Validating FDS Against a Large Scale Fire Test Paul Blake - PowerPoint PPT Presentation

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 • About me… • MSc research program completed in 2015. • Part-time student Ph.D. University of Leeds, UK. • Altor Fire Paul Blake- University of Leeds. Fire and Evacuation Modelling 05/12/2018 2 Technical Conference 2018

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

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

A Full Height Fire… • External floor-to-floor travel • Internal fire spread: ineffectual compartmentalisation • Combustible external surfaces The Tall Building Fire Safety Network Paul Blake- University of Leeds. Fire and Evacuation Modelling 05/12/2018 5 Technical Conference 2018

External Walling Systems (Facades) Paul Blake- University of Leeds. Fire and Evacuation Modelling 05/12/2018 6 Technical Conference 2018

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 Paul Blake- University of Leeds. Fire and Evacuation Modelling 05/12/2018 7 Technical Conference 2018

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 200 0 C above ambient. • A failure occurs due to external fire spread is determined when an external thermocouple at Level 2 exceeds 600 0 C 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 600 0 C above ambient temperature for at least 30 seconds within 15 minutes of the fire spread time. Paul Blake- University of Leeds. Fire and Evacuation Modelling 05/12/2018 8 Technical Conference 2018

05/12/2018 9

BRE-DCLG Test-1 Results Polyethylene (PE) cladding core Polyisocyanurate (PIR) insulation Parameter Result 18.4 0 C T s Start temperature t s Start time 130 seconds after the ignition of the crib 813.9 0 C at 390 seconds after t s Peak temperature/time at Level 2, External 410.4 0 C at 380 seconds after t s Peak temperature/time at Level 2, Cavity 218.4 0 C at 380 seconds after t s Peak temperature/time at Level 2, Insulation Paul Blake- University of Leeds. Fire and Evacuation Modelling 05/12/2018 10 Technical Conference 2018

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. Paul Blake- University of Leeds. Fire and Evacuation Modelling 05/12/2018 11 Technical Conference 2018

ሶ Conductive Heat Flux in FDS (Eq1) " = ℎ(𝑈 𝑟 𝑑 𝑕 − 𝑈 𝑥 ) Where; h is the convective heat transfer coefficient T g is the gas temperature T w is the surface wall temperature. Paul Blake- University of Leeds. Fire and Evacuation Modelling 05/12/2018 12 Technical Conference 2018

ሶ Conductive Heat Flux in FDS (Eq2) ) Where the radiation shape is unity, the radiative heat flux is given by: " = 𝜁𝜏(𝑈 4 − 𝑈 4 ) 𝑟 𝑠 𝑥 𝑏 Where: • 𝜁 = emissivity • 𝜏 = Stefan-Boltzmann constant (5.670x10-8 W/m 2 ∙ K 4 ) • 𝑈 𝑥 = wall temperature • 𝑈 𝑏 = ambient temperature Paul Blake- University of Leeds. Fire and Evacuation Modelling 05/12/2018 13 Technical Conference 2018

Conductive Heat Flux in FDS (Eq3) 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) Paul Blake- University of Leeds. Fire and Evacuation Modelling 05/12/2018 14 Technical Conference 2018

Materials, Layers and Surfaces • Void: Air gap, open to heat Material Depth (mm) fluxes. Cladding Aluminium 0.5 • Exposed: Heat can be conducted Polyethylene (PE) 3.0 through the material. Aluminium 0.5 • Insulated: No heat is lost from Insulation layer the rear of the material. Polyisocyanurate (PIR) 80 Air 80 Paul Blake- University of Leeds. Fire and Evacuation Modelling 05/12/2018 15 Technical Conference 2018

Most reactive Next most reactive Against the three surface backings Paul Blake- University of Leeds. Fire and Evacuation Modelling 05/12/2018 17 Technical Conference 2018

BRE-DCLG Test-1 Results Polyethylene (PE) cladding core Polyisocyanurate (PIR) insulation Parameter Result 18.4 0 C T s Start temperature t s Start time 130 seconds after the ignition of the crib 813.9 0 C at 390 seconds after t s Peak temperature/time at Level 2, External 410.4 0 C at 380 seconds after t s Peak temperature/time at Level 2, Cavity 218.4 0 C at 380 seconds after t s Peak temperature/time at Level 2, Insulation Paul Blake- University of Leeds. Fire and Evacuation Modelling 05/12/2018 18 Technical Conference 2018

Level 2 – External: 1029-C Level 2 External 1029-C 900.00 800.00 700.00 600.00 Temperature (C) 500.00 400.00 300.00 200.00 100.00 0.00 0.00 100.00 200.00 300.00 400.00 500.00 600.00 Time (s) Void 1029-C Exposed 1029-C Insulated 1029-C BRE-CLG 1029-C Paul Blake- University of Leeds. Fire and Evacuation Modelling 05/12/2018 19 Technical Conference 2018

Level 2 – External: 1026-C Level 2 External 1026-C 800.00 700.00 600.00 500.00 400.00 300.00 200.00 100.00 0.00 0.00 100.00 200.00 300.00 400.00 500.00 600.00 BRE-CLG 1026--C Void 1026-C Exposed 1026-C Insulated 1026-C Paul Blake- University of Leeds. Fire and Evacuation Modelling 05/12/2018 20 Technical Conference 2018

Level 2- Cavity: 1028-C Level 2 1028-C Cavity 450.00 400.00 350.00 300.00 Temperature (C) 250.00 200.00 150.00 100.00 50.00 0.00 0.00 100.00 200.00 300.00 400.00 500.00 600.00 700.00 Time (s) Void 1028-C Exposed 1028-C Insulated 1028-C BRE-CLG 1028-C Paul Blake- University of Leeds. Fire and Evacuation Modelling 05/12/2018 21 Technical Conference 2018

Level 2- Cavity: 1025-C Level 2 Cavity 1025-C 400.00 350.00 300.00 250.00 Temperature (C) 200.00 150.00 100.00 50.00 0.00 0.00 100.00 200.00 300.00 400.00 500.00 600.00 700.00 Time (s) BRE-CLG 1025-C Void 1025-C Exposed 1025-C Insulated 1025-C Paul Blake- University of Leeds. Fire and Evacuation Modelling 05/12/2018 22 Technical Conference 2018

Level 2- Insulation: 1027-C Level 2 Insulation 1027-C 250.00 200.00 Temperature (C) 150.00 100.00 50.00 0.00 0.00 100.00 200.00 300.00 400.00 500.00 600.00 Time (s) Void 1027-C Exposed 1027-C Insulated 1027-C BRE-CLG 1027-C Paul Blake- University of Leeds. Fire and Evacuation Modelling 05/12/2018 23 Technical Conference 2018

Level 2- Insulation: 1024-C Level 2 Insulation 1024-C 300 250 200 Temperature (C) 150 100 50 0 0.00 100.00 200.00 300.00 400.00 500.00 600.00 Time (s) BRE=CLG 1024-C Void 1024-C Exposed 1024-C Insulated 1024-C Paul Blake- University of Leeds. Fire and Evacuation Modelling 05/12/2018 24 Technical Conference 2018

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 Paul Blake- University of Leeds. Fire and Evacuation Modelling 05/12/2018 25 Technical Conference 2018

Any questions? Thank you 26