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Evaluation of PHOENICS CFD fire model against room corner fire experiments

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

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Evaluation of PHOENICS CFD fire model against room corner fire experiments

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  1. Evaluation of PHOENICS CFD fire model against room corner fire experiments Yunlong Liu and Vivek Apte

  2. Presentation content • Introduction • CSIRO Room Corner Fire Experiments • Numerical Details • Results and Discussion • Conclusion

  3. Introduction

  4. Introduction • Accidental fire loss is big • Experimental method • Numerical method • Design fire concept

  5. 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

  6. 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

  7. 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

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

  9. CSIRO Room Corner Fire Experiments

  10. 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

  11. CSIRO Room Corner Fire Experiments CSIRO wall lining flammability tests in 1999

  12. 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)

  13. CSIRO Room Corner Fire Experiments Heat release rate (HRR) from the fire source, Case A

  14. CSIRO Room Corner Fire Experiments Heat release rate (HRR) from the fire source case B

  15. 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

  16. Numerical Details

  17. 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

  18. 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

  19. Numerical Details Non-uniform structured mesh • Fine mesh: 0.02m-0.1m • Coarse mesh: 0.07-0.1m

  20. Numerical Details Time step length for case A (ISO)

  21. Numerical Details Time step length for case B(ASTM)

  22. Results and Discussion

  23. Results and Discussion • Hot layer and cold layer

  24. Results and Discussions Case A Above the burner and 0.05m below the ceiling

  25. Results and Discussions Case A • 0.05m below the ceiling centre

  26. Results and Discussions Case A below the centre of the door 0.1m

  27. Results and Discussions Case A • Comparison of different boundary conditions

  28. Results and Discussions Case A Influence of mesh size

  29. Results and Discussions Case A • Comparison of difference radiation model

  30. Results and Discussions Case B Above the burner and 0.05m below the ceiling

  31. Results and Discussions Case B 0.05m below the ceiling centre

  32. Results and Discussions Case B 0.1m below the top of the doorway

  33. Conclusion

  34. 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.

  35. 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.

  36. 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

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