CFD Applications of PHOENICS CFD Applications of PHOENICS on Building Environment and Fire on Building Environment and Fire Safety DesignSafety Design

1

Qian Wang, PhD, CFD Specialist Qian Wang, PhD, CFD Specialist Kenneth Ma, Senior Associate Kenneth Ma, Senior Associate Micael Lundqvist, Senior Fire EngineerMicael Lundqvist, Senior Fire Engineer

Ove Arup Pty Ltd Ove Arup Pty Ltd Level 10, 201 Kent Street, Sydney Level 10, 201 Kent Street, Sydney NSW 2000, AustraliaNSW 2000, Australia

2

SoftwareSoftware

PHEONICSPHEONICS PC version 3.3 & 3.4 PC version 3.3 & 3.4

ComputersComputers

COMPAQCOMPAQ WorkStation Pentium 3/800MHzWorkStation Pentium 3/800MHz

& Pentium 4/1.6GHz& Pentium 4/1.6GHz

INTRRODUCTIONINTRRODUCTION

AbstractAbstract

ARUP has been using PHOENICS for many years to ARUP has been using PHOENICS for many years to deal with various CFD modellings in deal with various CFD modellings in building thermal building thermal comfort designcomfort design, , indoor environmentindoor environment, , fire safety controlfire safety control, , etc. and has gained good results recognised by the etc. and has gained good results recognised by the clients. This paper summarises some selected CFD clients. This paper summarises some selected CFD studies of normal & emergency ventilation controls.studies of normal & emergency ventilation controls.

3

Description of ProjectDescription of Project

Project Type Project Type

Urban underground railway station with Urban underground railway station with connecting tunnel to the ground level, connecting tunnel to the ground level, heavily heavily occupied with diesel trainsoccupied with diesel trains

CFD ObjectivesCFD Objectives

1.1. Platform: Platform: thermal comfort & air quality .thermal comfort & air quality .

2.2. Tunnel:Tunnel: smoke ventilation control smoke ventilation control during emergency fire in during emergency fire in

the the connecting tunnel.connecting tunnel.

Diagram Diagram

Description of ProjectDescription of Project

4

5

CFD Tasks & OutcomesCFD Tasks & Outcomes

• To provide all detailed information to To provide all detailed information to support the final design of mechanical support the final design of mechanical ventilation system.ventilation system.

• Temperature, air velocity, concentration Temperature, air velocity, concentration of pollutant gases (CO, COof pollutant gases (CO, CO22, NO, etc) in , NO, etc) in

winter & summer seasons.winter & summer seasons.

Station Normal Station Normal VentilationVentilation

CFD DomainCFD Domain

6

Station Normal Station Normal VentilationVentilation

7CFD Input ConditionsCFD Input Conditions

Station Normal Station Normal VentilationVentilation

 

Main Settings DescriptionsTotal cells X=73, Y=138, Z=36Turbulance model Standard K-e (KEMODL)Differencing scheme HYBRIDGlobal convergence criterion 0.01%

Reference temperature 15 oC in winter, 27

oC in summer

Boundary effect on turbulence OffCoefficient for auto wall functions LOG-LAWTotal number of iteration 2000Domain material 40 dummy fluid (self-edited)

density 1.18viscosity 1.83E-05

specific heat 1005conductivity 0.026

Station Normal Ventilation - winterStation Normal Ventilation - winter

 

8Velocity Vector

Station Normal Ventilation - winterStation Normal Ventilation - winter

 

9

Station Normal Ventilation - Station Normal Ventilation - summersummer

 

Velocity Vectors 10

Station Normal Ventilation - Station Normal Ventilation - summersummer

 

Velocity Vectors 11

Station Normal VentilationStation Normal Ventilation

 

12SummarySummary

WinterWinter

• Allowable concentration of CO (25ppm) is acceptable. Allowable concentration of CO (25ppm) is acceptable.

• Gas fume is accumulating near ceiling.Gas fume is accumulating near ceiling.

SummerSummer

• Well mixed fluid domain.Well mixed fluid domain.

• Containment materials may be driven towards the Containment materials may be driven towards the platforms .platforms .

• Hot layer within T > 30°C is broader and thicker, may Hot layer within T > 30°C is broader and thicker, may result in discomfort to the passengers. result in discomfort to the passengers.

• The 0.082% CO level (25ppm) is quite close to the The 0.082% CO level (25ppm) is quite close to the platforms – greater ventilation capacity is required.platforms – greater ventilation capacity is required.

