Hello Fluent user's ,

I have a question for everybody! I'm working on a combustion simulation in a 3D furnace. My problem is that I have 3 streams: -Air i + fuel -Air ii -Air iii

Each stream is introduced by different canals; When I introduce the data into the PDF table, I'd like to change the ratio of oxygen and nitrogen of the "Air i" but I think I cannot because if I change the ratio of the oxidizer, the ratio of the 3 airs will be changed.

I'd like to know your opinion on this and any help on it will be really appreciated.

Kind regards,

In the non premixed combustion model you can use the most 3 different streams. I imagine that you use only one stream for the fuel. So the first stream in your case must be for the coal, and 2 streams will be available. Therefore you can define two oxidiser streams with different N2/O2 ratio. One of these shall correspond to Air ii and Air iii (same composition) and the other to Air i (altered composition).

If you want to define 2 streams for the coal (volatiles stream and char stream), you can define only 1 stream for the oxidiser, so the N2/O2 ratio will be the same for all air inlets.

I hope that I helped you.

Good luck,

Ilias

thank you very much Ilias,

i'd like to know what i have to do to define two oxidizer stremas in prePDF

if anybody could explain me...

First of all you should enable the secondary stream. This stream could be anything (secondary fuel, secondary oxidiser, inert gas etc.) Then you must define the composition of the secondary (oxidiser) stream (as you did for the main oxidiser stream)

I advice you to study carefully chapter 14 of the user guide (page 14/40--> title--> Define the Fuel and Oxidizer (and Secondary-Stream)Compositions)

Good luck,

Ilias