FLAIR Tutorial 4: Fire in a room

This tutorial models a simple three-dimensional room, consisting of four open windows, an open door, a partial wall in the middle and a fire in the far side away from the door. This case shows how to set a fire object. Smoke movement and visibility are also simulated.

Setting up the model

Start FLAIR with the default room

The FLAIR VR-Environment screen should appear, which shows the default room with the dimensions 10mx10mx3m.

Resizing the room

The resized room

You can rotate, translate, or zoom in and out from the room using the left or right mouse buttons, or both together.

To activate the physical models

a. The Main Menu panel

FLAIR always solves pressure and velocities. The temperature is also solved as the default setting.

The 'Models' page of the Flair Main Menu.

b.  to activate smoke movement

image92.gif (33099 bytes)

The CIBSE Guide E (2003) provides the following data:

Material Hfu (MJ/kg) Yco (kg/kg) Ys (kg/kg)
Timber 13.0 0.020 <0.01 - 0.025
PVC- Polyvinyl chloride 5.7 0.063 0.12 - 0.17
PU- Polyurethane (flexible) 19.0 0.042 <0.01 - 0.23
PU- Polyurethane (rigid) 17.9 0.18 0.09 - 0.11
PS- Polystyrene 27.0 0.060 0.15 - 0.17
PP- Polypropylene 38.6 0.050 0.016 - 0.1

If the fire is to represent burning timber, set the 'Heat of Combustion' to 1.3E7 and the 'particulate smoke yield' to 0.02. Click 'Update Rox' to bring the stoichiometric ratio in line with the new heat of combustion.

c. to set ambient conditions

Adding objects to the room

d. add a door

X: 0.0 m

Y: 1.0 m

Z: 2.0 m

X: 0.0 m

Y: 0.0 m

Z: 0.0 m

Set Attributes to the DOOR

e. add the first window

X: 0.0 m

Y: 1.5 m

Z: 0.8 m

X: tick 'at end'

Y: 1.0 m

Z: 1.0 m

f. add the second window

X: tick 'at end'

Y: 4.0 m

Z: 1.0 m

g. add the third window

X: 1.5 m

Y: 0.0 m

Z: 0.8 m

X: Un-tick 'at end' and set 1.0 m

Y: tick 'at end'

Z: 1.0 m

h. add the fourth window

X: 4.0 m

Y: tick 'at end'

Z: 1.0 m

i. add the partition

X: 0.0 m

Y: 3.0 m

Z: 1.8 m

X: 7.0 m

Y: 3.0 m

Z: 0.0 m

j. add the floor

X: 0.0 m

Y: 0.0 m

Z: 0.0 m

k. add the ceiling

X: 0.0 m

Y: 0.0 m

Z: tick 'at end'

l. add the fire

X: 0.5 m

Y: 0.5 m

Z: 0.5 m

X: 10.5 m

Y: 3.5 m

Z: 0.0 m

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Set attributes for Fire

m. To set the grid numbers

n. To set the solver parameters

Running the Solver

To run the PHOENICS solver, Earth, click on 'Run', then 'Solver', then click 'OK' to confirm running Earth. These actions should result in the PHOENICS Earth monitoring screen.

As the Earth solver starts and the flow calculations commence, two graphs should appear on the screen. The left-hand graph shows the variation of solved variables at the monitoring point that was set during the model definition. The right-hand graph shows the variation of errors as the solution progresses.

To the end of the calculation, the monitoring display would be as shown below.

EARTH monitoring screen

Viewing the results

Saving the case

Once a case has been completed, it can be saved to disk as a new Q1 file by 'File - Save working files'. The Q1 and associated output files can be saved more permanently by 'File - Save as a case'.