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-   -   Premixed Combustion (http://www.cfd-online.com/Forums/fluent/32804-premixed-combustion.html)

IS January 5, 2004 18:37

Premixed Combustion
 
Once again I need help, this time in premixed combustion model. These are the questions that I have:

1) For the premixed combustion I am using the following models :

a) Radiation--->Rosseland

b) Energy

c) species-->Premixed

d) Viscous----> k-E

Do I need to switch on anything more?

2) My combustion chamber has inlet as (one) mass flow inlet and outlets are several pressure outlet.

--- My question is: if I set the progress variable (c)as zero in inlet and c=1 at outlet, do I need to specify the the inlet temperature as room temperature?

or

---- Should i set the progress variable as c=1 in inlet and c=1 in outlet and specify the inlet temperature above the ignition temperature of methane?

Please advice (as soon as you can) on this as I am confused and do not understand how fluent simulates the spark in combustion process.

Thanks;

tom January 7, 2004 05:21

Re: Premixed Combustion
 
HI,

You need to set the inlet progress variable to 0 and the outlet variable to 1, where 0 indicates an unburnt mixture and 1 is burnt. Set the inlet temperature to what it is would be in reality - so in your case there is no preheating and the inlet air supply will be at room temperature. To initialize combustion you need to patch a high temperature zone of the fluid above the ignition temperature of the mixture. This you do after initializing the solution. In your case, assuming you have a stoichiometric mixture a temperature of around 1200K should be enough.

I hope this is what you were looking for!

Tom

IS January 7, 2004 10:44

Re: Premixed Combustion
 
Hi Tom

Thanks a lot for your useful suggestion. I have two more question on this problem. In this problem the mixture is composed of methane and air (volume of air is 13 times the volume of methane), mixture enters at room temperature and ignites in the combustion chamber.

When selecting the material (fluid) properties in Fluent, can I select just methane (pre mixed combustion) properties ?

or I should define the properties of the mixture ie Methane + Air ?

If I have to define the properties of the mixture, is there a way to use Fluent material database and do this.

The objective of my work is to determine the temperature distribution in the combustion chamber. I do not intend to inject particles in the combustion chamber, but do I still need to turn the Defne-->Model---->discrete phase-ON in Fluent?

Tom please advise on the above, I need help.

Thanks once again

combustione July 9, 2010 20:22

have you solved your problems?


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