Manufacturing & Infrastructure Technology

Evaluation of PHOENICS CFD fire model against

room corner fire experiments

Yunlong Liu and Vivek Apte

Presentation content

Introduction

CSIRO Room Corner Fire

Experiments

Numerical Details

Results and Discussion

Conclusion

Introduction

Introduction

Accidental fire loss is big

Experimental method

Numerical method

Design fire concept

Introduction

Implementation of Design Fire - Stage 1

Validate software Packages:Input Structure geometry, experimentally

measured HRR, smoke RR into the CFD ModelOutput Temperature field, smoke concentration

field, turbulence model, BC, radiation model, mesh layout

What is needed:Experimentally measured HRR, smoke RR,Temperature field and smoke concentration

field

Introduction

Implementation of Design Fire - Stage 2

Find the design fire:Input the location of the fire source, turbulence

model, BC, radiation model, mesh layoutOutput HRR, Smoke RR, Temperature field,

smoke concentration field

What is needed:Experimentally measured Temperature field andsmoke concentration field needed for validation

Introduction

Implementation of Design Fire - Stage 3

Apply the Design Fire to Fire Engineering Consulting:Input structure size, Fire location, mesh layout,

turbulence model, radiation model, BCOutput HRR, Smoke RR, temperature field, smoke

concentration field, visibility, evacuation time What is needed:

Structure size and fire location from the clients, mesh layout, turbulence model, radiation model andBC from stage 1, HRR and smoke RR from stage 2

Introduction

Software platform:

Zone model CFAST, BranzFire

Field model (CFD model) CFX, FLUENT, PHOENICS, FDS, SmartFire

CSIRO Room Corner Fire Experiments

CSIRO Room Corner Fire Experiments

Wall lining material: Plasterboard

Only heat release is contributed by the burner, no fire spread as the wall lining is non-combustible

Temperature development history below the ceiling recorded by K thermocouples

CSIRO Room Corner Fire Experiments

CSIRO wall lining flammability tests in 1999

2400

2400

3600

800Sand box burner

Paper targetRadiometers

Smoke collectionhood

2000

CSIRO Room Corner Fire Experiments

Two test programs:

Case A (ISO Method)HRR=100kW (0-10 minutes)HRR=300kW(10-20 minutes)

Case B (ASTM Method)HRR=40kW (0-5 minutes)HRR=160kW (5-15 minutes)

CSIRO Room Corner Fire Experiments

Heat release rate (HRR) from the fire source, Case A

HRR from case A

0

50

100

150

200

250

300

350

400

0 200 400 600 800 1000 1200Time (sec)

HR

R(k

W)

CFD modelling input

CSIRO test A 1999

CSIRO Room Corner Fire Experiments

Heat release rate (HRR) from the fire source case B

HRR from case B

0

20

40

60

80

100

120

140

160

180

0 200 400 600 800

Time (sec)

HR

R (

kW)

CFD Modeling Input

CSIRO test B 1999

CSIRO Room Corner Fire Experiments

Temperature development history at different locations below the ceiling is recorded

5cm below the ceiling centre

5cm below the ceiling above the burner

10cm below the top of the doorway

Numerical Details

Numerical Details

Input burner fire heat release rate (HRR)

Structured mesh size range 0.02m-0.1m

K-epsilon model for turbulence modeling

Non-constant time step length

Numerical Details

Two kinds of boundary conditions tested: Adiabatic / 0.1m-thick wall included

Two radiation models tested: Radiosity and Immersol radiation model

Two different mesh size test: Coarse mesh and fine mesh

Numerical Details

Non-uniform structured mesh

Fine mesh: 0.02m-0.1m

Coarse mesh: 0.07-0.1m

Numerical Details

Time step length for case A (ISO)

Time 0-30s 30-200s 200-600s

600-630s

630-800s

800-1200s

Step number

60 200 150 60 200 150

Time step length

0.5s 0.85s 2.67s 0.5s 0.85s 2.67s

Numerical Details

Time step length for case B(ASTM)

time 0-30s

30-100s

100-300s

300-330s

330-400s

400-900s

Step number

60 100 100 60 100 200

Time step length

0.5s 0.7s 2.0s 0.5s 0.7s 2.5s

Results and Discussion

Results and Discussion

Hot layer and cold layer

Results and Discussions

Case A

Above the burner and 0.05m below the ceiling

Monitor point above the burner 0.05m below the ceiling

0

200

400

600

800

1000

1200

0 200 400 600 800 1000 1200

Time (Sec)

Tem

per

atu

re (

deg

C)

CFD modelling CSIRO test 1999

Results and Discussions

Case A 0.05m below the ceiling centre

Monitor point 0.05m to the ceiling centre

0

100

200

300

400

500

600

0 200 400 600 800 1000 1200 1400

Time (sec)

Tem

per

atu

re (

deg

C)

CSIRO test 1999 CFD modelling

Results and Discussions

Case A

below the centre of the door 0.1m

Monitor point 0.1m below the top of the door

0

100

200

300

400

500

600

0 200 400 600 800 1000 1200Time (sec)

Tem

per

atu

re (

deg

C)

CFD Modelling

CSIRO test 1999

Results and Discussions

Case A

Comparison of different boundary conditions

Monitor point at 0.1m below the top of the door

0

100

200

300

400

500

600

700

0 200 400 600 800 1000 1200Time (Sec)

Te

mp

era

ture

(d

eg

C)

CSIRO test A

CFD Modeling, CHT

CFD Modeling, adiabatic

Results and Discussions

Case A

Influence of mesh size

Door way temperature predicted using different mesh

0

100

200

300

400

500

0 200 400 600 800 1000 1200

Time (sec)

Te

mp

era

ture

(d

eg

C)

CSIRO Experiment

CFD coarse mesh predicted

CFD fine mesh predicted

Results and Discussions

Case A Comparison of difference radiation model

Results and Discussions

Case BAbove the burner and 0.05m below the ceiling

Monitor point 0.05m below the ceiling above burner case B

0

100

200

300

400

500

600

700

0 200 400 600 800 1000

Time (sec)

Te

mp

era

ture

(d

eg

C)

CFD Modeling CSIRO test B 1999

Results and Discussions

Case B0.05m below the ceiling centre

Monitor point 0.05m below ceiling centre case B

0

50

100

150

200

250

300

350

0 200 400 600 800 1000

Time (sec)

Tem

per

atu

re (

deg

C)

CFD Modelling CSIRO test B, 1999

Results and Discussions

Case B0.1m below the top of the doorway

Monitor point 0.1m below the top of the door for case B

0

50

100

150

200

250

300

0 200 400 600 800 1000

Time (sec)

Tem

per

atu

re (

deg

C)

CFD Modelling CSIRO test B, 1999

Conclusion

Conclusion

Reasonable temperature field can be obtained for the modelling of fire in a test room using PHOENICS software package.

The k-epsilon turbulence model is suitable for the modelling of buoyancy-generated turbulence, if the meshing size is sufficient to resolve the subscale turbulence.

Conclusion

The Radiosity and Immersol radiation approximation models are suitable for the modeling of fire related thermal radiation.

The solid wall should be included into the computation domain as the heat conduction into the wall accounted for a big portion of the total heat transfer, which can influence the CFD modelling accuracy of the indoor gas temperature development.

Acknowledgements

Thanks to Alex, Vince at CSIRO Fire Research

Team for providing the experimental data

Thanks for Dong Chen at CSIRO for help with

programming of PHOENICS user subroutine

Discussion with other team members are

kindly acknowledged