Macro opening problems
 

Hello,

I'm running star-CD on my Win-XP computer. My problem is, I can't save my written macros on the working directory, and when I copy an old macro into this directory I can't see them.I can only save and open macros in the Global directory, but any time I have to set environmental variables. I had contact with cd-adapco customer service but, I couldn't get any solution for it. Please help me, If you know solution for this problem. Thanks in advance for your help.

Best Regards, Mehdi

Re: Macro opening problems
 

Hi Mehdi,

I had a same problem and I did not care to contact cd-adapco(noreply customer sevice). By the way how your combustion temp. is after changing default EBU values.

The reason for asking is I am also using the same premix combustion model and I have few questions if you want to help me.

Thanks a lot.

Re: Macro opening problems
 

Hello, About combustion temperature, I couldn't reach to correct temperature with my model, then I built a very simple model and simulate the flow and combustion. The model gave me good results. Then I built again my geometry and now I'm running simulation, but I'm not so hopeful, you know star-CD always can surprise you:) If you had problem feel free and ask.

Good luck, Mehdi

Re: Macro opening problems
 

Hi Mehdi,

I really appreciate your reply.

My flow is terbulent, compressible with combustion and moving mesh. It would be a great help for me if you can clear this doubts.

1) In the molecular properties panel how do I specify my material. I am using premixer of propane(V) and air as my fuel but I am specifying air only with Cp-polinomial of temp. in this panel. Am I doing it right?

2) In the initialization of air panel,I am not giving ANY parameter. do I need to specify turbulence again? I specified turbulence in boundary condition panel.

3) In the ignition panel how should I calculate fraction Burnt?

Thank you very much and good luck.

Re: Setting for premixed combustion models
 

Hi,

1) For your first question, In the molecular panel you can select the properties of background material, in your case you have air, then if you want to model combustion you should go to additional scalars and select each scalars from database. select first one for Propane and other after that.

2) If you know you can put some acceptable value for turbulence there, that helps for faster converge.

3)As I undrestood, model can find the place which ignition will happen. This choice only helps for starting of simulation and put acceptable value for that, but don't be worry about correctness of that.

Good luck, Mehdi

Re: Setting for premixed combustion models
 

Hi Mehdi,

Bunch of thanks for your reply.

I am doing pretty much same as you have advised but never found proper results. I was not giving turbulence in Intialisation panel. And I use value of mass fraction of propane as a value of fraction burnt in the ignition panel.

I will keep you abreast of any results. Thanks once again.

Re: Setting for premixed combustion models
 

Hello again,

Be carefull, In the reaction system panel, put mixture fraction of fuel ( or mass fraction in your case) in the mixture fraction box. I think the burnt mixture doesn't mean the mass fraction, it means how much fuel/ total fuel has been burnt, but any way it should n't be so important. Check the values of scalars and select them from list in the code, also check the BC panel for scalars. If you didn't reach to right result, check the results in the plots and see the mass fraction of scalars. if you didn't reach to any acceptabale result, I think it is good to make a very simple model, one inlet and outlet in laminar case and set the model with correct parameter.

Good Luck, Mehdi

Re: Setting for premixed combustion models
 

Hi Mehdi,

I appreciate your quick response.

In the ignition panel, why it takes ignition temperature as zero automatically? Is it proper? I get scalar values different than I specified in the initialisation panel under liquids and gases panel. Do you have any idea?

I do not know the reason for these errors- #007 setting T at cell...,#066 temp. less than specified found at cell...,#067 temp. greater than specified fuond at cell....

I am grateful to you.

Re: Setting for premixed combustion models
 

There is no temperature in ignition panel, I talk about EBU model, maybe your model is different.

Intial values are for starting simulation. In which stage you check them, becasue after running simulations they can change,

Sorry, I don't about that error.

Re: Setting for premixed combustion models
 

Hello Mehdi,

I am also talking about EBU Standard. If you see command executed in command window it displays temp. as zero but any way when this model worked fine for you, it must for me also. May be I am doing something wrong somewhere.

Thanks alot Mehdi.

Re: Setting for premixed combustion models
 

Hello,

My model just working but the results are not correct, I have high temperature and I need to adjust it but I do not know how, By the way, If you could not slove the problem, I can send you a simple test case for EBU and you can check the settings.

Re: Setting for premixed combustion models
 

hi all

i am working with Gasoline direct injection system. All these days i worked with cold flow only, can you help to set starguide panel for GDI engine combustion

advance thanks STAR user

Re: Setting for premixed combustion models
 

Hi,

I would love to do that. It will serve me two ways. It will help me cure my model and if I was doing right, I will be more confident about the settings and will be able to concentrate on loop holes. Please let me know the place where you upload your model.

I really really appreciate your help.

Re: Setting for premixed combustion models
 

I put it in the following address, I hope you can find it:

http://www.badongo.com/file/532046

Good Luck

Re: Setting for premixed combustion models
 

Hi Mehdi,

I have received your model. Thanks alot for that. I shall inform you the results.

Re: Setting for premixed combustion models
 

Hi Mehdi,

It worked. I have better temp. but still face co2 in the begining of combustion.

I really really appreciate your help.

Re: Setting for premixed combustion models
 

That's very good.

Good Luck, Mehdi

Re: Setting for premixed combustion models
 

dear all

I am working with GDI engine geometry, and i don't know how start with combustion in STAR CD ....as i am injecting fuel should go for non premixed or partially premixed, and which reaction model i should use. Please guide me for my combustion analysis

one question reg. advanced combuston tutorial, in tut geo is 45deg sector and it is a diesel engine combustion, but they initilized with 100bar and 950k ( i hope 100 bar is too high value) and once i go for combustion run i am getting 106bar as max pressure, which is not much significant rise.... i have doubt whether i am doing any mistake or STAR CD is not good for combustion

advance thanks STAR USER

Re: Setting for premixed combustion models
 

Hi,

Which combustion model you are using,PPDF? I would say ch-9 and ch-10 of methodology would be a good idea. And not to forget ch-12 of uguide.