FDS info and benchmark

[catetrib]

Dear all,

I'm an italian engineer, working in CFD field, approaching the study
of fire simulation.

I would like to ask you if FDS is able to reproduce the
flame propagation in space, and expecially if it is able to
predict the starting instant of the combustion of different
materials inside a domain where fire is still burning.

Also, I would like to ask you if it is possible to receive
material, like articoles, data, etc.., of a benchmark test,
in order to try to reproduce it on my own.

Thanks for your time and attention,

Caterina

[Kevin]

I do not understand the phrase "... able to reproduce the flame
propagation in space, ..." Can you give a specific example.

Also, in the next few weeks, we plan to release a separate guide for
FDS validation, which will include experimental data.

[Caterina Tribuzi]

> I do not understand the phrase "... able to reproduce the flame
> propagation in space, ..."  Can you give a specific example.

For example, something is burning inside a room, where inflammable furniture, e.g. a chair, is present. At first the chair is not reached by the fire but then, after the flame propagation and growth, and maybe also thanks to the high temperature reached, the chair starts to burn.
Is it possible to simulate this using FDS?

Thanks,

Caterina

2008/7/1 Kevin <mcgr...@gmail.com>:

[Jianping]

Yes, FDS does this! As a matter of fact, this is what FDS is for.

However, modeling pyrolysis of solids is highly complex because in
general not all the information concerning the material (needed in the
pyrolysis model) is available, let alone fire spread. So be cautious
when interpreting your results.

On Jul 2, 10:48 am, "Caterina Tribuzi" <catet...@gmail.com> wrote:
> > I do not understand the phrase "... able to reproduce the flame
> > propagation in space, ..." Can you give a specific example.
>
> For example, something is burning inside a room, where inflammable
> furniture, e.g. a chair, is present. At first the chair is not reached by
> the fire but then, after the flame propagation and growth, and maybe also
> thanks to the high temperature reached, the chair starts to burn.
> Is it possible to simulate this using FDS?
>
> Thanks,
>
> Caterina
>

> 2008/7/1 Kevin <mcgra...@gmail.com>:

[Apollo]

Can I know how did you arrive at this conclusion please?

AFAIK, there is a pertinent issue of low or zero gravity which leads
to a large uncertainty about fire behavior.

NASA does publish some papers on this area of research

And I quote

The impact of microgravity on fire behavior is substantial. Fires
generate large density gradients, whichproduce upward buoyant flows
under the influence of terrestrial gravity. In microgravity, buoyant
forces andflows are reduced or eliminated, greatly modifying heat and
mass transport rates and, in turn, fire charac-teristics and control.
The consequence may be either an increase or decrease in fire
initiation and spread,depending on the particular scenario. Thus, the
relationship of microgravity fire hazards to those in normalgravity
is, in general, difficult to assess (Ross, 1996).

http://gltrs.grc.nasa.gov/reports/1998/TM-1998-207417.pdf.

[Kevin]

Questions are often asked of us that start with the phrase "Does FDS
do ..." As Jianping says, the answer is often "Yes, but ..." There
are some fire scenarios where the fire's HRR is specified, and FDS
computes the transport of smoke and heat throughout the compartment or
building. These calculations are relatively easy to set up, and with
appropriate grid resolution, predict the various quantities of
interest to within about 20% of experimental measurements (US NRC,
NUREG-1824). However, for fire scenarios involving flame spread,
second item ignition, and so on, there are many other issues to
consider. The numerical algorithms in FDS do allow for these
phenomena, but there is more uncertainty in the model inputs, and
error associated with the model assumptions, than those of the smoke
and heat transport application.

How well FDS predicts a particular physical quantity is the subject of
past, present and future validation work. With the upcoming release of
FDS 5.2, we will release the most recent examples of FDS validation.
As we continue to improve the model, we will continue to add new
applications to this guide so that hopefully in the future we can cite
specific examples of FDS performance, and quantify FDS error, in a
more systematic way.