Sidewall sprinklers in PyroSim, reduction of heat flux

[oysteinsmalme]

Hi, my first post here :)

 

I'm doing a simulation on the effect sidewall sprinklers have on tempered glass vs fire resistant glass.

Danish Fire Engineers have done a real-size experiment on the same thing, and my goal is to replicate this and adjust the sprinkler coeffisient so that I match the Danish results. This will hopefully make simulation of sidewall sprinklers more accurate in later problems/simulations.

My question is:

Has anyone tried this before? Will sidewall sprinklers cool off heat flux on a window, or is this not possible to do in PyroSim/FDS?

Regards

Øystein S. Malme

[Jonna]

Welcome to the forum!

First; Several others will probaly also comment this, but Pyrosim is
only a graphical user interface to make it easier to write inputfiles
for FDS. In other words, everything you can do in Pyrosim, you can
also do by manually creating the inputfiles for FDS using for example
a simple texteditor like notepad :-) (recommended to get a good feel
for how the input-code in FDS works!) Pyrosim also have their own
supportforum at http://www.thunderheadeng.net/forum/index.php/board,1.0.html
where you can ask Pyrosim-specific questions to developers/other
users.

Second; About your problem, I would take a look at the examples that
come with FDS regarding sprinklers and sprays, perhaps more
spesifically water_cooling.fds. It sounds to me you are looking for
something like that!

Regards

Jonna

[oysteinsmalme]

Ok, thank you.

 

I've tried the PyroSim-forum, but it has been drowned in spam recently :)

I'll try out FDS-coding manually, and have a look at the examples! (found on NIST/fire?)

 

I'll probably ask again, and I'll post an update here if/when I've done the simulation.

 

Øystein

 

[Jonna]

The examples are also "installed" when you install FDS5. They are then
found in the folder where you installed FDS5, under the subfolder
"Examples" (and subfolder "Sprinkler and Sprays").

I do believe the examples are also installed when installing Pyrosim,
which might be your case. They should probaly then be located in your
Pyrosim folder, in the subfolder samples, and then FDS5.

Good luck with your project!

Regards

Jonna

[Bryan Klein]

Hello Øystein,

I wanted to cross post the response from Dec. 20th on the PyroSim Forum, in case you missed it.

In the FDS Technical Reference Guide, section 9.5.1 (Droplet Transport on a Surface) mentions the following:
"While attached to a surface, the 'droplet' is assumed to form a thin film of liquid that transfers heat to the solid, and heat and mass to the gas."
From that I gather that it should work, as long as your wall isn't a boundary condition (like a heater). But I've never made a model that uses that feature.

-Charlie Thornton

http://www.thunderheadeng.net/forum/index.php/topic,1102.0.html

We updated our forum software before the first of the year, and I think we have handled the spammers for now.  It seems that they are using humans in third world countries to post their junk now, determined people are much more difficult to stop than robots.

Best Regards,

-Bryan Klein

[oysteinsmalme]

Hi again

 

I tried to do a simulation with sprinklers, to see the effect they would have on cooling a wall.

I did a square room, 10x10meters, 5 meters in height. See att.file.

I put a large fire in the middle (how large is not important)

 

I did 3 sets of sprinklers,

- one side with only one sprinkler, 2.5 meters from the corner.

- one side with two sprinklers, 2.5 meters apart.

- one side with five sprinklers, 1 meter apart.

 

It seems that sprinklers cool off wall temperature, but "boost" heat flux (- see att.file.)? Could anyone confirm or explain this?

Am I doing it wrong?

 

Øystein

 

[Kevin]

Look at a case with no sprinklers. My guess is that what you are
seeing results from the fact that the radiation transport algorithm
distributes the radiation energy using a finite number (about 100) of
solid angles. This leads to a star-shaped flux pattern in the far
field.

>  Rad_vs_temp.jpg
> 96KViewDownload

[oysteinsmalme]

Thank you, I tried a case with no sprinklers, but I did'nt get the star-shaped pattern :(

I've attached an image of the results in rad.

 

Tricky this, but it's fancy to see the cooling-effect sprinklers have on wall temperature :)

 

Øystein

[Kevin]

Please post a simple input file to the Issue Tracker that demonstrates
the problem. I have to look at the case more carefully.

>  no_spr.jpg
> 41KViewDownload

[oysteinsmalme]

Done

But, I'm sorry, the file is witten i PyroSim. I'll learn to write input-files to FDS manually, I know... :)

[Bryan Klein]

PyroSim creates an FDS file that you can use to create the file Kevin is asking for.

Look for the .fds file in the place you identified after you clicked 'Run FDS...' in PyroSim.

Then, you can delete all of the lines that are unnecessary for demonstrating the behavior of interest.

-Bryan Klein

Thunderhead Eng.

[oysteinsmalme]

Yes, I found the "write FDS-file", but I'm not sure how much I can delete. I posted the entire file on the Issue Tracker, it was a fairly small file :)

Thanks for helping me out!

[oysteinsmalme]

Here is the Danish Report on sprinklers vs Fire-resistant glass.

Thought it would be helpful to see what I aim for :)