uses of fire dynamics simulator v4
DESCRIPTION
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Uses of Fire Dynamics Simulator V4 Uses of Fire Dynamics Simulator V4 for Large Scale/Industrial Incidentsfor Large Scale/Industrial Incidents
HUGHES ASSOCIATES, INCFIRE SCIENCE & ENGINEERING
Jason E. FloydJason E. Floyd
2004 Loss Prevention Symposium2004 Loss Prevention SymposiumAIChEAIChE 2004 Spring Meeting2004 Spring Meeting
New Orleans, LANew Orleans, LAApril 25 April 25 –– April 29, 2004April 29, 2004
Fire Dynamics Simulator (FDS)Fire Dynamics Simulator (FDS)Developed by NIST Building and Fire Developed by NIST Building and Fire Research LaboratoryResearch LaboratoryCompanion software called Companion software called SmokeviewSmokeview for for viewing/animating FDS outputviewing/animating FDS outputLarge eddy simulation (LES)Large eddy simulation (LES)Single parameter mixture fractionSingle parameter mixture fractionGray gas, finite volume radiation heat transferGray gas, finite volume radiation heat transfer1D temperature dependent heat conduction 1D temperature dependent heat conduction through surfacesthrough surfaces
Additional FDS CapabilitiesAdditional FDS CapabilitiesMultiMulti--block grids (single processor or MPI)block grids (single processor or MPI)Ignition of remote objectsIgnition of remote objectsPool fires with calculated heat release ratesPool fires with calculated heat release rates**Fire spread and growth over solid fuels Fire spread and growth over solid fuels (charring and thermoplastic)(charring and thermoplastic)**DropletsDroplets* * -- fuel spray fires, sprinklers fuel spray fires, sprinklers (convention and mist)(convention and mist)Fire suppression by oxygen depletion and Fire suppression by oxygen depletion and fuel cooling or delivered waterfuel cooling or delivered water**
**Level of physical detail in Level of physical detail in submodelssubmodels may not support its use for all applicationsmay not support its use for all applications
AcknowledgementsAcknowledgementsKevin Kevin McGrattanMcGrattan (NIST) (NIST) –– Lead software developerLead software developerGlenn Forney (NIST) Glenn Forney (NIST) –– SmokeviewSmokeview developerdeveloperHoward Baum (NIST) Howard Baum (NIST) –– Radiation and combustion Radiation and combustion theorytheoryRonald Ronald RehmRehm (NIST) (NIST) –– Large outdoor fires, windLarge outdoor fires, windDave Sheppard (ATF) Dave Sheppard (ATF) –– SprinkerSprinker spray spray measurementsmeasurementsUri Uri Vandsburger(VTVandsburger(VT), Chris ), Chris WieczorekWieczorek (FM)(FM)––UnderventilatedUnderventilated fires, validation datafires, validation dataSimoSimo HostikkaHostikka (VTT) (VTT) –– Radiation heat transferRadiation heat transferMarino Marino didi MarzoMarzo (UMD) (UMD) –– Droplet heat transferDroplet heat transfer
Fire vs. Combustion Fire vs. Combustion SimulationSimulation
Combustion simulation Combustion simulation –– Numerical modeling Numerical modeling of the physical and chemical processes of the physical and chemical processes related to combustion at highly resolved related to combustion at highly resolved temporal and spatial scales.temporal and spatial scales.Fire simulation Fire simulation –– Large scale numerical Large scale numerical modeling of combustion and transport modeling of combustion and transport processes at the dominant hydrodynamic processes at the dominant hydrodynamic length and time scales.length and time scales.
