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