[remir]

Hello to you, dear Foamers.


I am currently experiencing troubles when trying to use reactingFoam to simulate with LES the Pitz and Daily case with premixed air-propane . It is indeed impossible to start or maintain the combustion using an irreversibleArrheniusReaction reaction. ( No product is ever being created !)
I use the following mechanism (Westbrook’s mechanism (1981) ):

reactions
{
Reaction
{
type irreversibleArrheniusReaction;
reaction "C3H8^0.1 + 5O2^1.65 = 3CO2 + 4H2O";
A 8.6e11;
beta 0;
Ta 15000;
}
}

Everything works fine when I use a methane reaction, with one global step or 4 steps. I tried to simulate my case with methane combustion instead of propane, and after the combustion is well established, I just changed the switched to propane (renaming CH4 into C3H80 and changing the reaction), but the hot products just got convected away and no new products were created. I tried to replace the thermodynamics data of C3H8 by the CH4's in order to see if that could be the problem, but nothing changed.I also tried to increase A a lot, or reduce Ta, without any success. ( I thought the units might have been the issue)

I am starting to think that I forgot something ( maybe obvious?)
I would like to know what reduced mechanism I should used for propane combustion ( less than 10 steps would be great), in chemkin or openfoam format.
For example in http://www.cfd-online.com/Forums/ope...mechanism.html , Robert gives the following mechanism :
C3H8 + 1.5O2 -> 3CO + 4H2
CO + 0.5O2 -> CO2
H2 + 0.5O2 -> H2O

but I don't know how to find the related coefficients (A,b,Ta).

The inlet Bcs for my case are:
U=13.3m/s
C3H8=0.024
O2=0.20496
N2=0.77104

I am currently using OF2.2.2.

I don't know if my problem comes from the mechanism, the mixture equivalence ratio, a file I forgot to change ...

Any idea on how to make it work?

[dimaCFD]

hi,

you can try a three-step mechanism from this paper:
V. Sabelnikov, Ch. Fureby, LES combustion modeling for high Re flames using a multi-phase analogy, Combustion and Flame 160 (2013) 83–96

It works fine for me.

Thx, Dmitry
http://www.edcpisofoam.decgroup.org/

[remir]

Thanks a lot for your answer Dmitry.
I will try the mechanism asap

Remi

[fabri]

Hi remir I have the same problem with my testcase.
when I write the reaction with exponent like this:

CH4^-0.3 + 2O2^1.3 = CO2 + 2H2O

Did you solve your problem?
Thank you very much

Fabri