Download - Experimental study of the concentration build-up regimes in an enclosure without ventilation
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ICHS 4, San Francisco, California, USA, September 2011
Experimental study of the Experimental study of the concentration build-up regimes in concentration build-up regimes in an enclosure without ventilationan enclosure without ventilation
B.CARITEAU, I. TKATSCHENKOCEA Saclay, DEN, DM2S, SMFE, LEEF
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ICHS 4, San Francisco, California, USA, September 2011
U0,
V
X(z)?
Dispersion in an enclosure without ventilation
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ICHS 4, San Francisco, California, USA, September 2011
A wide range of injection velocity
U0,
V
X(z)?
Dispersion in an enclosure without ventilation
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ICHS 4, San Francisco, California, USA, September 2011
A wide range of injection velocity
U0,
V
X(z)?
U0Buoyancy dominated dispersion
Momentum dominated dispersion
Dispersion in an enclosure without ventilation
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ICHS 4, San Francisco, California, USA, September 2011
Volume Richardson number:
U0Buoyancy dominated dispersion
Momentum dominated dispersion
Cleaver et. al. (1994, J. Hazardous Mater. Vol. 36) 200
031
UVgRi a
v
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ICHS 4, San Francisco, California, USA, September 2011
Volume Richardson number:
RivBuoyancy dominated dispersion
Momentum dominated dispersion
Cleaver et. al. (1994, J. Hazardous Mater. Vol. 36) 200
031
UVgRi a
v
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ICHS 4, San Francisco, California, USA, September 2011
Volume Richardson number:
RivBuoyancy dominated dispersion
Momentum dominated dispersion
Cleaver et. al. (1994, J. Hazardous Mater. Vol. 36)
1
200
031
UVgRi a
v
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ICHS 4, San Francisco, California, USA, September 2011
Volume Richardson number:
RivBuoyancy dominated dispersion
Momentum dominated dispersion
Cleaver et. al. (1994, J. Hazardous Mater. Vol. 36)
1
Stratified
0
0,2
0,4
0,6
0,8
1
0 10 20
z/H
X/X*
t Worster & Huppert (1984, J. Fluid. Mech. Vol. 132)
time
200
031
UVgRi a
v
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ICHS 4, San Francisco, California, USA, September 2011
Volume Richardson number:
RivBuoyancy dominated dispersion
Momentum dominated dispersion
Cleaver et. al. (1994, J. Hazardous Mater. Vol. 36)
1
Stratified
0
0,2
0,4
0,6
0,8
1
0 10 20
z/H
X/X*
t Worster & Huppert (1984, J. Fluid. Mech. Vol. 132)
time21
0
vRiRd
dH
Homogeneous layer
200
031
UVgRi a
v
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ICHS 4, San Francisco, California, USA, September 2011
Volume Richardson number:
RivBuoyancy dominated dispersion
Momentum dominated dispersion
200
031
UVgRi a
v
Cleaver et. al. (1994, J. Hazardous Mater. Vol. 36)
1
Stratified
0
0,2
0,4
0,6
0,8
1
0 10 20
z/H
X/X*
t Worster & Huppert (1984, J. Fluid. Mech. Vol. 132)
RiVc
time21
0
vRiRd
dH
Homogeneous layer
Fully homogeneous
Hd
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ICHS 4, San Francisco, California, USA, September 2011
Goals of the present experiments:
RivBuoyancy dominated dispersion
Momentum dominated dispersion
1
Stratified
0
0,2
0,4
0,6
0,8
1
0 10 20
z/H
X/X*
t Worster & Huppert (1984, J. Fluid. Mech. Vol. 132)
RiVc
time21
0
vRiRd
dH
Homogeneous layer
Fully homogeneous
Hd
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ICHS 4, San Francisco, California, USA, September 2011
Momentum dominated dispersion
Buoyancy dominated dispersion
0
0,2
0,4
0,6
0,8
1
0 10 20
z/H
X/X*
t Worster & Huppert (1984, J. Fluid. Mech. Vol. 132)
RiVc
time21
0
vRiRd
Hd
Riv
1
Goals of the present experiments:
Stratified
dH
Homogeneous layer
Fully homogeneous
Check the existence of these regimes
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ICHS 4, San Francisco, California, USA, September 2011
Momentum dominated dispersion
RivBuoyancy dominated dispersion
1 RiVc
Hd
Stratified
dH
Homogeneous layer
Fully homogeneous
0
0,2
0,4
0,6
0,8
1
0 10 20
z/H
X/X*
t Worster & Huppert (1984, J. Fluid. Mech. Vol. 132)
time21
0
vRiRd
Goals of the present experiments:
Check the validity of existing models
