Can you recommend a validation report for calculating the fire HRR based on fire propagation and extinction model?

[yunlongjason]

Is there a validation report to calculating the fire HRR based on the input of surface HRR of a specific fuel (such a a pool fire) and its fire ignition and extinction parameters?

[yunlongjason]

While I am testing the sample case EXTINCTION_MODEL='EXTINCTION 1, I can not find any AIT spacified, but it did generated HRR.
I input a AIT=540, the result is the same, why?

&HEAD CHID='extinction_1', TITLE='Test_Case_For_Extinction_Models' /
&MISC GVEC(3) = -9.81, STRATIFICATION=.TRUE. /
&SURF ID= 'LINER', ADIABATIC=.TRUE., DEFAULT=.TRUE. /
&RADI RADIATION=.FALSE. /
&TIME T_END=1.25, DT=0.01, LOCK_TIME_STEP=.FALSE. /

&SPEC ID='NITROGEN', BACKGROUND=.TRUE./
&SPEC ID='METHANE' /
&SPEC ID='PROPANE' /
&SPEC ID='OXYGEN' /
&SPEC ID='WATER VAPOR' /
&SPEC ID='CARBON DIOXIDE' /

&REAC FUEL='METHANE'
RADIATIVE_FRACTION=0.0
AUTO_IGNITION_TEMPERATURE=540
SPEC_ID_NU='METHANE','OXYGEN','CARBON DIOXIDE','WATER VAPOR', NU=-1,-2,1,2 /

&REAC FUEL='PROPANE'
RADIATIVE_FRACTION=0.0
SPEC_ID_NU='PROPANE','OXYGEN','CARBON DIOXIDE','WATER VAPOR', NU=-1,-5,3,4 /

&COMB FIXED_MIX_TIME=0.0025, EXTINCTION_MODEL='EXTINCTION 1' /

&MESH IJK=4,4,4, XB=0.0,0.1,0.0,0.1,0.0,0.1 /
&INIT XB=0.0,0.1,0.0,0.1,0.0,0.1, SPEC_ID(1)='METHANE', MASS_FRACTION(1) = 0.0029, SPEC_ID(2)='OXYGEN', MASS_FRACTION(2)= 0.0115, TEMPERATURE = 26.85 /
&DEVC XB=0.0,0.1,0.0,0.1,0.0,0.1, QUANTITY='HRRPUV', SPATIAL_STATISTIC='VOLUME INTEGRAL', ID='HRR1' /
&DEVC XB=0.0,0.1,0.0,0.1,0.0,0.1, QUANTITY='TEMPERATURE', SPATIAL_STATISTIC='MEAN', ID='TEMP1' /
&DEVC XB=0.0,0.1,0.0,0.1,0.0,0.1, QUANTITY='MASS FRACTION', SPATIAL_STATISTIC='MEAN', SPEC_ID='OXYGEN', ID='O2_1' /
&DEVC XB=0.0,0.1,0.0,0.1,0.0,0.1, QUANTITY='MASS FRACTION', SPATIAL_STATISTIC='MEAN', SPEC_ID='METHANE', ID='METHANE_1' /

&MESH IJK=4,4,4, XB=0.2,0.3,0.0,0.1,0.0,0.1 /
&INIT XB=0.2,0.3,0.0,0.1,0.0,0.1, SPEC_ID(1)='METHANE', MASS_FRACTION(1) = 0.0029, SPEC_ID(2)='OXYGEN', MASS_FRACTION(2)= 0.0115, TEMPERATURE = 201.85 /
&DEVC XB=0.2,0.3,0.0,0.1,0.0,0.1, QUANTITY='HRRPUV', SPATIAL_STATISTIC='VOLUME INTEGRAL', ID='HRR2' /
&DEVC XB=0.2,0.3,0.0,0.1,0.0,0.1, QUANTITY='TEMPERATURE', SPATIAL_STATISTIC='MEAN', ID='TEMP2' /
&DEVC XB=0.2,0.3,0.0,0.1,0.0,0.1, QUANTITY='MASS FRACTION', SPATIAL_STATISTIC='MEAN', SPEC_ID='OXYGEN', ID='O2_2' /
&DEVC XB=0.2,0.3,0.0,0.1,0.0,0.1, QUANTITY='MASS FRACTION', SPATIAL_STATISTIC='MEAN', SPEC_ID='METHANE', ID='METHANE_2' /

.......

