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Why does my transient simulations give the same results?

Question asked by Jonas Burman on Feb 15, 2014
Latest reply on Feb 20, 2014 by Jared Conway

Hello!

 

I've been trying to simulate a system for this past week and have been pulling my hair out for just as long.

 

What i'm trying to do is to simulate a burner, with gas exiting a diffuser into a burning chamber. What i want to see is how the flame will be affected by draging out some of the flue gases from the top of the chamber (a flame lying against the wall is no good). Since you can't simulate combustion in sw (or atleast it's hard), i'm faking it with hot air instead.

 

So to the problem. Every simulation i do practically gives the "flame" the same appearence every time: The flame points in a steep angle upwards, even if the flue gas exits straight out. Since the project is to see how the flame is affected by taking out some of the flue gases at the top of the burner no conclusions can be made if the flame is touching the wall even without the new exit. I've been trying to change temperatures flowrates etc with the same result. If the flame angel would differ randomly between every run it would be ok but even when i do a time dependent study the result is the same (FOR THE LOVE OF GOD WHY!?). I'm unsure how the solver works but i find it strange that my simulations of transient flow is so consistent.

 

You can see the result in the attached picture, unfortunately i can't show you the whole system but you can se the flow exiting the nozzle and exits straight out to the right.

 

Would be wery happy if anyone could explain why this is happening

 

/a Swede

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