[ArtSimulatingLife]

Hello, I (a student) am attempting to model a wood burning fire/stove. What I'd like to do is get to the point where I can measure the force of the gases (not pressure due to temperature, the force of the actual flow impact) on the glass on the front.

What I'm mainly interested in is if anyone has any advice/links to tutorials of fluid flow driven by burning wood (or other solid fuel). I have experience with CFX and so have reasonable knowledge of the software but have no idea how you would model the fire in order to generate the flow of the fluid around the inside of the chamber and up the chimney.

[ghorrocks]

You can model burning at many different levels.

At its simplest, you can model it as a heat source, so it just generates some heat which causes convection and/or radiation and generates air motions from that. This is easy and not much more complicated than the tutorial examples which come with CFX.

Then you can start modelling the fire at a basic level using fire models. These model the overall chemistry of the oxidation reaction and the key outputs of the reaction (water vapour, soot, CO2 etc) and are mainly empirical. This is significantly more complex and will take some work. There are some examples of flames in the CFX tutorial examples, but I don't think there is anything specifically on wood burning.

Then you can go for the full thing - burning wood is a complex chemical reaction involving many steps and hundreds of individual chemical reactions. Each chemical reaction has its own inputs and outputs and heat released. So you have to track dozens of chemical species and their reactions with each other. A model like this would be a PhD project in itself and take years to develop. It is not for inexperienced CFD people.

So you can model it at many different levels. I strongly suggest you start with the simple heat source approach (maybe with radiation as well if that is important) as for a CFD beginner there is plenty of things to learn even with that "simple" model.

[ArtSimulatingLife]

Originally Posted by ghorrocks

You can model burning at many different levels.

At its simplest, you can model it as a heat source, so it just generates some heat which causes convection and/or radiation and generates air motions from that. This is easy and not much more complicated than the tutorial examples which come with CFX.

Then you can start modelling the fire at a basic level using fire models. These model the overall chemistry of the oxidation reaction and the key outputs of the reaction (water vapour, soot, CO2 etc) and are mainly empirical. This is significantly more complex and will take some work. There are some examples of flames in the CFX tutorial examples, but I don't think there is anything specifically on wood burning.

Then you can go for the full thing - burning wood is a complex chemical reaction involving many steps and hundreds of individual chemical reactions. Each chemical reaction has its own inputs and outputs and heat released. So you have to track dozens of chemical species and their reactions with each other. A model like this would be a PhD project in itself and take years to develop. It is not for inexperienced CFD people.

So you can model it at many different levels. I strongly suggest you start with the simple heat source approach (maybe with radiation as well if that is important) as for a CFD beginner there is plenty of things to learn even with that "simple" model.

Thank you very much.

[cfdonline08]

Originally Posted by ghorrocks

You can model burning at many different levels.

At its simplest, you can model it as a heat source, so it just generates some heat which causes convection and/or radiation and generates air motions from that. This is easy and not much more complicated than the tutorial examples which come with CFX.

Then you can start modelling the fire at a basic level using fire models. These model the overall chemistry of the oxidation reaction and the key outputs of the reaction (water vapour, soot, CO2 etc) and are mainly empirical. This is significantly more complex and will take some work. There are some examples of flames in the CFX tutorial examples, but I don't think there is anything specifically on wood burning.

Then you can go for the full thing - burning wood is a complex chemical reaction involving many steps and hundreds of individual chemical reactions. Each chemical reaction has its own inputs and outputs and heat released. So you have to track dozens of chemical species and their reactions with each other. A model like this would be a PhD project in itself and take years to develop. It is not for inexperienced CFD people.

So you can model it at many different levels. I strongly suggest you start with the simple heat source approach (maybe with radiation as well if that is important) as for a CFD beginner there is plenty of things to learn even with that "simple" model.

Hi,

I am interested in modelling the fire occurs in a dumping box or similar to dumping box or storage boxes where the wood is used as dampers. My work is to find the behaviour of the wood burning when there is an accidental fire due to some reasons.

Could you explain in detail regarding the modelling of wood? For that I would to model a fire behaviour of wood.

I would like to get some inputs on how the approach should be and what are the factors I should consider? Also some general questions mentioned below,

How one should proceed? What are the necessary things to consider while modelling? Any tutorials available? How to specify the details while modelling combustion in terms of species concentration? Is it necessary to assume the volatiles the wood produces when burnt as an input for combustion modelling? Is it pre-mixed or non pre-mixed combustion? Is is necessary to consider soot?

Any help would be much appreciated.

[ghorrocks]

Your question is not suitable for a forum, it is far too broad.

You should have a look at the tutorials available, both on the ANSYS Customer webpage and online; read the documentation and read the literature on modelling this sort of thing.

[cfdonline08]

Originally Posted by ghorrocks

Your question is not suitable for a forum, it is far too broad.

You should have a look at the tutorials available, both on the ANSYS Customer webpage and online; read the documentation and read the literature on modelling this sort of thing.

I have tried to look into many literatures and ANSYS portal as well. But I did not find much information on wood fire modelling. Even in textbooks there is no mention in detail as I found some detailing in methane simulation in terms of the percentage of the species for the input etc.
I would be grateful if you share some experience if you any or mention some publications or any tutorials which mention these things.

[ghorrocks]

I have no experience in modelling solid fuel combustion.

My recommendation is as I said before: have a look at the tutorials available, both on the ANSYS Customer webpage and online; read the documentation and read the literature on modelling this sort of thing.

I suspect there won't be much on modelling solid fuel combustion in CFX, so the literature search is likely to be the important bit.

[Steffen595]

do you mean how the fire goes on from an ignition source to the surrounding material? Then you have to go on, wet or dry wood, how is is spread, radiation, the flame itself? Sounds trouble. I think there is different software for that, for fire spreading in buildings etc. For fire fighters, sprinkler layout, smoke development. Maybe you should look at that. Otherwise its way too complex, you may end up in a wild goose chase.
Kind of like my boss asking, can we model a boiler with hundreds of tubes? You have to work out when to say no.