[Hagen]

Originally Posted by Uyan

Hagen,

Here you have said the mixture fraction is calculated using a small amount of Argon added from the fuel inlet.

I just wanted to know if my understanding is correct.

Is it added as a tracer element so within the counter-flow flame thickness instead of calculating mixture fraction explicitly by Bilger's formulation, Yar/Yar_fuel is used as the mixture fraction ?

Dear Uyan,

that's correct, Yar/Yar_fuel is used. The code is in line 585 of Cantera-CounterflowFlame/src/flamelet.cpp.

Best wishes, Hagen

[Uyan]

Thank you Hagen and Wenxu,

So user must always specify a very small amount of Argon at the Fuel inlet right?

But, flamelet script seems to work without initial solution with no Argon.How can that happen?

In the paper suggested by Wenxu, by Prof Pitsch and Prof Peters discuss about a third method for mixture fraction which is different from more popular two feed system and Bilger's formula. They define mixture fraction conserved scalar transport equation. [Eqn 13]

That method is quite similar to Argon transport equation, so I guess that is the theory behind using Argon ?

[faeze.d]

Originally Posted by babakflame

Dear Likun

My suggestion is first check the LES properties file in O.F. 2.3.o to see whether other inputs are needed in your LES properties file or not (for smagorinsky model).

nest step, might be check the code for adding headers that might be needed.

Best,
Bobi

Hi Bobi
i am using flameletfoam to simulate a DLR-A flame. as you may know it's a free flame and i have some troules with boundary conditions. the B.Cs are:
Uinlet : fixedValue
Uoutlet: inletoutlet
Uoutside: pressureinletoutletvelocity

T is calculated for all boundaries
P is totalpressure at the outside and outlet and zerogradient at the inlet bounderies.

but there is reflections in the outside boundaries. do you have any suggestion?
thank you

[babakflame]

Hey Faeze

I am not working on combustion any more. However, for hinting you I should say:

The reflections from outside boundary might happen more frequently in future when you want to simulate swirl flames

Let me know are you using LES or RAS , give me a little perspective of your grid as well.

I will put a general post so as to be useful for everybody and avoid multiple questions

[conga8893]

Hi everyone,

First, Hagen, I have to thank you very much for developing the new useful solver that help me a lot and this thread also is very interesting.

Now, I'm confused some places in the Z boundary conditions of the case flame Sandia D in tutorial. In fact, the boundary condition of Z for patch PILOT is 0.271. How can you calculate this value? and can you explain it mathematically?
PILOT
{
type fixedValue;
value uniform 0.271;
}

Have a good day,
Minh

[Adlak]

Originally Posted by Likun

Hi Howard,

I fully agree with what Hagen said. Flamelet model by concept is for modeling of non-premixed combustion. For premixed combustion you need progress variable as the independent variable instead of mixture fraction as in flamelet model. However, for partially-premixed flame you still need mixture fraction. I think the best way for you is to modify this code, add progress variable. This should not be too difficult if you understand the structure of flameletFoam. I have already implemented FGM model based on the flameletFoam, and it is working fine. After adding progress variable, you need generate a lookup table using progress variable (and mixture fraction) as independent variable. This can be done by Cantera, FlameMaster or CHEM1D. I am using CHEM1D flame Eindhoven university.

Good Luck!

Best,
Likun

Hi Likun,

I want to generate flamelets for h2-air non-premixed combustion. Can u help me how to do that using chem1d.

Thanks