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Validating FDS Against a Large Scale Fire Test Paul Blake (pm08pb@leeds.ac.uk) University of Leeds Altor Fire Limited Paul Blake- University of Leeds. Fire and Evacuation Modelling 05/12/2018 1 Technical Conference 2018 Introduction

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Validating FDS Against a Large Scale Fire Test

Paul Blake (pm08pb@leeds.ac.uk) University of Leeds Altor Fire Limited

05/12/2018 Paul Blake- University of Leeds. Fire and Evacuation Modelling Technical Conference 2018 1

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SLIDE 2

Introduction

  • About me…
  • MSc research program completed in 2015.
  • Part-time student Ph.D. University of Leeds, UK.
  • Altor Fire

05/12/2018 Paul Blake- University of Leeds. Fire and Evacuation Modelling Technical Conference 2018 2

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SLIDE 3

Today…

  • Replicate a full scale fire test in FDS

6.2.0

  • Compare the material backing

functions in FDS 6.2.0;

  • Void
  • Exposed
  • Insulated

05/12/2018 Paul Blake- University of Leeds. Fire and Evacuation Modelling Technical Conference 2018 3

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SLIDE 4

My ongoing research aims……

  • Fire testing of external walling materials, conducted at the University of

Leeds, then replicate the test results in FDS 6.2.0.

  • Quantify the Heat Release Rate (HRR) of a full height fire. Determining if

there is a correlation between the visible flame height of a fire height fire and the heat release rate.

  • Use CFD (FDS) to accurately model the conditions that are evident during a

full height fire.

  • Assess the current fire test standards for external walling systems against

actual fire conditions in tall buildings.

  • Design evacuation models that can be applied to the conditions of a full

height fire at the building including a simultaneous evacuation of buildings not designed for such a procedure.

05/12/2018 Paul Blake- University of Leeds. Fire and Evacuation Modelling Technical Conference 2018 4

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A Full Height Fire…

  • External floor-to-floor travel
  • Internal fire spread: ineffectual

compartmentalisation

  • Combustible external surfaces

The Tall Building Fire Safety Network

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SLIDE 6

External Walling Systems (Facades)

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SLIDE 7

BS8414-1:2015 Full scale fire test

Fire performance of external cladding

  • systems. Test method for non-loadbearing

external cladding systems applied to the masonry face of a building.

  • Main face (>2600mm x >6000mm)
  • Wing face (>1500mm x >6000mm)
  • Combustion chamber (2000mm)
  • Wood crib fire
  • Level 1 and Level 2 thermocouples
  • 1800 seconds duration of test
  • Narrative taken

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Test criteria….

The performance criteria and for the failure of a test is defined in BR 135; “Fire performance of external thermal insulation for walls of multi-storey buildings, third edition”. and is as follows;

  • The fire spread start time defined as the time when the temperature

measured by an external thermocouple as Level 1 exceeds 2000C above ambient.

  • A failure occurs due to external fire spread is determined when an external

thermocouple at Level 2 exceeds 6000C for at least 30 seconds within 15 minutes of the fire spread start time.

  • A failure due to internal fire spread is determined when any internal

thermocouple at Level 2 exceeds 6000C above ambient temperature for at least 30 seconds within 15 minutes of the fire spread time.

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05/12/2018 9

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BRE-DCLG Test-1 Results

Parameter Result Ts Start temperature 18.40C ts Start time 130 seconds after the ignition of the crib Peak temperature/time at Level 2, External 813.90C at 390 seconds after ts Peak temperature/time at Level 2, Cavity 410.40C at 380 seconds after ts Peak temperature/time at Level 2, Insulation 218.40C at 380 seconds after ts

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Polyethylene (PE) cladding core Polyisocyanurate (PIR) insulation

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SLIDE 11

Setup in FDS

  • Thermocouples.
  • Inside wall temperature devices.
  • Heat Release Rate Per Unit Area:

2100kW.

  • Mesh size is defined by the

“EXPOSED” function.

  • Surface front adjusted.

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Conductive Heat Flux in FDS (Eq1)

ሶ 𝑟𝑑

" = ℎ(𝑈 𝑕 − 𝑈 𝑥)

Where; h is the convective heat transfer coefficient Tg is the gas temperature Tw is the surface wall temperature.

