Re: [fds-smv] fire consumption

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Dave McGill

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Mar 6, 2021, 9:05:36 AM3/6/21

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Hi,

The quick answer is that you can't combine a ramp with a spread rate. You can approximate the spread by having a series of burners, adjacent to each other, that come on at different times, and all shut down after 21 minutes.

On Sat, Mar 6, 2021 at 8:11 AM Mrtn Skc <mrt...@gmail.com> wrote:

Hi, I have a problem with my HRR.... i would like to shut it down after 21 min. Down below you can see how i implemented my code. I used the RAMP_Q. Unfortunately it is not working as expected. The HRR won't shut down. Is there any obvious mistake in my code?

#Title

&HEAD CHID='', TITLE='kleinehalle400qm' /
&MESH IJK=96.00, 96.00, 34.40, XB=00.00, 24.00, 00.00, 24.00, 00.00, 08.60, /

#Zeit und Umgebungsbedingungen

&TIME T_END=2400. /
&DUMP NFRAMES=2400. /



#Brennstoff

&REAC ID='FUEL', FUEL='REAC_FUEL', C=1.17, H=1.9, O=1, HEAT_OF_COMBUSTION=17280. /

#Geometrie

&OBST XB=01.70, 22.30, 01.70, 22.30, 00.00, 00.30, MATL_ID='CONCRETE', SURF_ID='CONCRETE WALL', TRANSPARENCY=0.75, COLOR='SILVER' / bottom
&OBST XB=01.70, 22.30, 01.70, 22.30, 06.30, 06.60, MATL_ID='CONCRETE', SURF_ID='CONCRETE WALL', TRANSPARENCY=0.75, COLOR='SILVER' / top
&OBST XB=01.70, 22.30, 01.70, 02.00, 00.30, 06.30, MATL_ID='CONCRETE', SURF_ID='CONCRETE WALL', TRANSPARENCY=0.75, COLOR='SILVER' / wall-south
&OBST XB=01.70, 02.00, 02.00, 22.00, 00.30, 06.30, MATL_ID='CONCRETE', SURF_ID='CONCRETE WALL', TRANSPARENCY=0.75, COLOR='SILVER' / wall-west
&OBST XB=22.00, 22.30, 02.00, 22.00, 00.30, 06.30, MATL_ID='CONCRETE', SURF_ID='CONCRETE WALL', TRANSPARENCY=0.75, COLOR='SILVER' / wall-east
&OBST XB=01.70, 22.30, 22.00, 22.30, 00.30, 06.30, MATL_ID='CONCRETE', SURF_ID='CONCRETE WALL', TRANSPARENCY=0.75, COLOR='SILVER' / wall-north

&HOLE XB=11.00, 13.00, 01.70, 02.00, 00.30, 02.80, / door
&HOLE XB=11.00, 13.00, 22.00, 22.30, 00.30, 02.80, / door
&HOLE XB=01.70, 02.00, 11.50, 12.50, 04.80, 05.80, / window
&HOLE XB=22.00, 22.30, 11.50, 12.50, 04.80, 05.80, / window

&VENT MB='XMIN', SURF_ID='OPEN' /
&VENT MB='XMAX', SURF_ID='OPEN' /
&VENT MB='YMIN', SURF_ID='OPEN' /
&VENT MB='YMAX', SURF_ID='OPEN' /
&VENT MB='ZMAX', SURF_ID='OPEN' /

#Materialeigenschaften

&SURF ID='CONCRETE WALL', HEAT_TRANSFER_COEFFICIENT=25. /

&MATL ID ='CONCRETE',
EMISSIVITY =0.9
DENSITY =2120.
SPECIFIC_HEAT_RAMP='c_ramp'
CONDUCTIVITY_RAMP ='k_ramp' /
&RAMP ID='c_ramp', T=20, F=0.9096 /
&RAMP ID='c_ramp', T=25, F=0.93235 /
&RAMP ID='c_ramp', T=30, F=0.9556 /
&RAMP ID='c_ramp', T=35, F=0.97935 /
&RAMP ID='c_ramp', T=40, F=1.0036 /
&RAMP ID='c_ramp', T=45, F=1.02835 /
&RAMP ID='c_ramp', T=50, F=1.0536 /
&RAMP ID='c_ramp', T=55, F=1.07935 /
&RAMP ID='c_ramp', T=60, F=1.1056 /
&RAMP ID='c_ramp', T=65, F=1.13235 /
&RAMP ID='c_ramp', T=70, F=1.1596 /
&RAMP ID='c_ramp', T=99, F=1.32751 /
&RAMP ID='c_ramp', T=100, F=2.422 /
&RAMP ID='c_ramp', T=139, F=2.3752 /
&RAMP ID='c_ramp', T=140, F=0.9432 /
&RAMP ID='c_ramp', T=199, F=1.086747 /
&RAMP ID='c_ramp', T=200, F=1.0768 /
&RAMP ID='c_ramp', T=524, F=1.327576 /
&RAMP ID='c_ramp', T=525, F=1.376 /
&RAMP ID='c_ramp', T=699, F=1.2368 /
&RAMP ID='c_ramp', T=700, F=1.22 /
&RAMP ID='c_ramp', T=1199, F=1.22 /

&RAMP ID='k_ramp', T= 20.0, F=1.747826 /
&RAMP ID='k_ramp', T= 99.0, F=1.75039824 /
&RAMP ID='k_ramp', T=100.0, F=1.7455 /
&RAMP ID='k_ramp', T=699.0, F=1.223172 /
&RAMP ID='k_ramp', T=700.0, F=1.23 /

#Brand

&SURF ID='fire', HRRPUA=144., COLOR='AQUAMARINE', RAMP_Q='fire_ramp' /
&VENT XB=02.00, 22.00, 02.00, 22.00, 00.30, 00.30, SURF_ID='fire', XYZ=12.00, 12.00, 00.30, SPREAD_RATE=0.01667 /

&RAMP ID='fire_ramp', T=0.0, F=0.0/
&RAMP ID='fire_ramp', T=0.1, F=1.0/
&RAMP ID='fire_ramp', T=1260, F=1.0/
&RAMP ID='fire_ramp', T=1261.0, F=0.0/

#Ergebnis-Ausgabe

&DEVC ID='T_AVERAGE', XB=02.00, 22.00, 02.00, 22.00, 06.00, 06.10, QUANTITY='TEMPERATURE', SPATIAL_STATISTIC='MEAN', /

&TAIL /

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Mrtn Skc

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Mar 6, 2021, 9:29:42 AM3/6/21

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but on the fds tutorial website there is a tutorial named radially spreading fire using a spread rate and a ramp ... the same in the user guide on page 96...so how does it work there?

Kevin McGrattan

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Mar 6, 2021, 9:32:04 AM3/6/21

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The RAMP controls an individual grid cell's burning rate. The cell ignites when the radial spreading fire passes over it. The RAMP would allow you to burn this cell for a specific amount of time before its fuel runs out. Your entire fire might last 20 min, but in any given spot, much less.

Mrtn Skc

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Mar 6, 2021, 9:48:30 AM3/6/21

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so just need to adjust the time on the ramp? not 21 min but figuering out what the time is from the last cell ingnited to end of 21 min in total

Kevin McGrattan

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Mar 6, 2021, 9:58:03 AM3/6/21

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The SPREAD_RATE determines how long the fire will last in total. The RAMP determines how long the fire will last at any given location.

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