&MESH IJK=4,4,4, XB=1.8,1.9,0.0,0.1,1.8,1.9 /
&INIT XB=1.8,1.9,0.0,0.1,1.8,1.9, SPEC_ID(1)='METHANE', MASS_FRACTION(1) = 0.0546, SPEC_ID(2)='OXYGEN', MASS_FRACTION(2)= 0.2185, TEMPERATURE = 1601.85 /
&DEVC XB=1.8,1.9,0.0,0.1,1.8,1.9, QUANTITY='HRRPUV', SPATIAL_STATISTIC='VOLUME INTEGRAL', ID='HRR100' /
&DEVC XB=1.8,1.9,0.0,0.1,1.8,1.9, QUANTITY='TEMPERATURE', SPATIAL_STATISTIC='MEAN', ID='TEMP100' /
&DEVC XB=1.8,1.9,0.0,0.1,1.8,1.9, QUANTITY='MASS FRACTION', SPATIAL_STATISTIC='MEAN', SPEC_ID='OXYGEN', ID='O2_100' /
&DEVC XB=1.8,1.9,0.0,0.1,1.8,1.9, QUANTITY='MASS FRACTION', SPATIAL_STATISTIC='MEAN', SPEC_ID='METHANE', ID='METHANE_100' /

&TAIL /

[drjfloyd]

If you do not specify an AIT you use the default value as provided in the User's Guide.

Closely look at your results. There are a number of meshes in this case which have varying initial temperatures and mass fractions. You need to be looking at the devc file results which show the HRR per MESH rather than the hrr file which sums over all meshes. You should only be seeing HRR in those meshes where the temperature starts over 540 C and the Y_O2 meets the EXTINCTION 1 criteria.

[yunlongjason]

From the input file, I could not find any HRRPUV or HRRPUA, I don't know how is the total HRR obtained. Is this done internally based on the fuel of methane and oxygen concentration? I also didn't see any input regarding the pilot burner in this sample input file I provided above. Any comments?

[drjfloyd]

The extinction_1.fds has 100 DEVC outputs like this:

&DEVC XB=1.8,1.9,0.0,0.1,1.8,1.9, QUANTITY='HRRPUV', SPATIAL_STATISTIC='VOLUME INTEGRAL', ID='HRR100' /

The HRR is the result of the FDS combusition model. Please read the technical reference guide for details.

There is no pilot burner in exintction_1.fds. See the discussions of the FDS combustion model in the technical reference guide and the user's guide to understand how it works.

[yunlongjason]

From the technical reference guide, I can not find the HRR value that match the resulting HRR1 for example in the extinction_1.fds.
Can you guide me to the correct page? I also could not understand the criteria that resulted in the extinction of the fire. Is this based on Fig. 13.3 of the FDS User Guide?

[yunlongjason]

There is a definition list:
&SPEC ID='NITROGEN', BACKGROUND=.TRUE./
&SPEC ID='METHANE' /
&SPEC ID='OXYGEN' /
&SPEC ID='WATER VAPOR' /
&SPEC ID='CARBON DIOXIDE' /

Can I understand that the following will be true because of the above definitions?

SPEC_ID(0)='NITROGEN'
SPEC_ID(1)='METHANE'
SPEC_ID(2)='OXYGEN'
SPEC_ID(3)='WATER VAPOR'
SPEC_ID(4)='CARBON DIOXIDE'

MASS_FRACTION(1) = 0.0029 is for SPEC_ID(1)
MASS_FRACTION(2)= 0.0115 is for SPEC_ID(2)?

Thanks.

[drjfloyd]

No. Please read the User's Guide. There are many many examples of how to use species in the Guide.

[drjfloyd]

Why don't you create a simple test case and try it out?

[yunlongjason]

I tried with the sample file, it looks this INIT line defines SPEC_ID(x) and its initial MASS_FRECTION(x). But I still need to figure out how to verify the HRR from the volume where Oxygen and Methane coexist. I specified an AIT=540, it still ignites at a much higher temperature of 726 C for METHANE. I also can not find the reference alue of the HRR production.

[drjfloyd]

[yunlongjason]

Thanks Jason, May I give you a call via Teams? From the User Guide or Technical Guide, I can not find the information I wanted.

[drjfloyd]

If you have a specific question about something you do not understand in the guide post it here. Make sure your questions is specific and detailed enough that it is answerable without me just having to copy and paste sections of the documentation.

[yunlongjason]

There is a line under &REAC SPEC_ID_NU='METHANE','OXYGEN','CARBON DIOXIDE','WATER VAPOR', NU=-1,-2,1,2 /
Is this where the SPEC_ID(1) is defined to be "METHANE", and SPEC(2) is defined to be "OXYGEN"?

&MESH IJK=4,4,4, XB=0.0,0.1,0.0,0.1,0.0,0.1 /
&INIT XB=0.0,0.1,0.0,0.1,0.0,0.1, SPEC_ID(1)='METHANE', MASS_FRACTION(1) = 0.0029, SPEC_ID(2)='OXYGEN', MASS_FRACTION(2)= 0.0115, TEMPERATURE = 26.85 /