hi, everyone I can not utilize the combuestion model in CFX5.5. I can not use it to calculate the combuestion of multicomponent gas fuel. The component of gas fuel is a mixture of low molecular weight hydrocarbon including olefin, ethane, propane, butane, etc. The problem seems to be so easy to handle CFX4.3. But I do not know how to solver it in CFX5.5

Hi Ray, have you completed the Combustion tutorial (#18)? Regards, Mike

Dear Mike: Thank you at first. But I think I did not express clearly which problem I must solver. The Combustion tutorial (#18) is very simple. And the gas fuel is just one combustible component--methane. The mixture in tutorial (#18) is the air and the methane. But THE multicomponent gas fuel what I refered to is the methane and other combustible component like butane, ethene, etc. THE multicomponent gas fuel does not include the combustion-supporting like air and oxidant. Maybe I did not utlize the tutorial efficiently. Then can you give me a hand ?

Have a look in the <CFXROOT>/etc/5.5.1/REACTIONS file - hopefully this should be of some help?

I have tried but failed again. Have you done something about this? If it is ,Tell me how you do to solver the problem, Please,

Hi Ray, sorry - i haven't ever tried to set a case similar to the one you describe. I believe the REACTIONS file allows you to define custom reactions, but i haven't tried to do this. Hopefully somebody else on here will know more. Regards, Michael

Then who can help me ?

The reaction/combustion modeling in CFX-5 is a little different than in CFX-4. In CFX-5, there is no limit to the number of fuels and oxidants you can solve in a single calculation; you simply include the species you want to model for each reaction.

If you want to model more than one reaction, then you include multiple reactions within a single reacting fluid which contains all the required species. Additionally, if you want to model a reaction in a number of steps, you can include the steps within a single reaction.

Admittedly, the tutorial in the CFX-5 manual is a little limited since it only deals with a simple one step reaction.

I would take Michael's advice and familiarise yourself with the REACTIONS file, and the Command File of the tutorial. This should give you all you need to model your physical situation.