CFD Online Logo CFD Online URL
www.cfd-online.com
[Sponsors]
Home > Forums > OpenFOAM Running, Solving & CFD

Combustion

Register Blogs Members List Search Today's Posts Mark Forums Read

Like Tree3Likes

Reply
 
LinkBack Thread Tools Display Modes
Old   May 3, 2005, 07:20
Default Hi Ervin, What about the me
  #41
Member
 
Tommaso Lucchini
Join Date: Mar 2009
Posts: 80
Rep Power: 7
lucchini is on a distinguished road
Hi Ervin,

What about the mesh?
how did you create it?
what is its size?
is the cylinder axis aligned as the z one?
are the measurements units of the mesh in meters?

Try like this: in the -180 directory of your case copy from the dieselFoam aachenBomb tutorial case the fields:
-N2
-O2
and fix as zeroGradient the boundary conditions for piston, liner and cylinderHead.

Then from the engineFoam tutorial kivaTest copy the fields:
-k
-epsilon
-T
-U
-p
and copy also the controlDict file from the /system directory in the /system directory of your case.
modify the controlDict file imposing:

adjustTimeStep yes;
maxCo 0.1;
maxDeltaT 1;

For what concerns the temperature you can, for the beginning, use the zeroGradient condition.
If the mesh is OK everything MUST work well at least till the beginning of injection.
good luck.ciao
tommaso
lucchini is offline   Reply With Quote

Old   May 3, 2005, 07:58
Default Hi Tommaso, Thank you for y
  #42
Member
 
Ervin Adorean
Join Date: Mar 2009
Posts: 67
Rep Power: 7
adorean is on a distinguished road
Hi Tommaso,

Thank you for your answers.

I have created the mesh with Gmsh. The cylinder axis is the z axis. The units are meters.

What about fvSchemes and fvSolution? Which ones should I use?
Now it is complaining that the Ydefault is missing from the -180 time directory.

Thanks.

Ervin
adorean is offline   Reply With Quote

Old   May 3, 2005, 08:02
Default And after I add it, I've got a
  #43
Member
 
Ervin Adorean
Join Date: Mar 2009
Posts: 67
Rep Power: 7
adorean is on a distinguished road
And after I add it, I've got a segmentation fault error.
What else is wrong?
adorean is offline   Reply With Quote

Old   May 3, 2005, 11:44
Default Hi all! I was wondering if so
  #44
Member
 
Tommaso Lucchini
Join Date: Mar 2009
Posts: 80
Rep Power: 7
lucchini is on a distinguished road
Hi all!
I was wondering if someone can give me some references about models that describe the flame kernel formation and growth in turbulent combustion and in spark-ignition engines.
thanks in advance.
ciao
tommaso
lucchini is offline   Reply With Quote

Old   May 3, 2005, 12:16
Default About fvSchemes and fvSolution
  #45
kärrholm
Guest
 
Posts: n/a
About fvSchemes and fvSolution, there's a manual for OpenFOAM in the

/OpenFOAM/OpenFOAM-1.1/doc/Guides-a4

On page 25 of Userguide.pdf there's a short description of the two files, but there's more if you read further.

/Fabian
  Reply With Quote

Old   May 13, 2005, 04:49
Default Hi! I have a question about
  #46
Member
 
Tommaso Lucchini
Join Date: Mar 2009
Posts: 80
Rep Power: 7
lucchini is on a distinguished road
Hi!

I have a question about how StCorr is calculated. In the file StCorr.H everything is OK till Vk and Ak are calculated. It's quite difficult for me to understand how AkEst is calculated.

mgb is defined like this....

volScalarField mgb = fvc::div(nf, b, "div(phiSt,b)") - b*fvc::div(nf) + dMgb;

according to what is written after...

dimensionedScalar AkEst = gSum(mgb*mesh.V());

mgb should be the flame area per unit volume, in fact according to how the surfaceScalarField nf is defined where there is no flame (b=0 or b=1) nf is zero.

but I have some difficulties in understanding how the formula to calculate mgb is obtained.

Thanks for any kind of explanation.
regards.
tommaso
lucchini is offline   Reply With Quote

Old   June 1, 2005, 13:14
Default Hi all, For comparison with
  #47
Member
 
Ervin Adorean
Join Date: Mar 2009
Posts: 67
Rep Power: 7
adorean is on a distinguished road
Hi all,

For comparison with experimental results, can the lift-off length, liquid length and flame tip penetration be computed and saved in a results file in dieselFoam?

Or, are there other variables used for validation of dieselFoam/dieselEngineFoam results?