Guiding Development Guiding Development PrinciplesPrinciples
Target user is the practicing FPE/AHJTarget user is the practicing FPE/AHJCode must be Code must be ““easyeasy”” to useto use
•• Creation of input filesCreation of input files•• Usability of output filesUsability of output files
Code must be low cost (hardware+software)Code must be low cost (hardware+software)Code must be fastCode must be fast
Keep Keep submodelssubmodels of similar relative accuracyof similar relative accuracy
HydrodynamicsHydrodynamicsConservation of MassConservation of Mass
Conservation of SpeciesConservation of Species
Conservation of MomentumConservation of Momentum
Divergence (Conservation of Energy)Divergence (Conservation of Energy)
uut
rr⋅∇−=∇⋅+
∂∂ ρρρ
iiiii WYDuYYu
tY ′′′+∇⋅∇+⋅∇−=∇⋅+
∂∂ &rr ρρρρ
( )( )τρρρ
ϖ ⋅∇++−=∇+×+∂∂
∞ fgutu rrvrrr 1H
⎟⎟⎠
⎞⎜⎜⎝
⎛−
−∇⋅∇+∇⋅∇+⋅∇−′′′−
=⋅∇ ∑ dtdpYDTcTkqq
pu
iiipr
0,
0 111
γρ
γγ
&r
HydrodynamicsHydrodynamicsPressure TermPressure Term
Viscosity Term
~2 121 pu ∇+∇=∇
ρrv
H
Viscosity Term
( ) ( ) ( ) ( )22
322 uudefudefCsLES
rrr⋅∇−⋅∆= ρµ
DiscretizationDiscretizationSimple Cartesian or cylindrical, Simple Cartesian or cylindrical, multiblockmultiblock grid (No body fitting)grid (No body fitting)Scalar quantities (temperature, density, Scalar quantities (temperature, density, etc.) defined at cell centersetc.) defined at cell centersVector quantities (velocity) defined at Vector quantities (velocity) defined at cell edgescell edgesDifferences 2Differences 2ndnd order in spaceorder in space
SubmodelsSubmodels
Mixture Fraction CombustionMixture Fraction CombustionFinite Volume RadiationFinite Volume RadiationSolid phaseSolid phaseLiquid phaseLiquid phase
Mixture Fraction DefinitionMixture Fraction Definition
Conserved scalar quantity: ZConserved scalar quantity: Z
Z = 0 = ambient air, Z = 1 = pure fuelZ = 0 = ambient air, Z = 1 = pure fuelIf YIf YF F and Yand YO O = 0, then Z = Z= 0, then Z = ZFF = flame = flame sheetsheet
OO
O
FF
OO
OO
FF
F
MY
M
MYY
MY
Z
υυ
υυ∞
∞
−
−−
=1
ImplementationImplementationCombine the equations for Combine the equations for conservation of oxygen and mixture conservation of oxygen and mixture fractionfraction
Apply Apply HuggetHugget’’ss relationship.relationship.
( )FZZ
OO nZD
dZdY
m=
⋅∇=′′− ˆ2
2ρ&
( )FZZ
OOO nZD
dZdY
Hq=
⋅∇∆−=′′′ ˆ2
22ρ&
State RelationshipState RelationshipStart with generic combustion equation Start with generic combustion equation for a fuelfor a fuel
Modify to allow for nonModify to allow for non--stoichiometricstoichiometricstatestate
222222222
22
22
22
22 NMYMY
OHCONMYMY
OFNO
ONOOHCO
NO
ONOF ∞
∞
∞
∞
++⎯→⎯⎟⎟⎠
⎞⎜⎜⎝
⎛++ υυυυυ
[ ]
[ ] [ ] 2222
22222
22
22
22
2
2
22
22
,1,1
2,01,0
NMYMY
xOHxMinCOxMin
OxMaxFxMaxNMYMY
OxF
NO
ONOOHCO
OHCOOF
NO
ONOF
∞
∞
∞
∞
×++
⎥⎦
⎤⎢⎣
⎡−−×+−⎯→⎯⎟
⎟⎠
⎞⎜⎜⎝
⎛+×+
υυυ
υυυυυυ
State RelationshipState RelationshipCombustion Takes Place At ZCombustion Takes Place At ZFF
For Coarse Grids, ZFor Coarse Grids, ZFF Surface Will Not Be ResolvedSurface Will Not Be Resolved
0.00.10.20.30.40.50.60.70.80.91.0
0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0
Mixture Fraction (Z)
Mas
s Fr
actio
n
Methane Oxygen NitrogenCarbon Dioxide Water Vapor
