|
[Sponsors] |
![]() |
![]() |
#21 |
New Member
Ilja Sabelfeld
Join Date: Nov 2009
Posts: 22
Rep Power: 16 ![]() |
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 |
|
![]() |
![]() |
![]() |
![]() |
#22 |
New Member
David Huckaby
Join Date: Jul 2009
Posts: 21
Rep Power: 16 ![]() |
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 |
|
![]() |
![]() |
![]() |
![]() |
#23 |
New Member
Ilja Sabelfeld
Join Date: Nov 2009
Posts: 22
Rep Power: 16 ![]() |
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 |
|
![]() |
![]() |
![]() |
![]() |
#24 |
New Member
Ilja Sabelfeld
Join Date: Nov 2009
Posts: 22
Rep Power: 16 ![]() |
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 |
|
![]() |
![]() |
![]() |
![]() |
#25 |
New Member
David Huckaby
Join Date: Jul 2009
Posts: 21
Rep Power: 16 ![]() |
Ilja,
there is a steady chemistry solver which is part of alternateReactingFoam package written by Gschaider et al. . See the following links for more info: http://www.openfoamwiki.net/index.ph...ateReactinFoam https://openfoam-extend.svn.sourcefo...mistry/Steady/ The steady solver can be compiled independently of the other packages. You may need to modify Make/options to get it to compile with OF 1.6/1.6.x as well as the the input files to get the tutorials to run correctly. The standard reactingFoam files should provide some guidance on this. Dave Dave |
|
![]() |
![]() |
![]() |
![]() |
#26 |
New Member
mehdi
Join Date: Jun 2009
Posts: 7
Rep Power: 16 ![]() |
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? |
|
![]() |
![]() |
![]() |
![]() |
#27 | |
Senior Member
Hassan Kassem
Join Date: May 2010
Location: Germany
Posts: 242
Rep Power: 18 ![]() |
Quote:
|
||
![]() |
![]() |
![]() |
![]() |
#28 |
New Member
Silvano
Join Date: Aug 2010
Location: Chicago /Torino Us/Italy
Posts: 11
Rep Power: 15 ![]() |
||
![]() |
![]() |
![]() |
![]() |
#29 |
Senior Member
Hassan Kassem
Join Date: May 2010
Location: Germany
Posts: 242
Rep Power: 18 ![]() |
||
![]() |
![]() |
![]() |
![]() |
#30 |
New Member
Silvano
Join Date: Aug 2010
Location: Chicago /Torino Us/Italy
Posts: 11
Rep Power: 15 ![]() |
||
![]() |
![]() |
![]() |
![]() |
#31 |
Senior Member
Hassan Kassem
Join Date: May 2010
Location: Germany
Posts: 242
Rep Power: 18 ![]() |
||
![]() |
![]() |
![]() |
![]() |
#32 |
Member
N. A.
Join Date: May 2010
Posts: 64
Rep Power: 16 ![]() |
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 |
|
![]() |
![]() |
![]() |
![]() |
#33 | |
Senior Member
Hassan Kassem
Join Date: May 2010
Location: Germany
Posts: 242
Rep Power: 18 ![]() |
Quote:
There are many combustion models in OpenFOAM. You can run the available tutorials in OpenFOAM. For Q1, I cannot understand what do you mean? |
||
![]() |
![]() |
![]() |
![]() |
#34 |
Member
N. A.
Join Date: May 2010
Posts: 64
Rep Power: 16 ![]() |
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; |
|
![]() |
![]() |
![]() |
![]() |
#35 |
Senior Member
Hassan Kassem
Join Date: May 2010
Location: Germany
Posts: 242
Rep Power: 18 ![]() |
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. |
|
![]() |
![]() |
![]() |
![]() |
#36 |
Member
N. A.
Join Date: May 2010
Posts: 64
Rep Power: 16 ![]() |
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 |
|
![]() |
![]() |
![]() |
![]() |
#37 |
Senior Member
Hassan Kassem
Join Date: May 2010
Location: Germany
Posts: 242
Rep Power: 18 ![]() |
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. Last edited by hk318i; August 24, 2010 at 19:54. |
|
![]() |
![]() |
![]() |
![]() |
#38 |
Member
N. A.
Join Date: May 2010
Posts: 64
Rep Power: 16 ![]() |
Thanks Hassan,
Now I know where the reaction rates are being modified to account for turbulence. Thanks, Nir |
|
![]() |
![]() |
![]() |
![]() |
#39 |
Senior Member
Hassan Kassem
Join Date: May 2010
Location: Germany
Posts: 242
Rep Power: 18 ![]() |
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 |
|
![]() |
![]() |
![]() |
![]() |
#40 |
New Member
sri
Join Date: Aug 2010
Posts: 8
Rep Power: 15 ![]() |
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. |
|
![]() |
![]() |
![]() |
|
|
![]() |
||||
Thread | Thread Starter | Forum | Replies | Last Post |
Natural convection - Inlet boundary condition | max91 | CFX | 1 | July 29, 2008 20:28 |
Laminar flow or Turbulent flow | mech | FLUENT | 0 | January 27, 2007 18:51 |
laminar and turbulent flow in one simulation | msna | FLUENT | 0 | January 27, 2007 17:35 |
Reynolds and Turbulent Flow | Frederic Dubinski | Main CFD Forum | 2 | October 20, 2004 13:57 |
PhD in turbulence | Hans | Main CFD Forum | 14 | October 8, 2001 03:03 |