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Old   January 17, 2011, 13:04
Default simulating comb with reactingFoam
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Josť Rodrigues
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Hi,

Im trying to simulate combustion inside a CAN Type Gas Turbine Combustion Chamber with methane (CH4).

In case you know, the input conditions and the mesh are similar to the 3-step EDU tutorial from the straccm+ manual. If thats not the case, shortly, the setup consists of a 60 degree wedge with 2 swirling air inlets to the main chamber, 1 swirling fuel(CH4) inlet and one 3rd air inlet running in an outer channel for cooling. Both the 2 air inlets and the fuel inlet are characterized with cylindricalInletVelocity BC, supplied with OF-1.7.1.

MESH
The Can is 1m long and .25m radius and the domain only represents a 60 degree wedge section of the Can. The mesh as 1800 cells (coarse mesh). The wedge sides have symmetryPlane BC.


I tried to run this simulation with reactingFoam solver modified to account ignition (as purposed in the OFwiki).
Plus, most of the settings of the several dicts were taken from the counterFlowFlame2D tutorial (such as initialChemicalTimeStep and other coeff). RANS was used for turbulence modeling.


RESULTS
At 1st, I used the ode chemistrySolver in the chemistryProperties dict but i got the janaf out of range error. The temp exceeded the 5000k limit.

Next, I used the sequential chemistySolver and then I got a solution. However, the residuals were very unstable with a courant no. of 0.5 and the MAXtemp would oscillate between 2600k and 3100k.

QUESTIONS:
1. What are the basis of either the sequential and the ode chemistrySolvers? Can you give some references to this models?

2. Which Courant number should I set?

3. Can I use different ddt schemes such as CrankNicholson with reactingFoam? What about steadyState?

4. Which settings would you recommend to tune so I can achieve convergence. I m avoiding refining the mesh to keep the setup as close as possible to the tut in starccm+.

5. Is it possible to use dieselFoam without injectors or spray?

That is all =P
I sincerely hope this thread will be a contribution to the OFOAM community!
Thank you.
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Old   January 20, 2011, 05:47
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Nakul
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Hi,

This JANAF error is quite a common problem with reactingFoam. It occurs mainly due to wrong case setup and there could be many reasons for setup to go wrong,

As for your questions:

1) Its advisable that you check out the source code in "src/thermophysical/chemistry" to find out the details of these chemistry solvers. If however you come across some reference do post it here. I would also be interested in goin through them.

2) Based on my experience I have found that for reactingFoam, max Co=0.1 is best suited.

3) There could be some stability issues if you change the ddt scheme. But you can give it a try. Also for steady state a separate solver called steadyReactingFoam is available.

4) You may do a "checkMesh" to see if everything is alright with your mesh. If not then you would have to change it. Apart from this to achieve convergence have a look at your BC and IC. They are the primary source of "JANAF" error.

5) Yes I think there shouldn't be any problem in doing that. Its code is exactly similar to that of reactingFoam. You may give it a try too.
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Old   February 7, 2011, 12:16
Post Ignition method
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Tang
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Hi Josť,

I'm also trying to simulate a one step methane combustion inside a cylindrical burner with reactingFoam and I'd like to modify this solver to account for ignition. I modified it as mentioned on the OFwiki and run the case it runs without error but not ignition occurs. Apparently the combustionProperties file is not read at all since when I start the run it get the following message, and (correct me if I'm wrong) it should be read together with "chemistryProperties" "g" and "thermophysicalProperties":

/************************************************** ************************************************** ***************/
Create time

Create mesh for time = 0

Reading chemistry properties


Reading g

Reading thermophysicalProperties
Selecting psiChemistryModel ODEChemistryModel<gasThermoPhysics>
Selecting thermodynamics package hsPsiMixtureThermo<reactingMixture<gasThermoPhysic s>>
Selecting chemistryReader foamChemistryReader
Selecting chemistrySolver ode
Selecting ODE solver SIBS
ODEChemistryModel: Number of species = 5 and reactions = 1
Reading field U

Reading/calculating face flux field phi

Creating turbulence model.
/************************************************** ************************************************** ***************/
Did you encounter the same problem? Is the procedure also valid for OF-1.7.7? You should know that I'm quite unfamiliar with the use of OF and C++.

Thanks a lot for any kind of help
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Old   February 7, 2011, 12:36
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Josť Rodrigues
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Hi Tang,

You re right: your solver is not reading the combustionProperties files. The beguining of the solver output should be something like:


Create time

Create mesh for time = 0

Reading chemistry properties

Reading combustion properties

Found ignition cells:
1(934)


Ignition on

Reading g

...

I recommend that you recheck all the steps from the OFwiki tutorial. Make sure you use a different name for the solver like reactingFoamIgnition (as i did).

Cheers
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Old   April 6, 2012, 16:31
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Mostafa Moghaddami
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Dear All

I am going to run a case includes some liquid species that react with each other. I am going to use the reactingFoam as a solver.
All species have constant proprties and I want to use the following thermo type:
thermoType hsPsiThermo<reactingMixture<constTransport<specieT hermo<eConstThermo<icoPolynomial>>>>>>

but when I set it in the constat/thermophysicalProperties file and run the case, I get this error:

------------------------------------------------------------------------------------
--> FOAM FATAL ERROR:
Inconsistent thermo package selected:

hsPsiThermo<reactingMixture<constTransport<specieT hermo<eConstThermo<icoPolynomial>>>>>>

Please select a thermo package based on gasThermoPhysics. Valid options include:

3
(
hsPsiMixtureThermo<singleStepReactingMixture<gasTh ermoPhysics>>
hsPsiMixtureThermo<multiComponentMixture<gasThermo Physics>>
hsPsiMixtureThermo<reactingMixture<gasThermoPhysic s>>
)



From function autoPtr<hsCombustionThermo> hsCombustionThermo::NewType(const fvMesh&, const word&)
in file combustionThermo/hsCombustionThermo/hsCombustionThermoNew.C at line 116.

FOAM exiting
-------------------------------------------------------------------------------------

What should I do to use the reactingFoam for constant propertie species?

Thanks in advance for your help.
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