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ICHS 4, San Francisco, California, USA, September 2011
21
0
vRiRd
time
Buoyancy dominated dispersion
Stratified
dH
Homogeneous layer
0
0,2
0,4
0,6
0,8
1
0 10 20
z/H
X/X*
t Worster & Huppert (1984, J. Fluid. Mech. Vol. 132)
Momentum dominated dispersion
Riv
1 RiVc
Hd
Fully homogeneous
Goals of the present experiments:
Give a criterion for fully homogenous regime
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15ICHS 4, San Francisco, California, USA, September 2011
Experimental set-upExperimental set-up
Dispersion for RiDispersion for Rivv>1 : >1 : Buoyancy dominated regimeBuoyancy dominated regime
Dispersion for RiDispersion for Rivv<1 : <1 : Homogeneous layer formationHomogeneous layer formation
Dispersion for RiDispersion for Rivv<<1 : <<1 : Criterion for fully homogeneous Criterion for fully homogeneous
dispersion dispersion
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16ICHS 4, San Francisco, California, USA, September 2011
Experimental set-upExperimental set-up
Dispersion for RiDispersion for Rivv>1 : >1 : Buoyancy dominated regimeBuoyancy dominated regime
Dispersion for RiDispersion for Rivv<1 : <1 : Homogeneous layer formationHomogeneous layer formation
Dispersion for RiDispersion for Rivv<<1 : <<1 : Criterion for fully homogeneous Criterion for fully homogeneous
dispersion dispersion
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ICHS 4, San Francisco, California, USA, September 2011
Experimental setup and injection Experimental setup and injection conditionsconditions
Working gases : Helium and Air
Injection tube
930m
m
930mm
1260
mm
Top view
Side view
10mm hole
V=1,1m3
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ICHS 4, San Francisco, California, USA, September 2011
Experimental setup and injection Experimental setup and injection conditionsconditions
Source :
D0=5mm or 20mmX0=60%, 80% or 100% heliumQ0=1 to 350Nl/min
Working gases : Helium and Air
Injection tube
930m
m
930mm
1260
mm
Top view
Side view
10mm hole
V=1,1m3
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ICHS 4, San Francisco, California, USA, September 2011
Experimental setup and injection Experimental setup and injection conditionsconditions
Source :
D0=5mm or 20mmX0=60%, 80% or 100% heliumQ0=1 to 350Nl/min
Ri0=5.6 10-6 to 200Riv=2.3 10-3 to 20000
20
0
0
00 U
RgRi a
Injection tube
930m
m
930mm
1260
mm
Top view
Side view
10mm hole
V=1,1m3
Working gases : Helium and Air
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ICHS 4, San Francisco, California, USA, September 2011
Experimental setup and injection Experimental setup and injection conditionsconditions
Injection tube
930m
m
930mm
1260
mm
Top view
Side view
10mm hole
V=1,1m3
Local helium volume fraction measurement : Mini-Katharometers
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ICHS 4, San Francisco, California, USA, September 2011
Experimental setup and injection Experimental setup and injection conditionsconditions
Injection tube
930m
m
930mm
1260
mm
Top view
Side view
10mm hole
V=1,1m3
Heat conductivity measurement
7mm
Local helium volume fraction measurement : Mini-Katharometers
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ICHS 4, San Francisco, California, USA, September 2011
Experimental setup and injection Experimental setup and injection conditionsconditions
100mm
220mm
340mm
460mm
580mm
700mm
820mm
940mm
1060mm
1140mm
Injection tube
mini-katharometers
300mm
580mm
180m
m35
0mm
930m
m
930mm
1260
mm
Top view
Side view
10mm hole
V=1,1m3
Heat conductivity measurement
7mm
Local helium volume fraction measurement : Mini-Katharometers
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23ICHS 4, San Francisco, California, USA, September 2011
Experimental set-upExperimental set-up
Dispersion for RiDispersion for Rivv>1 : >1 : Buoyancy dominated regimeBuoyancy dominated regime
Dispersion for RiDispersion for Rivv<1 : <1 : Homogeneous layer formationHomogeneous layer formation
Dispersion for RiDispersion for Rivv<<1 : <<1 : Criterion for fully homogeneous Criterion for fully homogeneous
dispersion dispersion
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ICHS 4, San Francisco, California, USA, September 2011
0
0,2
0,4
0,6
0,8
1
0 5 10 15 20 25 30
X/X*
z/H
5t*10t*20t*
Source : D=20mm, Riv=3 to 20000
Comparison with Worster & Huppert (1983) model.
