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IDProjectCategoryView StatusLast Update
0000453OpenFOAMBugpublic2012-04-02 17:38
Reporteruser305Assigned Touser21 
PriorityhighSeveritymajorReproducibilityalways
Status closedResolutionfixed 
PlatformLinuxOSUbuntuOS Version10.04
Summary0000453: reactingFoam - to high temperature and wrong gas mixture depending on kinetics
DescriptionAs it is reproduced in the attached case the temperature of a premixed methane-air flame reaches nearly 5000 K. The real adiabatic temperature should be about 2200 K. CO2 and H2O are calculated to high (about 40 and 25 m-%) and N2 to low. A stoichiometric combustion of methane should produce about 15% CO2, 12% H2O and 73% N2. This effect depends on the arrhenius reaction coefficients. If you choose a lower value of A=5.2e14 instead of A=5.2e16 (in /constant/reactions) the calculated output is correct.
Steps To ReproduceI'll attach a case
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user305

2012-03-08 14:33

 

ReactingFoam.tar.gz (139,056 bytes)

user21

2012-03-13 15:39

  ~0001136

I agree regarding the adiabatic temperature and the ratio of the product of combustions. I don't think the problem lies on the factor of the Arrhenius reaction (A) but in the combustion model parameters for your case. Your mesh resolution is (8.3e0-3 m) which is larger than the reaction zone (~1 mm). Thus,

In our tutorial for reactingFoam the temperature is about right 2200 K, but we use a grid resolution of 2e-4 m. You'd need to adjust Cmix to account for the proper mixing/burning of your combustion. Probably reading some bibliography for a PaSR modelling would help.

Regards

Issue History

Date Modified Username Field Change
2012-03-08 14:33 user305 New Issue
2012-03-08 14:33 user305 File Added: ReactingFoam.tar.gz
2012-03-13 15:39 user21 Note Added: 0001136
2012-03-13 15:39 user21 Assigned To => user21
2012-03-13 15:39 user21 Status new => assigned
2012-04-02 17:38 user21 Status assigned => closed
2012-04-02 17:38 user21 Resolution open => fixed