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Where the radiation shape is unity, the radiative heat flux is given by: ሶ 𝑟𝑠

" = 𝜁𝜏(𝑈 𝑥 4 − 𝑈 𝑏 4)

Where:

  • 𝜁= emissivity
  • 𝜏= Stefan-Boltzmann constant (5.670x10-8 W/m2∙K4)
  • 𝑈

𝑥= wall temperature

  • 𝑈

𝑏= ambient temperature

Conductive Heat Flux in FDS (Eq2))

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SLIDE 14

Conductive Heat Flux in FDS (Eq3)

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For steady state heat conduction through a uniform material with no internal heat generation, the conductive heat flux reads;is given by

Where: 𝑙= conductivity 𝑢ℎ𝑗𝑑𝑙= thickness of the material 𝑈

𝑐𝑏𝑑𝑙= wall temperature (back)

𝑈

𝑔𝑠𝑝𝑜𝑢= wall temperature (front)

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Materials, Layers and Surfaces

Material Depth (mm) Cladding Aluminium 0.5 Polyethylene (PE) 3.0 Aluminium 0.5 Insulation layer Polyisocyanurate (PIR) 80 Air 80

  • Void: Air gap, open to heat

fluxes.

  • Exposed: Heat can be conducted

through the material.

  • Insulated: No heat is lost from

the rear of the material.

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Most reactive Next most reactive Against the three surface backings

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BRE-DCLG Test-1 Results

Parameter Result Ts Start temperature 18.40C ts Start time 130 seconds after the ignition of the crib Peak temperature/time at Level 2, External 813.90C at 390 seconds after ts Peak temperature/time at Level 2, Cavity 410.40C at 380 seconds after ts Peak temperature/time at Level 2, Insulation 218.40C at 380 seconds after ts

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Polyethylene (PE) cladding core Polyisocyanurate (PIR) insulation

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Level 2– External: 1029-C

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0.00 100.00 200.00 300.00 400.00 500.00 600.00 700.00 800.00 900.00 0.00 100.00 200.00 300.00 400.00 500.00 600.00

Temperature (C) Time (s)

Level 2 External 1029-C

Void 1029-C Exposed 1029-C Insulated 1029-C BRE-CLG 1029-C

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SLIDE 19

Level 2– External: 1026-C

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0.00 100.00 200.00 300.00 400.00 500.00 600.00 700.00 800.00 0.00 100.00 200.00 300.00 400.00 500.00 600.00

Level 2 External 1026-C

BRE-CLG 1026--C Void 1026-C Exposed 1026-C Insulated 1026-C

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Level 2- Cavity: 1028-C

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0.00 50.00 100.00 150.00 200.00 250.00 300.00 350.00 400.00 450.00 0.00 100.00 200.00 300.00 400.00 500.00 600.00 700.00

Temperature (C) Time (s)

Level 2 1028-C Cavity

Void 1028-C Exposed 1028-C Insulated 1028-C BRE-CLG 1028-C

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Level 2- Cavity: 1025-C

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0.00 50.00 100.00 150.00 200.00 250.00 300.00 350.00 400.00 0.00 100.00 200.00 300.00 400.00 500.00 600.00 700.00

Temperature (C) Time (s)

Level 2 Cavity 1025-C

BRE-CLG 1025-C Void 1025-C Exposed 1025-C Insulated 1025-C

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Level 2- Insulation: 1027-C

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0.00 50.00 100.00 150.00 200.00 250.00 0.00 100.00 200.00 300.00 400.00 500.00 600.00

Temperature (C) Time (s)

Level 2 Insulation 1027-C

Void 1027-C Exposed 1027-C Insulated 1027-C BRE-CLG 1027-C

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Level 2- Insulation: 1024-C

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50 100 150 200 250 300 0.00 100.00 200.00 300.00 400.00 500.00 600.00

Temperature (C) Time (s)

Level 2 Insulation 1024-C

BRE=CLG 1024-C Void 1024-C Exposed 1024-C Insulated 1024-C

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Conclusion & Progression

  • The result of the modelling is based on a single test.
  • Modelling against a fixed temperature
  • Will complete the BRE-DCLG test reports
  • Not all Polyethylene's are created equal.
  • Adjustments to the ramp-up time.
  • The insulation and cavities are hard to replicate post test.
  • Void and Exposed material backing.
  • Air channels

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Thank you

Any questions?

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