Thanks,

Ervin
adorean is offline   Reply With Quote

Old   June 2, 2005, 03:18
Default the dieselSpray class has a li
  #48
Super Moderator
 
niklas's Avatar
 
Niklas Nordin
Join Date: Mar 2009
Location: Stockholm, Sweden
Posts: 691
Rep Power: 18
niklas will become famous soon enough
the dieselSpray class has a liquid length penetration function that you can use.

dieselSpray.liquidPenetration(prc)

where prc is the percentage of how much of the liquid you want to use for defining the liquid penetration.

so if you use

dieselSpray.liquidPenetration(1.0)

it will use all of the liquid to calculate the penetration, but if you use

dieselSpray.liquidPenetration(0.98)

it will not use the 2% most far away from the injector.

the other parameters, you have to calculate/define yuorself.

N
niklas is offline   Reply With Quote

Old   November 4, 2005, 16:22
Default Hello, I am trying kivatest
  #49
New Member
 
frederic.deghetto@free.fr
Join Date: Mar 2009
Location: Saint Brévin, France
Posts: 3
Rep Power: 7
frederic is on a distinguished road
Hello,

I am trying kivatest with OpenFoam-1.2.

I get the following error:
FOAM FATAL ERROR : attempt to use janafThermo<equationofstate> out of temperature range

Does the bug of fixed temp always exist ?

Thanks you,

Fred
frederic is offline   Reply With Quote

Old   December 6, 2005, 07:57
Default Hello, I have also tried th
  #50
Member
 
Guido Adriaensen
Join Date: Mar 2009
Posts: 56
Rep Power: 7
guido_adriaensen is on a distinguished road
Hello,

I have also tried the kivatest in OpenFOAM-1.2, again I get the error of the temperature out of range. As Henry Weller mentioned in his post of Wednesday, March 23, 2005 - 01:41 am, the problem is related to the hhu* thermodynamics packages. This would be fixed in version 1.1.1. Could It be that version 1.2 does not have this fix?? If so, is the fix available? I would really like to have it.

thanks,

Guido
guido_adriaensen is offline   Reply With Quote

Old   December 6, 2005, 11:45
Default Hi Guido, The 1.2 version has
  #51
Member
 
Tommaso Lucchini
Join Date: Mar 2009
Posts: 80
Rep Power: 7
lucchini is on a distinguished road
Hi Guido,
The 1.2 version has been fixed concerning the hhuCombustion thermo package.
You can get this error for several different reasons, and the most common is because you are using a too large time step. You can see in the kivaTest/system directory that you have two different controlDicts (controlDict.1st and controlDict.2nd), one is for compression and the other one is for combustion/expansion.
To get the case running try to reduce the time step during the combustion phase, or try to limit to (for example) 0.1 the value of the Courant Number, setting in the controlDict file the following variables:
adjustTimeStep on;
maxCo 0.1;
maxDeltaT 0.5;
I hope this should work.
Regards.
Tommaso
lucchini is offline   Reply With Quote

Old   December 7, 2005, 10:29
Default Ciao tutti Thx Tommaso for
  #52
Member
 
Guido Adriaensen
Join Date: Mar 2009
Posts: 56
Rep Power: 7
guido_adriaensen is on a distinguished road
Ciao tutti

Thx Tommaso for your reply. I have made the adjustments to the controlDict file. To be honoust, I thought I had run the kivaTest-file allready for a maximum courant number of 0.1, but after I checked it, I saw it was not configured for maximum courant number.
Sorry my mistake. :-)

Currently I'm working on a two-stroke engine, has anybody ever done a simulation for this type of engine with OpenFOAM??, if so I would gladly get into contact with that person. I'm having trouble implementing the inlet and outflow channels in the cylinderwall. They are moving with my mesh, instead of being at a fixed location. I'm currently looking at the mixer tutorial and the TJunction tutorial from Hrvoje, thx again for that! :-). When I make progress I will report this here.


regards
Guido
guido_adriaensen is offline   Reply With Quote

Old   December 19, 2005, 02:28
Default Hello, I still run in to th
  #53
Member
 
Guido Adriaensen
Join Date: Mar 2009
Posts: 56
Rep Power: 7
guido_adriaensen is on a distinguished road
Hello,

I still run in to the problem of the temperature range for the kivatest under version 1.2, even though I fixed the maximum courant number to 0.75. With smaller timesteps the problem is delayed, but sooner or later it kicks in. Is there something else I'm missing here? Any help will be welcome. Thx

Guido
guido_adriaensen is offline   Reply With Quote

Old   December 21, 2005, 04:37
Default Hello Everybody, Sorry for
  #54
Member
 
Guido Adriaensen
Join Date: Mar 2009
Posts: 56
Rep Power: 7
guido_adriaensen is on a distinguished road
Hello Everybody,

Sorry for bothering you again, but I have a question concerning the ignition parameters defined in the ignitionSites file. The location is obvious :-), diameter is the diameter of the ignition spark, start is the starttime in degrees for ignition, duration is the time (again in degrees) for the ignition to last (in kivaTest tutorial 20 degrees, is this not too long? It seems rather long to me). If I got it wrong please let me know. The strength though is not that clear to me, what does it specify? I could not really find where it is used. If anybody could help me with this I would appreciate any hints.
Thanks all, I hope to be able to contribute some for you guys soon!

regards
Guido
guido_adriaensen is offline   Reply With Quote

Old   January 22, 2006, 23:14
Default Hi, David! I actually imple
  #55
Member
 
Masashi IMANO
Join Date: Mar 2009
Location: Tokyo, Japan
Posts: 34
Rep Power: 7
imano is on a distinguished road
Hi, David!

