.3.1

The flames in combustors can be stabilized by recirculations behind the bluff bodies. V-gutter flameholders are often used in gas turbines afterburners.

The case is aimed to demonstrate the 'cut-off' technique of PARSOL method to represent the inclined walls of combustor and flameholders on Cartesian grid.

The demonstration case considers the turbulent two-stream diffusion flame in a 2D model of afterburner. Two flameholders placed in the flow are of the open-mouth-type V-gutters.

The task is to calculate the temperature and composition of combustion gases along with all related field distributions.

The independent variables of the problem are the two components of cartesian coordinate system, namely X and Y.

The main dependent (solved for) variables are:

- Pressure, P1
- Three components of velocity, U1 and V1,
- Turbulence energy and its dissipation rate, KE, EP
- Gas total enthalpy, H1,
- Gas mixture fraction, MIXF and
- Fuel mass fraction, FUEL.

The K-epsilon model, KEMODL, closed by wall functions is used to calculate the distribution of turbulence energy and its dissipation rate from which the turbulence viscosity is deduced.

Combustion is treated as a single-step irreversible chemical reaction with a finite reaction rate between fuel and oxygen. The rate of combustion is modelled according to the "eddy-break-up" concept.

The gas density is computed from the local pressures, gas temperatures and local mixture molecular masses.

The specific enthalpies are related to gas temperatures, fuel mass fraction and the heat of combustion.

The plots show the distribution of the temperature, velocities and pressure within the afterburner.

Pictures are as follows :

- Geometry and the grid
- Velocity vectors
- Temperature distribution
- Fuel mass fractions
- Combustion product mass fractions
- Air mass fractions
- Turbulence viscosity contours
- Turbulence energy contours
- Turbulence length scale contours
- Pressure contours

All model settings have been made in VR-Editor of PHOENICS 3.3.1 The relevant Q1 file can be inspectedby clicking here.

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