Dispersion for RiDispersion for Rivv>1 : Buoyancy dominated regime>1 : Buoyancy dominated regime
Volume fraction vs height and time
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ICHS 4, San Francisco, California, USA, September 2011
0
0,2
0,4
0,6
0,8
1
0 5 10 15 20 25 30
X/X*
z/H
5t*10t*20t*
Source : D=20mm, Riv=3 to 20000
Comparison with Worster & Huppert (1983) model.
31
32
34
32
0
*
4 BHAt
0
0*35
34
32
32
4 gHBX
Characteristic time and volume fraction:
Dispersion for RiDispersion for Rivv>1 : Buoyancy dominated regime>1 : Buoyancy dominated regime
Volume fraction vs height and time
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ICHS 4, San Francisco, California, USA, September 2011
0
0,2
0,4
0,6
0,8
1
0 5 10 15 20 25 30
X/X*
z/H
5t*10t*20t*
Source : D=20mm, Riv=3 to 20000
Comparison with Worster & Huppert (1983) model.
31
32
34
32
0
*
4 BHAt
0
0*35
34
32
32
4 gHBX
Characteristic time and volume fraction:
Dispersion for RiDispersion for Rivv>1 : Buoyancy dominated regime>1 : Buoyancy dominated regime
Volume fraction vs height and time
The entrainement coefficient
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ICHS 4, San Francisco, California, USA, September 2011
0
0,2
0,4
0,6
0,8
1
0 5 10 15 20 25 30
X/X*
z/H
5t*10t*20t*
Source : D=20mm, Riv=3 to 20000
Comparison with Worster & Huppert (1983) model.
31
32
34
32
0
*
4 BHAt
0
0*35
34
32
32
4 gHBX
Characteristic time and volume fraction:
Dispersion for RiDispersion for Rivv>1 : Buoyancy dominated regime>1 : Buoyancy dominated regime
Volume fraction vs height and time
The entrainement coefficient
Tuned between 0.065 and 0.04
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ICHS 4, San Francisco, California, USA, September 2011
0
0,2
0,4
0,6
0,8
1
0 5 10 15 20 25 30
X/X*
z/H
5t*10t*20t*
Source : D=20mm, Riv=3 to 20000
Comparison with Worster & Huppert (1983) model.
31
32
34
32
0
*
4 BHAt
0
0*35
34
32
32
4 gHBX
Characteristic time and volume fraction:
Dispersion for RiDispersion for Rivv>1 : Buoyancy dominated regime>1 : Buoyancy dominated regime
Volume fraction vs height and time
The entrainement coefficient
Tuned between 0.065 and 0.04
Source Ri0 from 0.03 to 200
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ICHS 4, San Francisco, California, USA, September 2011
Source : D=5mm, Riv=3 to 75
Dispersion for RiDispersion for Rivv>1 : Buoyancy dominated regime>1 : Buoyancy dominated regime
0
0,1
0,2
0,3
0,4
0,5
0,6
0,7
0,8
0,9
1
0 20 40 60 80
X/X*
z/H
Q=1Nl/minQ=2Nl/minQ=3Nl/minQ=4Nl/minQ=5Nl/min
t/t*=10 t/t*=20 t/t*=40Volume fraction vs height and time
Entrainement coefficient : 0.1
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ICHS 4, San Francisco, California, USA, September 2011
Worster et Huppert (1983) model
0
0,2
0,4
0,6
0,8
1
0 5 10 15 20 25
X/X*
z/H
t/t*=10t/t*=5 t/t*=20
Source : D=5mm, Riv=3 to 75
Dispersion for RiDispersion for Rivv>1 : Buoyancy dominated regime>1 : Buoyancy dominated regime
0
0,1
0,2
0,3
0,4
0,5
0,6
0,7
0,8
0,9
1
0 20 40 60 80
X/X*
z/H
Q=1Nl/minQ=2Nl/minQ=3Nl/minQ=4Nl/minQ=5Nl/min
t/t*=10 t/t*=20 t/t*=40Volume fraction vs height and time
Entrainement coefficient : 0.1
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31ICHS 4, San Francisco, California, USA, September 2011
Experimental set-upExperimental set-up
Dispersion for RiDispersion for Rivv>1 : >1 : Buoyancy dominated regimeBuoyancy dominated regime
Dispersion for RiDispersion for Rivv<1 : <1 : Homogeneous layer formationHomogeneous layer formation
