August 5, 2019 at 8:32 pmriteshnwSubscriber
I want to do the simulation for flame propagation inside the railway tunnel.
I have drawn the geometry, but now I don't know how to proceed with meshing and other thing.
Please help me out.
This is my first time to deal with fire propagation inside the system.
Thank you in advance.
August 7, 2019 at 8:42 amDrAmineAnsys Employee
Do you want to model burn out propagation (propagation of products of combustion) or you want to include combustion in your analysis. If it is your first time I would rather make some training and tutorials.
August 7, 2019 at 3:39 pmriteshnwSubscriber
I am trying with some online tutorials.
I want to include combustion in my analysis for the emergency purpose in case of ventilation system in the tunnels.
August 8, 2019 at 4:56 amDrAmineAnsys EmployeeFlame propagation can be done with premixed model if reactants are mixed on entry into fluid domain.
August 14, 2019 at 9:04 amriteshnwSubscriber
Thank you Amine.
I will try with the premixed model.
There is also a big fan and there is sudden fire generation inside the tunnel.
What will you suggest me to see the fire propagation in presence of air from the fan? How can I proceed?
Till now I tried the simulations in fluid flow (Fluent) using k- epsilon model but I am not able to see any fire propagation.
August 14, 2019 at 9:07 amDrAmineAnsys Employee
Adding momentum flux to model the fan effect.
Without combustion model like premixed model you won't see any propagation.
August 14, 2019 at 9:12 amriteshnwSubscriber
I will tried adding non-premixed model but I couldn't see the result.
I will try once again with premixed model.
August 14, 2019 at 12:25 pmDrAmineAnsys Employee
It is not Lotto: you should not try all models. How is fuel and oxidizer feed into the tunnel. Fire can be modeled either as fire source by just adding heat into the volume or via combustion model. With combustion model it all depends how fuel and air are feed into the tunnel. For fire prorogation we usually use premixed model assuming all reactants are mixed on entrance and we want to track the flame propagation (discontinuity of burnt/unburnt components). Cheaper will be via Eddy Dissipation Model and assuming for fire efficiency and where the fuel source is added into air filled domain (in your case tunnel).
August 14, 2019 at 12:43 pmriteshnwSubscriber
In my case, it is an accidental fire at one selected location.
So it means I have to use premixed combustion. Correct?
August 14, 2019 at 12:56 pmDrAmineAnsys Employee
You can even use Eddy Breakup Model. Flame propagation with Premixed Model is expensive. Does it mean that in your case that the reacatants are mixed at that location and the fire starts?
Please have a look into this report on fire in tunnel using EBU: https://rib.msb.se/Filer/pdf/22988.pdf
August 14, 2019 at 1:00 pmriteshnwSubscriber
I will have a look and will try the simulation.
August 14, 2019 at 1:58 pmDrAmineAnsys Employee
August 22, 2019 at 8:14 amriteshnwSubscriber
I tried my model using premixed combustion model.
But, it shows the error as "floating point exception" when |I am trying transient simulation.
When I do steady simulation for 5000 iterations, the solution does not get converged.
I want to see the fire and smoke propagation inside the tunnel and when there is fire.
How can I model this?
I have fire source of 20 MW. the dimension of the fire source is 1 X 1 X 1 m3 located at the distance of 10 m from the fan of 2 m diameters in the tunnel section of 100 m long and 7 m width and height.
August 22, 2019 at 8:43 amDrAmineAnsys Employee
What about using what I have already suggested: Please have a look into this report on fire in tunnel using EBU: https://rib.msb.se/Filer/pdf/22988.pdf
As ANSYS Staff I cannot provide any other hints or look into your case.
August 22, 2019 at 9:17 amriteshnwSubscriber
I had a look in the report. But, I have not yet tried due to some technical problems.
I will try and will let you know.
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