Thanks Dave,

I think I can work with the timeVaryingFixedValue bc.

I changed the ODESolver from SIBS to KRR4 and the flame temperature increased.

there is one think I don't understand. i am running my case without a combustionProperties fine in the /constant folder. seems like this file arrange the ignition:

/*---------------------------------------------------------------------------*\
| ========= | |
| \\ / F ield | OpenFOAM: The Open Source CFD Toolbox |
| \\ / O peration | Version: 1.0 |
| \\ / A nd | Web: http://www.openfoam.org |
| \\/ M anipulation | |
\*---------------------------------------------------------------------------*/

version 1.0;
format ascii;
root "";
case "example";
instance "constant";
local "";
class dictionary;
form dictionary;
object combustionProperties;

// ************************************************** *********************** //

Cmix Cmix [ 0 0 0 0 0 0 0 ] 1.0 ;

ignitionProperties1
{
ignite on;

ignitionPoint ignitionPoint [ 0 1 0 0 0 0 0 ] ( 0.01 0 0 ) ;

timing timing [ 0 0 1 0 0 0 0 ] 0.0e-1 ;

duration duration [ 0 0 1 0 0 0 0 ] 1.0e-0 ;
}

// ************************************************** *********************** //

So I just copied this file from the reactingFoam tutorial and put it in my \constant folder of my case. but I have the feeling that reactingFoam solver doesn't read this file and solve my case like before without this file. do you know how to integrate this file to my case?

and in general: seems like there are a couple op necessary *properties-files line chemestryProperties. if i want to add some additional files like in my case combustionProperties, do i have to declare them, or do the sover read theam automaticlly?

big thanks for your help Dave!!!

regards,

ilja

Ilja,

You will need re-compile with modifications to the reactingFoam source code for an "igniter". If you are using 1.6.x, coalChemistryFoam provides an example of how to do this. You will need modify createFields.H and hEqn.H (which is borrowed from XiFoam). The syntax for the ignition is in the coalChemistry tutorial "constant" directory "enthalpySourceProperties". You could also run coalChemistryFoam and disable the particles and radiation.

Dave

It is a silly quastion, but where i can find these files "createFields.H" and "hEqn.H", i mean in which diractionary? is it the diractionary "/OpenFOAM-1.6/applications/solvers/combustion/reactingFoam"? as you see, i am not very familiar with OF. how could i create a new solver (or modify a existing one)? with which code (and from which files) is OF running a case, if i am typing "reactingFoam" into the terminal?

Regards,

Ilja

Hey Dave,

thanks again for your help. i allready managed to set up an igniter.

there is one think i would like to know. how to reach the steady state? i not really interested in the time variating distribution, but at the time where the temperature is fixed.

is it possible to modify the reactingFoam solver to bring the simulation to the point of a steady state?

best regards,

Ilja

Access to SpecieThermo data
 

Dear All,

Does any of you know to access to the thermodynamic propertie of species such as hi(T) where hi is enthalpy of ith specie and Ti is temprature of cell?
In openFoam-1.5 you can write

hi = chemistry.specieThermo()[i].h(Ti); and it works. See disealengienfoam solver in openfoam-1.5.

However, in OpenFoam-1.6 if you write the same you get psichemistrymodel has no memebr specieThermo.

How can we use specieThermo in OpenFoam-1.6?

I have the same problem. Did you fixed it? I want to access specieThermo.Hc().

hi, me too... do u figure it out?:)

Unfourtunatly, I am still looking..... :mad:

doh!:o Let me know if u fix it.... I'll do the same

sure, I will do

Turbulent reaction info
 

Hey Guys,

Please through some light on the following questions:

1. For coalChemistryFoam during the setup of chemistryProperties file, there is a switch for turbulentReaction on/off; I am wondering how and which files account for turbulence on the reaction rates. can you please send the link of the files. I am using OpenFoam-1.6

2. What are available combustion models in OpenFoam. Are there tutorails for simulating a sample case with different combustion models?