13

CFD Tasks & OutcomesCFD Tasks & Outcomes

• To evaluate the smoke control policy To evaluate the smoke control policy during emergency fires in the sloped during emergency fires in the sloped tunnel (450m x 8.9m x 6m)tunnel (450m x 8.9m x 6m). .

• Transient air velocities, temperatures Transient air velocities, temperatures and smoke concentrations.and smoke concentrations.

• Behaviours of backlayering of smoke Behaviours of backlayering of smoke towards station platform.towards station platform.

Tunnel Fire Smoke ControlTunnel Fire Smoke Control

Tunnel Fire Smoke ControlTunnel Fire Smoke Control

- 1 1 0 2 0 4 0 8 0 1 2 0 2 6 0 4 2 6 m

1 . 4 3 %

2 %

P o r t a l

1 1 . 3 2

2 . 00 . 0

6 m 6 m E x h a u s t S h a f t

6 m 6 m E x h a u s t S h a f t12.8

810

.19

11.4

8.7

5 . 3 2S t a t i o ns i d e

Pri

tom

art P

lace

Tin

ley

Str

eet

1 1 01 8 0

3 2 03 9 0

X

Y

T r a i n o n f i r e

0 . 0

J e t F a n

E x h a u s tF a n F 1

8 . 9 m

6m

J e t f a n s ( J F 1 ~ J F 3 )J e t f a n s ( J F 4 ~ J F 5 )E x h a u s t s h a f t s

T r a i n s i z eF i r e s i z e

F i r e s o u r c e r e g i o n

7 1 0 , L = 3 2 9 0 1 1 2 0 , L = 3 5 0 06 m 6 mC a p a c i t y : 1 8 0 m 3 / s ( 5 m / s ) e a c h2 0 m ( L ) 2 . 5 m ( W ) 3 . 8 m ( H ) 6 ( C a r s ) , L = 1 2 0 mT i m e - d e p e n d e n t f i r e h e a t r e l e a s e r a t e w i t h i n m a x i m u m v a l u e u p t o4 0 M W i n w h i c h 4 0 M W 6 5 % = 2 6 M W c o n t r i b u t e s t o t h e t h e r m a l f u m eI n c r e a s e s a l o n g w i t h t h e h e a t r e l e a s e r a t e o f f i r e b a s e d o n 1 . 5 M W / m 2

E x h a u s tF a n F 2

J F 1

J F 3

J F 4

J F 2

J F 5

7 1F i r e c e n t r e

4 0

14

Ventilation Shaft

Ventilation Shaft

Fire Source

Entrance of Entrance of Ground LevelGround Level

Connection Connection to Station to Station

Jet Fan

Train

Train Fire in Entry TunnelTrain Fire in Entry Tunnel

8.9m

6m

Tunnel Fire Smoke ControlTunnel Fire Smoke Control

15

Fire

16

Tunnel Fire Smoke ControlTunnel Fire Smoke Control

•T < T < 200°C200°C if hot layer is above 1.5m from floor level. if hot layer is above 1.5m from floor level.

•T <T <60°C60°C if hot layer is below 1.5m and/or the visibility not be less if hot layer is below 1.5m and/or the visibility not be less than than 6m6m (ie the optical density should not exceed 0.14m (ie the optical density should not exceed 0.14m-1-1).).

Fire Safety Design CriteriaFire Safety Design Criteria

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.

0 3 4 5 6 10 15.5

40

20

4.22

0

t t [min][min]

Q [MW]Q [MW]

a

b

d

e

Scenario 1-- abc Scenario 2-- abe Scenario 3-- abcd

Fire startsFire starts

All jet fans stopAll jet fans stop

F1 operates: 180mF1 operates: 180m33/s/s

271081.7 tQ

c

17

Tunnel Fire Smoke ControlTunnel Fire Smoke Control

18

Tunnel Fire Smoke Control - Tunnel Fire Smoke Control - Scenario 1Scenario 1

TemperatureTemperature ConcentrationConcentration

19

Tunnel Fire Smoke Control - Tunnel Fire Smoke Control - Scenario 3Scenario 3

TemperatureTemperature

ConcentrationConcentration0

10

20

30

40

50

60

70

80

90

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15

Time after fire ignation [min]

Ba

ck

lay

eri

ng

dis

tan

ce

fro

m F

ire

s

ou

rce

[m

]

Backlayering Backlayering DistanceDistance

20

Double click the image to play !Double click the image to play !

Tunnel Fire Smoke ControlTunnel Fire Smoke Control

21

Tunnel Fire Smoke ControlTunnel Fire Smoke Control

SummarySummaryIt 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 PHOENICSConclusions of PHOENICSPHOENICS 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.