Learning Forum

[Diri Li]

I want to simulate an explosion reaction in a confined space by patching  a high temperature region to ignite the fire, why does the flame not propagate even though the temperature rises? Only the patched area reacts, why is that?

Any help is appreciated!

[Rob]

Without seeing images it's difficult to comment. What is the composition of the domain? 

[Diri Li]

The turbulence model I use is the standard k-e model, the combustion model is a finite rate/vortex dissipation model, the mixture is methane-air, the ignition temperature is set to 1800k, and I use SIMPLE's solution method.

[Diri Li]

A time step of 0.001s and a grid size of 0.5mm were set up

[Rob]

It looks to be getting warmer, where is the fuel coming from?

[Diri Li]

 the mass fraction of ch4 in the calculated domain was patched to 0.051

[Rob]

Should that producse deflagration given the chemistry model(s) used? 

[Diri Li]

Does that mean my combustion model doesn't burn and explode? I've seen simulations of this, but no matter how I set it up, I can't get the same effect. What changes should I make if I want my model to explode in this way?

[Rob]

What chemistry have you got set up? 

[Diri Li]

I used the built-in reaction in fluent: ch4＋2o2＝co2＋2h2o.

[Rob]

Please post an image of the species volume fractions. 

[Diri Li]

just like this:

thanks for your any hlep!

[Rob]

It should propagate. If you display the mesh, and show all walls what have you got?