CFD Modeling of Large Scale Fires based on OpenFOAMpowerlab.fsb.hr/ped/kturbo/OpenFOAM/SummerSchool2010/Yi.pdf · CFD Modeling of Large Scale Fires based on OpenFOAM Yi Wang FM Global,

CFD Modeling of Large Scale Fires based on OpenFOAM

Yi WangFM Global, Research DivisionNorwood, MA, USA

OpenFOAM Summer School, Sep 1st - Sep 15th, 2010, Zagreb, Croatia

Fire growth and suppression

Buoyancy-driven wall-bounded turbulent flow

Diffusion combustion & soot formation

Radiative & convective heat transfer

Pyrolysis

Droplet atomization

Droplet transport

Pre-wetting

Surface suppression

Fire growth Fire suppression

FireFoam solver• Buoyancy driven reacting flow

– Density – velocity coupling– Choice of equations

• Total enthalpy and mixture fraction– HRR calculation?– Multiple streams? – Conservation of enthalpy?

• Sensible enthalpy and species– Efficiency and stability

• Coupling with other physical models

Energy conservation• 1 vs 3 outer loops• Better when use sensible enthalpy equation

Buoyancy driven flow• Density – velocity coupling

– grad(p) + rho*g– P = p0 + pd + rho * gh– grad(pd) + gh*grad(rho)– fvc:reconstruct()

Stability and efficiency• Co number: increase form 0.5 to 5

– Under-relaxation (0.9) • U, Yi, hs

– Euler of Yi, Hs– Backward for U

Topological change• Proof of concept for box burn-though

• Step one– Add stitchPatch functionality into top solver

• Step two – attachDetachFvMesh: topoChangerFvMesh– FireDyMFoam (with pyrolysis)

• Stability issues

Animation

CFD Modeling of Large Scale Fires based on OpenFOAMFire growth and suppressionFireFoam solverEnergy conservationBuoyancy driven flowStability and efficiencyTopological changeAnimation