Smoke through the ducts

[Fabia Schirinzi]

Goodmorning,

I would like to simulate air ducts through which  the smoke passes in case of fire. These should be detached from the upper wall of the room, not internal to it. What material they are made of is not important. Looking at the simulation I did, it's like the smoke doesn't go through it and I don't understand the problem.

[...]

&OBST ID='Superior Wall", XB=0.0, 31, 0.0, 20 , 7.21, 9.41, SURF_ID='SupW'/

&HVAC TYPE_ID='DUCT', ID='duct1-2', NODE_ID='node-in 2','node 2.0', AREA=1.53, LOSS=1.,1., LENGTH=1.1/
&HVAC TYPE_ID='DUCT', ID='duct2-2', NODE_ID='node 2.0','node 2.1', AREA=1.53, LOSS=1.,1., LENGTH=5.5/
&HVAC TYPE_ID='DUCT', ID='duct3-2', NODE_ID='node 2.1','node 2.2', AREA=1.53, LOSS=1.,1., LENGTH=11.035/
&HVAC TYPE_ID='DUCT', ID='duct4-2', NODE_ID='node 2.2','node 2.3', AREA=1.53, LOSS=1.,1., LENGTH=5.1/
&HVAC TYPE_ID='DUCT', ID='duct5-2', NODE_ID='node 2.3','node-out 2', AREA=1.53, LOSS=1.,1., LENGTH=2.225/
&HVAC TYPE_ID='DUCT', ID='duct1-1', NODE_ID='node-in 1','node 1.0', AREA=1.53, LOSS=1.,1., LENGTH=1.1/
&HVAC TYPE_ID='DUCT', ID='duct2-1', NODE_ID='node 1.0','node 1.1', AREA=1.53, LOSS=1.,1.,  LENGTH=5.5/
&HVAC TYPE_ID='DUCT', ID='duct3-1', NODE_ID='node 1.1','node 1.2', AREA=1.53, LOSS=1.,1.,  LENGTH=9.775/
&HVAC TYPE_ID='DUCT', ID='duct4-1', NODE_ID='node 1.2','node 1.3', AREA=1.53, LOSS=1.,1.,  LENGTH=5.6/
&HVAC TYPE_ID='DUCT', ID='duct5-1', NODE_ID='node 1.3','node-out 1', AREA=1.53, LOSS=1.,1.,  LENGTH=2.225/
&HVAC TYPE_ID='DUCT', ID='duct A', NODE_ID='node-in A' node-out A', AREA=1.53, LOSS=1.,1.,LENGTH=2.40/

&VENT XB=9.725, 10.075, 4.965, 5.415, 5.61,5.61, ID='INLET2',SURF_ID='HVAC',COLOR='ORANGE', IOR=3/
&VENT XB=9.275,9.725,18.45,18.45,6.535,6.885, ID='OUTLET2',SURF_ID='HVAC',COLOR='GREEN', IOR=2/
&VENT XB=22.425, 22.775, 3.175, 3.625, 5.61,5.61, ID='INLET1',SURF_ID='HVAC',COLOR='ORANGE', IOR=3/
&VENT XB=22.275,22.725,15.4,15.4,6.535,6.885, ID='OUTLET1',SURF_ID='HVAC',COLOR='GREEN', IOR=2/
&VENT XB=12.325,12.675,21.1,21.55,7.86,7.86,ID='INLETA',SURF_ID='HVAC',COLOR='ORANGE',IOR=3/
&VENT XB=12.325,12.675,21.1,21.55,9.41,9.41, ID='OUTLETA',SURF_ID='HVAC',COLOR='GREEN', IOR=3/

&HVAC TYPE_ID='NODE', ID='node-in 2', DUCT_ID='duct1-2', VENT_ID='INLET2'/
&HVAC TYPE_ID='NODE', ID='node-out 2', DUCT_ID='duct5-2', VENT_ID='OUTLET2'/
&HVAC TYPE_ID='NODE', ID='node-in 1', DUCT_ID='duct1- 1', VENT_ID='INLET1'/
&HVAC TYPE_ID='NODE', ID='node-out 1', DUCT_ID='duct5-1', VENT_ID='OUTLET1'/
&HVAC TYPE_ID='NODE', ID='node-in acc', DUCT_ID='duct A', VENT_ID='INLETA/
&HVAC TYPE_ID='NODE', ID='node-out acc', DUCT_ID='duct A, VENT_ID='OUTLETA/

&HVAC TYPE_ID='NODE', ID='node 2.0', DUCT_ID='duct1-2','duct2-2',XYZ=9.9,5.19,6.71 /
&HVAC TYPE_ID='NODE', ID='node 2.1', DUCT_ID='duct2-2','duct3-2',XYZ=4.4,5.19,6.71 /
&HVAC TYPE_ID='NODE', ID='node 2.2', DUCT_ID='duct3-2','duct4-2',XYZ=4.4,16.225,6.71/
&HVAC TYPE_ID='NODE', ID='node 2.3', DUCT_ID='duct4-2','duct5-2',XYZ=9.5,16.225,6.71/
&HVAC TYPE_ID='NODE', ID='node 1.0', DUCT_ID='duct1-1','duct2-1',XYZ=22.6,3.4, 6.71  /
&HVAC TYPE_ID='NODE', ID='node 1.1', DUCT_ID='duct2-1','duct3-1',XYZ=28.1,3.4,6.71/
&HVAC TYPE_ID='NODE', ID='node 1.2', DUCT_ID='duct3-1','duct4-1',XYZ=28.1,13.175,6.71/
&HVAC TYPE_ID='NODE', ID='node 1.3', DUCT_ID='duct4-1','duct5-1',XYZ=22.5,13.175,6.71/

[...]

Thanks in advance

[dr_jfloyd]

How are you judging if anything is moving in the ducts? I don't see any DEVC output for mass flow/velocity and smooke mass fraction in the ducts in the snippet of input fie you provided. 

[joseragonfid]

Using this thread about smoke and ducts, I have a problem with this fact.

I have made a smoke extraction from an interior VENT, with his NODE, until another exterior VENT, for extracting smoke from inside the room.

This route is made up of three DUCTs. In DUCTs, I have placed a Device of Mass Fraction of Soot.

The problem is that the three Devices mark the same result at the same time when that is not possible.

Therefore, if I made a DUCT with a length of 10 meters, the smoke will show the same that if this length would be about 50 meters.

I don't know how to make it so that if I make the duct longer, the smoke takes longer to come out the other side.

Thanks!

[dr_jfloyd]

Read the discussion of the HVAC solver in the FDS Technical Reference Guide and in the User's Guide. By default there is no mass storage in the system. There is an option to enable this.