CFD Applications of PHOENICS on Building Environment and Fire Safety Design

1. 1 CFD Applications of PHOENICS on Building Environment and Fire Safety Design Qian Wang, PhD, CFD Specialist Kenneth Ma, Senior Associate Micael Lundqvist, Senior Fire Engineer Ove Arup Pty Ltd Level 10, 201 Kent Street, Sydney NSW 2000, Australia

2. 2 Abstract ARUP has been using PHOENICS for many years to deal with various CFD modellings in building thermal comfort design, indoor environment, fire safety control, etc. and has gained good results recognised by the clients. This paper summarises some selected CFD studies of normal & emergency ventilation controls. Software PHEONICS PC version 3.3 & 3.4 Computers COMPAQWorkStation Pentium 3/800MHz & Pentium 4/1.6GHz INTRRODUCTION

3. 3 • Project Type • Urban underground railway station with connecting tunnel to the ground level, heavily occupied with diesel trains • CFD Objectives • Platform: thermal comfort & air quality . • Tunnel: smoke ventilation control during emergency fire in the connecting tunnel. Description of Project

4. 4 Diagram Description of Project

5. 5 • CFD Tasks & Outcomes • To provide all detailed information to support the final design of mechanical ventilation system. • Temperature, air velocity, concentration of pollutant gases (CO, CO2, NO, etc) in winter & summer seasons. Station Normal Ventilation

6. 6 CFD Domain Station Normal Ventilation

7. 7 CFD Input Conditions Station Normal Ventilation

8. Velocity Vector 8 Station Normal Ventilation - winter

9. 9 Station Normal Ventilation - winter

10. Velocity Vectors 10 Station Normal Ventilation - summer

11. Velocity Vectors 11 Station Normal Ventilation - summer

12. 12 Summary • Winter • Allowable concentration of CO (25ppm) is acceptable. • Gas fume is accumulating near ceiling. • Summer • Well mixed fluid domain. • Containment materials may be driven towards the platforms . • Hot layer within T > 30°C is broader and thicker, may result in discomfort to the passengers. • The 0.082% CO level (25ppm) is quite close to the platforms – greater ventilation capacity is required. Station Normal Ventilation

13. 13 • CFD Tasks & Outcomes • To evaluate the smoke control policy during emergency fires in the sloped tunnel (450m x 8.9m x 6m). • Transient air velocities, temperatures and smoke concentrations. • Behaviours of backlayering of smoke towards station platform. Tunnel Fire Smoke Control

14. 14 Tunnel Fire Smoke Control

15. 15 Train Fire in Entry Tunnel Entrance of Ground Level Ventilation Shaft 8.9m 6m Jet Fan Fire Source Train Ventilation Shaft Connection to Station Tunnel Fire Smoke Control

16. 16 Fire Scenario Description 1 - Carriage Fire 'worst credible' fire breaking out inside a train that is stopping in the tunnel between the two vent shafts. Assumed to be an exponentially ‘fast’ growing fire with the maximum fire size 15MW, as a fully developed carriage fire. 2 - Suppressed Diesel Fire 'worst credible‘ scenario for a fire outside a stopped train between the two vent shafts and is leaking diesel. The fire is assumed to be a ‘fast’ (0.047kW/s²) growing fire, which is suppressed upon activation of the foam suppression system at track level. 3 - Unsuppressed Diesel Fire This fire scenario is a sensitivity analysis of the diesel fire outside the carriage (Scenario 2) in the event of failure of the foam suppression system. The fire therefore continuos to grow to its maximum size 40MW, involving both the diesel and a carriage. Fire Safety Design Criteria • T < 200°C if hot layer is above 1.5m from floor level. • T <60°C if hot layer is below 1.5m and/or the visibility not be less than 6m (ie the optical density should not exceed 0.14m-1). Tunnel Fire Smoke Control

17. 17 Q [MW] d 40 20 4.22 0 Scenario 1-- abc Scenario 2-- abe Scenario 3-- abcd Fire starts All jet fans stop F1 operates: 180m3/s c b e a 0 3 4 5 6 10 15.5 t [min] Tunnel Fire Smoke Control

18. 18 Temperature Concentration Tunnel Fire Smoke Control - Scenario 1

19. 19 Temperature Backlayering Distance Concentration Tunnel Fire Smoke Control - Scenario 3

20. 20 Double click the image to play ! Tunnel Fire Smoke Control

21. Summary 21 It is proved that the design smoke control/ventilation system during different fires will be able to provide a reasonable fire safety condition according to the calculated internal temperature, CO concentration levels. Conclusions of PHOENICS PHOENICS applications on building internal air quality control and emergency fire smoke control strategy have been carried out. Very detailed thermal and fluid behaviours of internal air have been analysed, which either identified the efficiency of the ventilation systems or provided the optimisation to the design features. All these results prove that PHOENICS can deal with very broad fluid dynamic modelling, and is the most cost effective tool in professional engineering consultant services. Tunnel Fire Smoke Control