Many thanks in advance.
NirA

Hi NirA,

There are many combustion models in OpenFOAM. You can run the available tutorials in OpenFOAM.

For Q1, I cannot understand what do you mean?

Hi Hassan,

What I meant was in the sub-directory constant/, there is afile chemistryProperties. In the chemsitryProperties, we specify for example that we can use ODEchemistry whichl will use ODE solver. There is also an option of using turbulentReaction.

So I am trying to figure out which library and which files in the solvers or source code modifies the reaction rate due to turbulence?

My chemistryProperties looks as follow:

/*--------------------------------*- C++ -*----------------------------------*\
| ========= | |
| \\ / F ield | OpenFOAM: The Open Source CFD Toolbox |
| \\ / O peration | Version: 1.6 |
| \\ / A nd | Web: www.OpenFOAM.org |
| \\/ M anipulation | |
\*---------------------------------------------------------------------------*/
FoamFile
{
version 2.0;
format ascii;
class dictionary;
location "constant";
object chemistryProperties;
}
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
psiChemistryModel ODEChemistryModel<gasThermoPhysics>;
chemistry on;
turbulentReaction on;
chemistrySolver ode;
initialChemicalTimeStep 1e-07;
sequentialCoeffs
{
cTauChem 0.001;
equilibriumRateLimiter off;
}
EulerImplicitCoeffs
{
cTauChem 0.05;
equilibriumRateLimiter off;
}
odeCoeffs
{
ODESolver SIBS;
eps 0.05;
scale 1;
}
//Cmix Cmix [ 0 0 0 0 0 0 0 ] 0.7;
Cmix Cmix [ 0 0 0 0 0 0 0 ] 1;

Hi NirA,

I guess it is the same as reactingFoam which uses Chalmers turbulent combustion model. It calculates the reaction rate based on the chemical time scale (from ODE solver) and the turbulent time scale (kolomogrov time scale) then it calculates K which is a function of Cmix. You can check the chemistry and readchemistryproperties files in the solver folder.
I hope that will answer your equation.

Hi Hassan,

Thanks. Do you know which .C and .H files are involved to calculate these modified reaction rates. I am trying to locate these files and have hard time tracking it back. partly because still I am a novice in C++ and OpenFoam.

Nir

in the solver folder for example (reactingFoam);

OpenFOAM/ applications/ solvers/combustion/ reactingFoam

you will find reactingFoam.C which is the main solver file contains the C++ main function.
you will find also file called chemistry (where are reaction rate calculation) and readchemistryproperties (where turbulent switch exist)

If anything not clear don't hesitate to ask.

Thanks Hassan,

Now I know where the reaction rates are being modified to account for turbulence.


Thanks,
Nir

You can find more about the model in Chalmers PhD thesis on the following link;

http://powerlab.fsb.hr/ped/kturbo/OpenFOAM/docs/
FabianPengKarrholmPhD2008.pdf
NilssonYokohamaOct2006.pdf

you can see also this paper FLAME LIFTOFF IN DIESEL SPRAYS

combustion flow simulation on liquid rocket thrust chambers
 

HI...
My objective is to simulate the realistic flow involving combustion of propellant(i.e.liquid fuel and liquid oxidiser)with cooling ,Thus exploring the capabilities of CFD tool and demonstrating its usefulness in supporting the design and optimization process of modern rocket engines.
is there a facility in fluent 6.3.26 for liquid-liquid impingement flame jet or limited to "liquid fuel and gaseous oxidiser" only?
can i get all the performance parameters, temperature,pressure,spatial spray distribution, droplet diameter,thrust obtianable.....
i was going through fluent tutorials can i solve this as"EQUILIBRIUM CHEMISTRY MODEL of NON PREMIXED,NON ADIABATIC,UNSTEADY LAMINAR FLEMELET with SINGLE MIXTURE FRACTION COMBUSTION PROBLEM?
Please someone suggest me with some idea to slove this problem...
thank you for spending ur precious time.
regards,
Honey.