Evaluation of PHOENICS CFD fire model against room corner fire experiments

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Evaluation of PHOENICS CFD fire model against
room corner fire experiments

• Yunlong Liu and Vivek Apte

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Presentation content

• Introduction
• CSIRO Room Corner Fire Experiments
• Numerical Details
• Results and Discussion
• Conclusion

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• Introduction

4
Introduction

• Accidental fire loss is big
• Experimental method
• Numerical method
• Design fire concept

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Introduction

• Implementation of Design Fire - Stage 1
• Validate software Packages
• Input Structure geometry, experimentally measured
  HRR, smoke RR into the CFD Model
• Output 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

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Introduction

• Implementation of Design Fire - Stage 2
• Find the design fire
• Input the location of the fire source, turbulence
  model, BC, radiation model, mesh layout
• Output HRR, Smoke RR, Temperature field, smoke
  concentration field
• What is needed
• Experimentally measured Temperature field and
• smoke concentration field needed for validation

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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, BC
• Output 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
  and
• BC from stage 1, HRR and smoke RR from stage 2

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Introduction

• Software platform
• Zone model
• CFAST, BranzFire
• Field model (CFD model)
• CFX, FLUENT, PHOENICS, FDS, SmartFire

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• CSIRO Room Corner Fire Experiments

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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

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CSIRO Room Corner Fire Experiments

• CSIRO wall lining flammability tests in 1999

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CSIRO Room Corner Fire Experiments

• Two test programs
• Case A (ISO Method)
• HRR100kW (0-10 minutes)
• HRR300kW(10-20 minutes)
• Case B (ASTM Method)
• HRR40kW (0-5 minutes)
• HRR160kW (5-15 minutes)

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CSIRO Room Corner Fire Experiments

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

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CSIRO Room Corner Fire Experiments

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

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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

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• Numerical Details

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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

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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

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Numerical Details

• Non-uniform structured mesh
• Fine mesh
• 0.02m-0.1m
• Coarse mesh
• 0.07-0.1m

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Numerical Details
Time step length for case A (ISO)
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Numerical Details
Time step length for case B(ASTM)
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• Results and Discussion

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Results and Discussion

• Hot layer and cold layer

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Results and Discussions

• Case A
• Above the burner and 0.05m below the ceiling

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Results and Discussions

• Case A
• 0.05m below the ceiling centre

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Results and Discussions

• Case A
• below the centre of the door 0.1m

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Results and Discussions

• Case A
• Comparison of different boundary conditions

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Results and Discussions

• Case A
• Influence of mesh size

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Results and Discussions

• Case A
• Comparison of difference radiation model

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Results and Discussions

• Case B
• Above the burner and 0.05m below the ceiling

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Results and Discussions

• Case B
• 0.05m below the ceiling centre

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Results and Discussions

• Case B
• 0.1m below the top of the doorway

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• Conclusion

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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.

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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.

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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