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Experimental and numerical studiesto assess the benefits of water mist system
in Mont-Blanc tunnelSylvain DESANGHERE1, Eric CESMAT1, David GIULIANI2
(1) Lombardi (France), (2) GEIE TMB (France)
More information : [email protected]
1. OVERVIEWStudy of the use of water mist system in theMont-Blanc tunnel :
Bibliographic review of existing fixed fire-fighting systems (FFS)
Experimental performance assessment ofseveral types of FFS at scale 0.8
Numerical simulations to evaluate the in-teraction of water mist system with existingsafety equipment and procedures
2. EXPERIMENTAL CAMPAIGN15 fire tests carried out in the TST tunnel testsfacility (San Pedro, Spain) [1, 2].
3 FFS technologies : SPK, low-pressurewater mist, high-pressure water mist
2 fire load compositions: 30 MW wood, 50MW wood and gasoil
2 activation strategies : as fire detected,at t = 7 min (firefighters arrival)
Monitoring of temperature, velocity, gascomposition, heat flux, etc.
22 m3/s 22 m3/s 22 m3/s 22 m3/s
~ 2 m/s ~ 1,5 m/s ~ 1 m/s ~ 0,5 m/s ~ 0 m/s
F
N025
N050
N075
N100
N125
N150
S175
S150
S125
S100
S075
S050
S025 N175
TST jets fans
SOUTH NORTH
Spraying
S010 N010
High-pressure water mist system provides thebest performance (gas cooling and firesuppression).
3. NUMERICAL STUDYWorking approach
CFD modeling using FDS (NIST, USA) [3]Spray parameters validation by simulating
6 experimental testsExtensive use of FDS to simulate realistic
fire scenariosRosin-Rammler/log-normal droplets sizedistribution:
F(D) =
1√2π
∫ d
0
1σd ′ exp
(−[ln(d ′/dm)]
2
2σ2
)dd ′ (d ≤ dm)
1 − exp(−0.693
(ddm
)γ)(d > dm)
0
10
20
30
40
50
60
70
80
90
100
f(d)
x 1
03
d (µm)
0
10
20
30
40
50
60
70
80
90
100
F(d)
d (µm)
Comparison with experimental data
0
100
200
300
400
500
600
700
800
0 1 2 3 4 5 6 7 8 9 10
Tem
péra
ture
(°C
)
Temps (min)
Essai R1 - Section N010
TE_N010_5 TE_N010_4 TE_N010_3 TE_N010_2 TE_N010_1
TE_N010_5 FDS TE_N010_4 FDS TE_N010_3 FDS TE_N010_2 FDS TE_N010_1 FDS
0
50
100
150
200
250
300
350
400
0 1 2 3 4 5 6 7 8 9 10
Tem
péra
ture
(°C
)
Temps (min)
Essai BEHP1B - Section S050
TE_S050_5 TE_S050_4 TE_S050_3 TE_S050_2 TE_S050_1
TE_S050_5 FDS TE_S050_4 FDS TE_S050_3 FDS TE_S050_2 FDS TE_S050_1 FDS
Good agreement ⇒ possible use of FDS tosimulate fire scenarios in the tunnel.
4. RESULTSDesign heat release rate curvesSimplified HRR curves derived from TST tests and from scientific litterature [4] :
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15Time (min)
10
20
30
40
50
60
70
80
90
100
0
15 MW
6 MW10 MW
HR
R (
MW
)
15 MW
Early activation
Delayed activation
No activation
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
10
20
30
40
50
60
70
80
90
100
0
30 MW
6 MW
15 MW
Time (min)
HR
R (
MW
)
30 MW
Early activation
Delayed activation
No activation
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
10
20
30
40
50
60
70
80
90
100
0
50 MW
10 MW
20 MW
Time (min)
HR
R (
MW
)
50 MW
Early activation
Delayed activation
No activation
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
10
20
30
40
50
60
70
80
90
100
0
100 MW
30 MW
50 MW
HR
R (
MW
)
Time (min)
100 MW
Early activation
Delayed activation
No activation
Numerical results analysisFDS results postprocessing to analyse water mist effect and to identify evacuation con-
ditions along the tunnelIntensive use of REVAC in-house numerical model for simulating evacuation and firefight-
ers intervention (including traveling speed reduction and fractional effective dose for usersincapacitation derived from [5])
Walking speed vs visibility distance Estimated visibility distance through water mist
5. CONCLUSION36 realistic fire scenarios (4 fire loads, 3
natural draught conditions, 3 FFS activation)Significant degradation of visibility and
temperature in the flooding areaNo real asset for safety of users because
the smoke management system is effectiveGood results to protect structure and
equipment when facing big fires
6. REFERENCESSETEC TPI-CSTB :Campagne de tests de sfli par le GEIE TMB, 2013.Ref. 003-23776/6/T/145/JMV-TU-FR-20121114-v2.IFAB :Campagne de tests des systemes fixes des lutte contre l’incendie pour le tunnel duMont-Blanc, dossier de presentation du tunnel d’essai, 2011.
NIST Special Publication 1019.Fire Dynamics Simulator User’s Guide, 2017.
SOLIT :Safety of life in tunnels, water mist fire suppression for road tunnels, final report,2007.SFPE :SFPE Handbook of Fire Protection Engineering, Third edition.National Fire Protection Association, Quincy, 2002.