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Mina_Shahi June 22, 2011 10:11

Combustion in a Back ward facing step
 
2 Attachment(s)
Dear All

I am trying to model combustion in a back ward facing step for propane air mixture and then compare the result by Robert W Pitz and John W.Daily but the flame shap is really depended on initial condition. First i am doing steady state simulation for Propane Air WD1.
First i had problem because the mixture didn't ignite, then i divided the domain to two region and set higher temperature in ignition domain close to the step.
but still the flame shap is different with that of the paper.
Can some one please help me?

Mass fraction of C3H8 = 0.077
Mass fraction of O2=0.4912

Attachment 8145

Attachment 8146

Mina_Shahi June 27, 2011 05:52

Source point in combustion modeling
 
Dear All

Does any body know about source point? actually i am looking for other way to ignite my mixture because i think ignition zone or using two regins is not good way. i am trying to use source point but i don't know how. can you please some body help me.

maesims July 10, 2011 19:57

try auto-ignition option
 
Hi,
Are you using the eddy dissipation model? Try using auto ignition and you should be able to get the mixture ignited.
The other way of doing it is you can initialize the domain and use a very small value for CO2.mf or H2O.mf = 0.00001 and then run your sim.
You should not require multiple domains to ignite.

Thanks.

Mina_Shahi July 19, 2011 05:36

Hi

Many Thanks.
Indeed i am using eddy dissipation and also Finite rate chemistry model and BVM.
You mean first i should put both fresh mixture and burnt mixture as an initial value (CO2.mf or H2O.mf = 0.00001 )?
i need multiple domains because when i set higher temperature in the whole domain it will be diverged , so i set two domains one which i call ignition zone has higher temperature. but this is not also a good way because in this way the flame will be confined in this domain.

I will appreciate if you can give me advice

Mina_Shahi July 19, 2011 05:37

Re: auto-ignition option
 
Hi

Many Thanks.
Indeed i am using eddy dissipation and also Finite rate chemistry model and BVM.
You mean first i should put both fresh mixture and burnt mixture as an initial value (CO2.mf or H2O.mf = 0.00001 )?
i need multiple domains because when i set higher temperature in the whole domain it will be diverged , so i set two domains one which i call ignition zone has higher temperature. but this is not also a good way because in this way the flame will be confined in this domain.

I will appreciate if you can give me advice


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