[VictorC]

Hi everyone,

I am modeling a methane gas burner. I managed to get the cold flow running with no issues, but when I try to add combustion there is no reaction. Because of this I decided to do a very simple model to try to get combustion running on that one before doing it in my main model.

For the simple model I have a very simple geometry. It is essentially cylinder with three equal diameter sections. My aim to the start the combustion on the second section of the cylinder.

My setup is as follows:

• Species Transport Model with Finite-Rate Chemistry
• Mixture Material: Methane-Air
• Inlet: T=300K; mole fractions of CH4=0.0872, O2=0.1918, N2=0.721

What I have done so far:

• Running the cold flow until it converges
• To initiate reaction patching the mid-section of the cylinder with T=2000K and reactants+products.

My problem is that no reaction occurs, the solution is the same as the one with cold flow (no temperature increase, no combustion species present). However if I change the inlet temperature to 1500K the reaction starts from the inlet. This makes me guess that my setup is working, but for some reason the patching is not. What am I doing wrong? Why the reaction is not starting by patching the mid-section of the cylinder?

Any help will be greatly appreciated! Many thanks!
Victor

[Andrea1984]

Hi Victor,

are you trying to simulate a counterflow flame here? If yes make sure that the strain rate is not too high otherwise the flame will be estinguished. It would probably be easier to simulate a simple swirl or bluff-body burner in order for the flame to be stable.

If your case is turbulent I would recommend you to follow the following steps (I am assuming that you are using the species transport model):
- run a cold flow simulation
- patch high temperature and product species within the domain (close to where you expect the flame to be ignited)
-select the Eddy Dissipation model and solve it (the combustion should be ignited now)
-switch to Finite Rate/Eddy Dissipation model if necessary

Hope this is helpful
Andrea

[maziar77]

Originally Posted by Andrea1984

Hi Victor,

are you trying to simulate a counterflow flame here? If yes make sure that the strain rate is not too high otherwise the flame will be estinguished. It would probably be easier to simulate a simple swirl or bluff-body burner in order for the flame to be stable.

If your case is turbulent I would recommend you to follow the following steps (I am assuming that you are using the species transport model):
- run a cold flow simulation
- patch high temperature and product species within the domain (close to where you expect the flame to be ignited)
-select the Eddy Dissipation model and solve it (the combustion should be ignited now)
-switch to Finite Rate/Eddy Dissipation model if necessary

Hope this is helpful
Andrea

I have similar problem. i use species transport model with detailed GRI mechanism but I get no combustion with eddy dissipation model. i also patch temperature and products.