CFD Online Logo CFD Online URL
www.cfd-online.com
[Sponsors]
Home > Forums > CFX

Combustion in a Back ward facing step

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

Reply
 
LinkBack Thread Tools Display Modes
Old   June 22, 2011, 10:11
Default Combustion in a Back ward facing step
  #1
Member
 
Mina
Join Date: Apr 2011
Posts: 88
Rep Power: 6
Mina_Shahi is on a distinguished road
Dear All

I am trying to model combustion in a back ward facing step for propane air mixture and then compare the result by Robert W Pitz and John W.Daily but the flame shap is really depended on initial condition. First i am doing steady state simulation for Propane Air WD1.
First i had problem because the mixture didn't ignite, then i divided the domain to two region and set higher temperature in ignition domain close to the step.
but still the flame shap is different with that of the paper.
Can some one please help me?

Mass fraction of C3H8 = 0.077
Mass fraction of O2=0.4912

Two regions.jpg

Temperature.jpg
Mina_Shahi is offline   Reply With Quote

Old   June 27, 2011, 05:52
Default Source point in combustion modeling
  #2
Member
 
Mina
Join Date: Apr 2011
Posts: 88
Rep Power: 6
Mina_Shahi is on a distinguished road
Dear All

Does any body know about source point? actually i am looking for other way to ignite my mixture because i think ignition zone or using two regins is not good way. i am trying to use source point but i don't know how. can you please some body help me.
Mina_Shahi is offline   Reply With Quote

Old   July 10, 2011, 19:57
Default try auto-ignition option
  #3
New Member
 
maegasturbine
Join Date: Jul 2011
Posts: 1
Rep Power: 0
maesims is on a distinguished road
Hi,
Are you using the eddy dissipation model? Try using auto ignition and you should be able to get the mixture ignited.
The other way of doing it is you can initialize the domain and use a very small value for CO2.mf or H2O.mf = 0.00001 and then run your sim.
You should not require multiple domains to ignite.

Thanks.
maesims is offline   Reply With Quote

Old   July 19, 2011, 05:36
Default
  #4
Member
 
Mina
Join Date: Apr 2011
Posts: 88
Rep Power: 6
Mina_Shahi is on a distinguished road
Hi

Many Thanks.
Indeed i am using eddy dissipation and also Finite rate chemistry model and BVM.
You mean first i should put both fresh mixture and burnt mixture as an initial value (CO2.mf or H2O.mf = 0.00001 )?
i need multiple domains because when i set higher temperature in the whole domain it will be diverged , so i set two domains one which i call ignition zone has higher temperature. but this is not also a good way because in this way the flame will be confined in this domain.

I will appreciate if you can give me advice
Mina_Shahi is offline   Reply With Quote

Old   July 19, 2011, 05:37
Default Re: auto-ignition option
  #5
Member
 
Mina
Join Date: Apr 2011
Posts: 88
Rep Power: 6
Mina_Shahi is on a distinguished road
Hi

Many Thanks.
Indeed i am using eddy dissipation and also Finite rate chemistry model and BVM.
You mean first i should put both fresh mixture and burnt mixture as an initial value (CO2.mf or H2O.mf = 0.00001 )?
i need multiple domains because when i set higher temperature in the whole domain it will be diverged , so i set two domains one which i call ignition zone has higher temperature. but this is not also a good way because in this way the flame will be confined in this domain.

I will appreciate if you can give me advice
Mina_Shahi is offline   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
Backward facing step; x/H; U/U0; diemsionless analysis; paraview idrama OpenFOAM 1 December 3, 2013 18:10
__Backward Facing Step simulation problems__ maysmech OpenFOAM 2 February 11, 2011 16:20
backward facing step problem ian8430 Main CFD Forum 1 January 18, 2011 09:58
Rearward facing step simulations siw FLUENT 1 September 23, 2009 02:21
Backward Facing Step with Blowing azar Main CFD Forum 1 November 16, 2006 02:01


All times are GMT -4. The time now is 09:52.