Thunderhead Engineering Forum

Public Forum => PyroSim => Topic started by: Xoano on September 22, 2009, 09:39:10 am

Title: Scenario with a caracteristic fire load.
Post by: Xoano on September 22, 2009, 09:39:10 am
Hello,

I would simulate an scenario with a caracteristic fire load (MJ/m2) and the materials simulated into the scenario have a known heat release rate (kW/m2) or a mass loss rate (kg/m2┬Ěs). I tried 3 forms to solve this:

1) Place objects over all the surface of the scenario, for example cubes of 0,25x0,25x0,25 and introduce the thermal properties of this material (density, conductivity & specific heat)
Here I saw two ways to modelize this...

    1a) Govern the reaction by material: Introducing the pyrolisis reaction of the material. But it was difficult to obtain it...
    1b) Govern the reaction manually: Introducing the HRR or the mass loss rate, and ignition temperature.
         I prefered use this option, but in a large scenario the flame doesn't spread to the objects which are next to the initial burn vent and the objects over the burn. I don't know if that is consequence of not getting the needed temperature to begin the ignition of the objects near to the initial burn...

2) The other way I tried was place a vent on the total surface of the scenario, specifing the heat release rate according to a normal t-square curve customized in order to burn the total fire load (caracteristic fire load (MJ/m2) x area (m2)), and specifing the spread rate in the vent of the burner.

I compared the 2) option with zone models and they are similar... But I would solve the problems with my 1b) option...

What do you think about this?
Somebody could help me?
Thanks.

Xoano
Title: Re: Scenario with a caracteristic fire load.
Post by: Charlie Thornton on September 24, 2009, 07:38:47 am
Xoano,

Just to make sure I understand, the trouble you're having is that your burner vent doesn't seem to be igniting your flammable materials?  If you could post a model we might be able to identify the problem.

- Charlie