Transcript CFD simulations of a fire in the underground parking of Annecy City Hall H.

CFD simulations of a fire in the
underground parking of Annecy City
Hall
H. BIOLLAY, E. CASALE
SCETAUROUTE Tunneling and underground works division – Annecy, France
J. OUAZZANI
ARCOFLUID, Aix en Provence, France
J.C. HANON
Annecy City Road Division – Annecy, France
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
of the town Hall of Annecy (France).
The car park shape’s is a helical slab which
revolves around a central atrium
A fire start at the bottom of the car park
Phoenics is used to simulate the heat and smoke
evolution
PROBLEM PRESENTATION
Atrium
Natural
ventilation
ducts
Mechanical
ventilation ducts
Exit
Staircases
Level -5
Level -6
17 m
Level -6
Level -5
Natural
ventilation
ducts
Level -2
Mechanical
ventilation
ducts
Slope
34 m
Top view
Front view
Six level car park located in front of the town hall of
Annecy
The car park is underground (the entrance is located at
ground 0)
The CFD Model
Phoenics has been used to simulate such fire
•unsteady, 3D, cylindrical polar coordinates
•VR geometry in cylindrical coordinates
•Turbulence model (k-e RNG model)
•buoyancy phenomena generated by the fire
•Immersol used to simulate radiation
•heat and smoke release - evolution in time
•stairwells, system of ventilation, ventilation shaft,
stationed vehicles, atrium, wall separating the car park
have to be defined
Mesh definition
The numerical grid is composed of 430 000 cells (Figure 1).
Top
view
Vue de
dessus
de cote
SideVue
view
incendie
Fire
Figure 1 : Mesh used for the calculation
Source terms and boundary conditions
Fire represented by a source term of average 5 MW
linear increase of 10 s constant maximum power of heat (5 MW) during 20 mn
Fire source takes into account a density of thermal emission of
1MW/m3
1.1 THE SOURCE TERMS AND THE BOUNDARY CONDITIONS
Vue de dessus
Vue de cote
incendie
External walls at a fixed temperature
(15°C)
Fans are placed at the top of the
ventilation duct (Flow rate extraction of
8.8 m3 /s with a turbulence intensity of
5%)
Outside atmosphere is simulated
wind of 2m/s at 15°C
CONCLUSION
Use of Phoenics code to improve fire protection
in the Annecy town hall car park appears to be a
good choice
Most heat is evacuated through the Atrium
This movement leads to premature invasion of
smoke at higher level but strongly slow downs
the smoke along the helical slab which make it
possible to use the stair-wells with slight
architectural modifications as evacucation gates