ZF
Mixture Fraction SurfaceMixture Fraction SurfaceVirginia Tech Fire Compartment FDS v2 Simulation
400 kW propane fire in a 50%-scaled ISO-9705 Compartment
Radiation Heat TransferRadiation Heat Transfer
Start with gray gas radiation transport Start with gray gas radiation transport equationequation
Divide path vector over a number of Divide path vector over a number of discrete angles and apply to each grid discrete angles and apply to each grid cellcell
( ) ( ) ( ) ( )[ ]s,xIs,xIxs,xIs brrrr
−=∇⋅ κ
( ) Lijk
Lijkijk,bijkm
m
Lmm dVIIdnsIA
L
Ω−=Ω⋅∫∑Ω=
κ6
1
Radiation Heat TransferRadiation Heat Transfer
κκijkijk is is precalculatedprecalculated as a function of as a function of temperature and mixture fraction using temperature and mixture fraction using RADCAL.RADCAL.
The radiant source term, The radiant source term, IIb,ijkb,ijk, for a grid , for a grid cell is the larger of cell is the larger of σσTT44 or the radiant or the radiant fraction of the cells heat release.fraction of the cells heat release.
MultiblockMultiblock GridsGridsMultiple computational gridsMultiple computational gridsCan have different node sizesCan have different node sizesReduction of active grid cells at the expense Reduction of active grid cells at the expense of more complex boundary conditionsof more complex boundary conditions
DropletsDroplets
LaGrangianLaGrangian superdropsuperdrop..RosinRosin--RammlerRammler size distribution for spray size distribution for spray nozzles with user defined angular dependent nozzles with user defined angular dependent spray pattern (velocity and mass flux)spray pattern (velocity and mass flux)Evaporation governed by droplet heat Evaporation governed by droplet heat transfer and local equilibrium vapor mass transfer and local equilibrium vapor mass fraction (fraction (ClausiusClausius--ClapeyronClapeyron ))Droplet absorption scattering added to Droplet absorption scattering added to radiation transport equationradiation transport equation
Droplets + RadiationDroplets + RadiationRight Wall Hot, Cold SprayRight Wall Hot, Cold Spray
ExamplesExamples
Sprinkler effectivenessSprinkler effectivenessLarge outdoor fireLarge outdoor fireImpinging spray fireImpinging spray fire
Sprinkler ActivationSprinkler Activation((McGrattanMcGrattan and Stroup, 1997)and Stroup, 1997)
6767’’11””
SprinklersSprinklersw/10w/10’’ Spacing
Draft CurtainDraft CurtainSpacing
44’’x8x8’’ Roof VentRoof Vent
7171’’22””
FDS v1Test
Time to ActivateTime to Activate 1:091:28
1:111:12
2:362:52
2:343:58
DNO6:52
2:112:06
2:163:30
1:111:28
1:121:20
2:222:38
2:264:20
2:455:48
2:442:40
~4.5 MW Heptane~4.5 MW HeptaneSpray FireSpray Fire
Sprinkler EffectivenessSprinkler Effectiveness
Sprinkler
Fire Origin
Sprinkler
Fire Origin
Time (s)
Hea
tRel
ease
Rat
e(k
W)
Link
Tem
pera
ture
(°C
)
0 100 200 300 400 500 6000
200
400
600
800
1000
1200
1400
1600
0
20
40
60
80
HRR w/o SprinklersHRR w/ SprinklersLink Temp FirstLink Temp Second
Sprinkler EffectivenessSprinkler Effectiveness
Tank FarmTank Farm
Tank Farm Fire w/ and w/o Tank Farm Fire w/ and w/o WindWind
Heptane Spray FireHeptane Spray Fire
Impinging Spray FireImpinging Spray Fire