CFD Online Logo CFD Online URL
Home > Forums > OpenFOAM Running, Solving & CFD

Problems on H2/air CFX simulation

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

LinkBack Thread Tools Display Modes
Old   April 14, 2009, 03:28
Question Problems on H2/air CFX simulation
New Member
Join Date: Apr 2009
Posts: 4
Rep Power: 8
xulixian is on a distinguished road
am puzzled by the simulation of H2/air combustion using CFX. I could not get the expected temperature, the maximum flame temperature is always below 980K. I use stoichiometric mixture of hydrogen and air, but after the reaction, their always a lot of O2 left. It looks like a lean combustion. And the in the beginning of the simulation, CFX tell me
Reactants and products do not balance for a reaction.
| Products will not be scaled for conservation of mass. |
| |
| Reaction : Hydrogen Oxygen |
| Products scale = 2.7750
My reaction chamber is a tube with 0.2 mm in diameter and 1.55mm in length, the inlet diameter is 0.1mm. Adiabatic wall condition.The boundary is the following:

Inlet: 300K, 6 m/s, Mass fraction H2: 0.02857 O2: 0.22857 N2: constraint,

Outlet: static pressure 1 bar

Initial temperature: 1000K

I use the default stoichiometric coefficient, so the reaction is H2 + 0.5 O2 = H2O,

Pre-Exponential Factor : 3.12e7 [m^1.5 s^-1 mol^-0.5] **(the value in Fluent is 9.87e8, I change the value since I have to switch the uint from "kmol" in Fluent to "mol" in CFX.)
Temperature Exponent : 0
Activation Energy : 3.1e+04 j/mol.

In the begining of the simulation, I use the time step of 1 e-7 s, then I increase the time step to 1 e-5 s.

Can you help me to diagnose the simulation? I appreciate for your help.
xulixian is offline   Reply With Quote

Old   April 14, 2009, 14:29
New Member
Kerstin Heinen
Join Date: Mar 2009
Location: Ludwigshafen, Germany
Posts: 27
Rep Power: 8
kerstin is on a distinguished road
you should read the thread about wall heat flux in CFX answered by Bernhard.

Seems to become more and more people stumbling in the wrong forum. So we can start having fun now? ;-)
kerstin is offline   Reply With Quote

Old   April 14, 2009, 15:00
New Member
Join Date: Apr 2009
Posts: 4
Rep Power: 8
xulixian is on a distinguished road
Hi Kerstin,
thank you for your reply. Acctually I proposed my question in CFX forum, but I didn't get any answers from them, so I tried my luck here, and it looks not bad! ^_^
I will check the thread you mentioned. thanks again.

regards, Lixian
xulixian is offline   Reply With Quote


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
which s/w for turbine simulation, Fluent/ CFX ? Parag FLUENT 0 March 8, 2007 03:28
Simulation of turbine cascade in CFX. Jonas Pedro Caumo CFX 0 December 9, 2006 14:54
Problems modeling CONTACT SURFACES with CFX Mesh MAldaz CFX 2 September 12, 2006 17:10
problems of turbo simulation in CFX-10 Qiang CFX 0 September 11, 2006 23:19
Problems in CFX 5.5.1 Sulviyanti CFX 6 February 7, 2003 17:46

All times are GMT -4. The time now is 20:21.