Dispersion for RiDispersion for Rivv<<1 : <<1 : Criterion for fully homogeneous Criterion for fully homogeneous
dispersion dispersion
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ICHS 4, San Francisco, California, USA, September 2011
Vertical volume fraction profiles, D=5mm source
0,0
0,1
0,2
0,3
0,4
0,5
0,6
0,7
0,8
0,9
1,0
0,0 0,2 0,4 0,6 0,8 1,0 1,2 1,4 1,6 1,8 2,0X/<X>
z/H
Q=120Nl/minQ=100Nl/minQ=55Nl/minQ=7Nl/minQ=5Nl/min
At t=10, with QV100
Riv 0.00520.00750.0251.5 3
Dispersion for RiDispersion for Rivv<1 : Homogeneous layer formation<1 : Homogeneous layer formation
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ICHS 4, San Francisco, California, USA, September 2011
100
1000
0,001 0,01 0,1 1Riv
d/R
0
Xo=100%Xo=60%Xo=80%
Thickness of the homogeneous layer vs Riv
vRiRd 25
0
Dispersion for RiDispersion for Rivv<1 : Homogeneous layer formation<1 : Homogeneous layer formation
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34ICHS 4, San Francisco, California, USA, September 2011
Experimental set-upExperimental set-up
Dispersion for RiDispersion for Rivv>1 : >1 : Buoyancy dominated regimeBuoyancy dominated regime
Dispersion for RiDispersion for Rivv<1 : <1 : Homogeneous layer formationHomogeneous layer formation
Dispersion for RiDispersion for Rivv<<1 : <<1 : Criterion for fully homogeneous Criterion for fully homogeneous
dispersion dispersion
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ICHS 4, San Francisco, California, USA, September 2011
0
5
10
15
20
25
30
35
40
45
0 50 100 150 200
X (%
)
t (s)
0,1m0,22m0,34m0,46m0,58m0,70m0,82m0,94m1,06m1,14m
Local time variations of the volume fraction D=5mm, Riv=0.0023
Dispersion for RiDispersion for Rivv<<1 : <<1 : Criterion for fully homogeneous Criterion for fully homogeneous dispersion dispersion
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ICHS 4, San Francisco, California, USA, September 2011
Experimental critical values of Riv to reach
homogeneity
X0 (%) Riv100 0.002380 0.003560 0.0038
Critical value derived from the Cleaver et. al. (1994) correlation for the actual enclosure :
Riv = 0.0025
Dispersion for RiDispersion for Rivv<<1 : <<1 : Criterion for fully homogeneous Criterion for fully homogeneous dispersion dispersion
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ICHS 4, San Francisco, California, USA, September 2011
ConclusionsConclusions
The 3 regimes have been identified with respect to the The 3 regimes have been identified with respect to the volume Richardson numbervolume Richardson number Buoyancy dominated regime occurs for RiBuoyancy dominated regime occurs for Rivv>1>1 For RiFor Rivv>1, Worster & Huppert model fits fairly well with >1, Worster & Huppert model fits fairly well with the 20mm sourcethe 20mm source For RiFor Rivv>1, the 5mm source gives unexpected results with >1, the 5mm source gives unexpected results with much higher maximum volume fractionmuch higher maximum volume fraction For RiFor Rivv<1, formation of a homogeneous layer is observed, <1, formation of a homogeneous layer is observed, it sickness follows the Cleaver et. al. correlation only for it sickness follows the Cleaver et. al. correlation only for RiRivv<0.01<0.01 The Cleaver et. al. correlation can be extended to give a The Cleaver et. al. correlation can be extended to give a good critical value of the volume Richardson number below good critical value of the volume Richardson number below which the volume fraction is fully homogeneouswhich the volume fraction is fully homogeneous