Material Property Data and FDS

["Kevin McGrattan" <kevin.mcgrattan@nist.gov>]

All

For some time now it has become painfully obvious that there is no
standardized way of obtaining all of the parameters you need to run FDS.
This is especially true of materials that burn.  There are various devices
that you can use to measure various properties, but there is no consensus on
the exact physical and mathematical description of these, and thus, no
standard way of taking benchscale data and converting it into an FDS input
file. If you search the FDS Discussion Group you will see many exchanges
that demonstrate the problem.

Our approach to solving this problem has two fundamental components. First,
we're trying to improve the description of the gas phase, mainly the fire
itself, to reduce the current level of grid sensitivity.  We cannot make
progress on the materials problem if we cannot be assured of a fairly
accurate, relatively grid-insensitive heat flux to the solid surface.
Second, we need to have a common understanding of the solid phase, both
mathematical and physical. Simo Hostikka wrote a fairly general description
of multi-layered, multi-component, multi-reaction solids into FDS 5, but now
where do we get all those parameters? Improved physics means more
experimental measurements. How do we get them?

The Building and Fire Research Lab at NIST has a small grants program, and
recently Nick Dempsey of WPI, Marc Janssens of Southwest Research, and
Morgan Hurley of the SFPE were awarded a three year grant to develop an
engineering guide that will document the standard test methods used to
obtain material properties, and more importantly the physical and
mathematical interpretation of these methods that will enable us all to
understand what to do with measurements made in the various benchscale
devices. As the project starts, more information will become available about
it.  For now, I'd like to remind you that at the upcoming IAFSS meeting in
Germany, Nick Dembsey and Simo Hostikka are hosting a workshop on Sunday,
September 21, to discuss the materials issue, and Nick can at that time
provide more information about the project. If you can make it, great. If
not, there will be opportunity, via our Discussion Group, to stay abreast of
progress.

Kevin

Kevin McGrattan
National Institute of Standards and Technology
100 Bureau Drive, Mail Stop 8663
Gaithersburg MD 20899
Phone: 301 975 2712
Fax:       301 975 4052