I actually implemented rough wall functions, but my implementation couldn't handle non-uniform roughness and
was very ad-hoc like this:

src/turbulenceModels/incompressible/wallFunc/wallViscosityI.H:

if (yPlus > yPlusLam_)
{
if ((curPatch.name().count('~'))==2) {
nutw[facei] =
nuw[facei]
*(yPlus*kappa_.value()/(log(y_[patchi][facei]/z0_.value())) - 1.0);
} else if ((curPatch.name().count('^'))==2) {
nutw[facei] =
nuw[facei]
*(1.0/alpha_.value() - 1.0);
} else {
nutw[facei] =
nuw[facei]
*(yPlus*kappa_.value()/log(E_.value()*yPlus) - 1);
}
}

So I'm afraid my code would not help you...

Masashi
imano is offline   Reply With Quote

Old   April 4, 2006, 09:18
Default Hi, I am trying to modelise a
  #56
julienh
Guest
 
Posts: n/a
Hi,
I am trying to modelise a bluff body flamme (Sandia laboratories) using reactingFoam
After 0.041 sec, I get this message :

FOAM FATAL ERROR : attempt to use janafThermo<equationofstate> out of temperature range 200 -> 5000; T = 145

From function janafThermo<equationofstate>::checkT(const scalar T) const
in file /home/dm2/henry/OpenFOAM/OpenFOAM-1.2/src/thermophysicalModels/specie/lnInclude/ janafThermoI.H at line 73.

How can I use the functions wallAdiabatic or wallFixedTemp ? It does not work in boundary conditions.

Best regards

Julienh
  Reply With Quote

Old   July 25, 2006, 21:34
Default Hi. I'm starting to use Ope
  #57
atsushi
Guest
 
Posts: n/a
Hi.

I'm starting to use OpenFOAM, and please help me.

What kind of fuels i can use in engineFoam?

Only 3 fuels(IsoOctane,Methane,Propane)??

Can I use DME...?

Please someone help me.

Atsushi
  Reply With Quote

Old   July 26, 2006, 09:44
Default Hi Atsushi, you can use DME i
  #58
Member
 
Tommaso Lucchini
Join Date: Mar 2009
Posts: 80
Rep Power: 7
lucchini is on a distinguished road
Hi Atsushi,
you can use DME if you have the Gulder's coefficients for this kind of fuel (put them in combustionProperties) and also the thermophysical properties (to be set in thermophysicalProperties).
Do you want to simulate DME in a spark-ignition engine? I knew DME was used in diesel engines....
bye
Tommaso
lucchini is offline   Reply With Quote

Old   August 6, 2006, 22:04
Default Hi Tommaso, I knew DME w
  #59
atsushi
Guest
 
Posts: n/a
Hi Tommaso,


I knew DME was used in diesel engine but I want to simulate in a SI engine.

Thank you for your help!!
I'll try it.

Atsushi
  Reply With Quote

Old   August 13, 2006, 23:12
Default Hi everyone, I try to model
  #60
atsushi
Guest
 
Posts: n/a
Hi everyone,

I try to model SI engine using engineFoam.
When I change cylinder size, read blockMesh(not to read otape17), and run engineFoam, I get this error;

FOAM FATAL ERROR : attempt to use janafThermo<equationofstate> out of temperature range 200 -> 6000; T = 0

From Function janafThermo<equationofstate>::checkT(const scalar T) const
in file: /home/dm2/henry/OpenFOAM/OpenFOAM-1.3/src/thermophysicalModels/specie/lnIncl ude/janafThermoI.H at line: 73.

FOAM aborting


Every parameter remains default except for the value of cylinder size.
I suppose that temperature T is not correctly worked.

Please someone teach me how should I do.
Any help will be welcome.
Thanks.
  Reply With Quote

Reply

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On


Similar Threads
Thread Thread Starter Forum Replies Last Post
combustion model in premixed combustion chamber wuyu FLUENT 6 March 26, 2014 14:58
Hydrogen Air combustion in a combustion chamber popi CFX 7 July 11, 2007 18:40
Sawdust Combustion-Non-premixed Combustion Model Jessy FLUENT 1 June 19, 2007 10:59
combustion in internal combustion engine George Main CFD Forum 0 September 7, 2006 14:41
combustion prasat Main CFD Forum 1 June 16, 2003 13:17


All times are GMT -4. The time now is 06:28.