H. BIOLLAY, E. CASALE SCETAUROUTE Tunneling and underground works division – Annecy, France

J. OUAZZANIARCOFLUID, Aix en Provence, France

J.C. HANONAnnecy City Road Division – Annecy, France

CFD simulations of a fire in the underground parking of Annecy City

Hall

International PHOENICS Users Conference - Moscow 23-27 sept. 2002

SUMMARY

1 - INTRODUCTION

2 - PROBLEM PRESENTATION

3 - THE CFD MODEL

4 - THE RESULTS

5 - CONCLUSION

International PHOENICS Users Conference - Moscow 23-27 sept. 2002

INTRODUCTION

The problem relates to the Underground car park The problem relates to the Underground car park of the town Hall of Annecy (France). of the town Hall of Annecy (France).

The car park shape’s is a helical slab which The car park shape’s is a helical slab which revolves around a central atriumrevolves around a central atrium

A fire start at the bottom of the car parkA fire start at the bottom of the car park

Phoenics is used to simulate the heat and smoke Phoenics is used to simulate the heat and smoke evolutionevolution

PROBLEM PRESENTATION

Front view

Slope

Exit

Atrium

17 mLevel -6Level -5

Level -2

Level -6Level -5

Natural ventilation

ducts

Natural ventilation

ducts

34 m

Mechanical ventilation ducts

Mechanical ventilation

ducts

Staircases

Top view

Six level car park located in front of the town hall of Six level car park located in front of the town hall of AnnecyAnnecy

The car park is underground (the entrance is located at The car park is underground (the entrance is located at ground 0)ground 0)

The CFD Model

Phoenics has been used to simulate such firePhoenics has been used to simulate such fire

•unsteady, 3D, cylindrical polar coordinatesunsteady, 3D, cylindrical polar coordinates

•VR geometry in cylindrical coordinatesVR geometry in cylindrical coordinates

•Turbulence model (k-Turbulence model (k- RNG model) RNG model)

•buoyancy phenomena generated by the firebuoyancy phenomena generated by the fire

•Immersol used to simulate radiationImmersol used to simulate radiation

•heat and smoke release - evolution in timeheat and smoke release - evolution in time

•stairwells, system of ventilation, ventilation shaft, stairwells, system of ventilation, ventilation shaft, stationed vehicles, atrium, wall separating the car park stationed vehicles, atrium, wall separating the car park have to be definedhave to be defined

The nu m erical grid is co mposed o f 430 000 cells (F igure 1 ).

Vue de dessus

Vue de cote

incendie

F igure 1 : M esh used fo r the calcu lation

S ide vie w

F ire

Top vie w

Mesh definition

1.1 TH E SO URCE TE RM S AND TH E B O UNDARY CO NDITIO NS

Vue de dessus

Vue de cote

incendie

Source terms and boundary conditions

Fire represented by a source term of average 5 MWFire represented by a source term of average 5 MW

linear increase of 10 s - linear increase of 10 s -

constant maximum power of heat (5 MW) during 20 mnconstant maximum power of heat (5 MW) during 20 mn

Fire source takes into account a density of thermal emission of Fire source takes into account a density of thermal emission of 1MW/m1MW/m33

External walls at a fixed temperature External walls at a fixed temperature (15°C)(15°C)

Fans are placed at the top of the Fans are placed at the top of the ventilation duct (Flow rate extraction of ventilation duct (Flow rate extraction of 8.8 m8.8 m33 /s with a turbulence intensity of /s with a turbulence intensity of 5%)5%)

Outside atmosphere is simulated Outside atmosphere is simulated

wind of 2m/s at 15°Cwind of 2m/s at 15°C

CONCLUSION

Use of Phoenics code to improve fire protection Use of Phoenics code to improve fire protection in the Annecy town hall car park appears to be a in the Annecy town hall car park appears to be a good choicegood choice

Most heat is evacuated through the AtriumMost heat is evacuated through the Atrium

This movement leads to premature invasion of This movement leads to premature invasion of smoke at higher level but strongly slow downs smoke at higher level but strongly slow downs the smoke along the helical slab which make it the smoke along the helical slab which make it possible to use the stair-wells with slight possible to use the stair-wells with slight architectural modifications as evacucation gatesarchitectural modifications as evacucation gates