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Old   September 30, 2016, 05:49
Default Need help for partially premixed combustion model?
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Hi all,

I am simulating biomass-producer gas combustion in a cylindrical chamber has single inlet/outlet.

Diameter of chamber is 250 mm/length 500 mm.
diameter of inlet/outlet are 50 mm.
Meshed with tetrahedral for whole of domain and inflation for chamber wall.
Achieved 203061 elements, skewness Max 0.764, and orthogonal quality 0.999.

Energy, Standard k-e, Standard wall Fn, P1 and Partially Premixed-combustion Model.

PDF table creation:
Chemical equilibrium, Non-adiabatic with fuel stream rich flammability 0.6

Boundary tab: mole fraction of producer gas is (0.14 h2, 0.456 n2, 0.017 o2, 0.24 co, and 0.147 co2) with 470k temperature for both fuel/oxidizer.

Materials: selected absorption coefficient as wsggm-domain-based and cement properties for the wall.

Inlet: mass flow rate 0.04 kg/s, turbulent intensity 10%, hydraulic diameter 0.05m, 470 for temperatures, and mean mixture fraction, 0.529 (based on stoichiometry air-producer gas mixture).
Outlet: pressure outlet, turbulent in 10%, hydraulic diameter 0.05m, backflow progress 1, and backflow Temperature 1000k.
Wall: heatflux 4800, internal emissivity 0.7, wall thickness 0.1m.

Solution Methods: SIMPLE and First Order Upwind (in the first solution).
Solution procedure:
1) selected equations for solving included Flow, Turbulence, Energy and P1
initialization with all zones, enter 1 for progress variable.
2) adapt region on inlet zone and patch with 0 for progress variable and solve for all equation (by flowing the tutorial of Partially Premixed combustion).

After some iterations, I checked the results it seems like no reaction inside chamber.
My understanding, the mole fraction of CO should be as an initial value in bottom (or near inlet zone) and slowly decreased next till into the top of chamber (or near outlet zone).
But in my solution seems like achieving constant value of CO inside the chamber.
Even I patched in high temperature (2000k) and tried with different methods, but got the same results.

I dont know what is wrong with my solution... can anyone help to fix this?

Thank you!

see the results

Last edited by lem; October 1, 2016 at 23:29.
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