ICHS 4, San Francisco, California, USA, September 2011 Experimental study of the concentration build-up regimes in an enclosure without ventilation B.CARITEAU, I. TKATSCHENKO CEA Saclay, DEN, DM2S, SMFE, LEEF

ICHS 4, San Francisco, California, USA, September 2011 U 0,   V X(z)? Dispersion in an enclosure without ventilation

ICHS 4, San Francisco, California, USA, September 2011 A wide range of injection velocity U 0,   V X(z)? Dispersion in an enclosure without ventilation

ICHS 4, San Francisco, California, USA, September 2011 A wide range of injection velocity U 0,   V X(z)? U0U0 Buoyancy dominated dispersion Momentum dominated dispersion Dispersion in an enclosure without ventilation

ICHS 4, San Francisco, California, USA, September 2011 Volume Richardson number: U0U0 Buoyancy dominated dispersion Momentum dominated dispersion Cleaver et. al. (1994, J. Hazardous Mater. Vol. 36)

ICHS 4, San Francisco, California, USA, September 2011 Volume Richardson number: Ri v Buoyancy dominated dispersion Momentum dominated dispersion Cleaver et. al. (1994, J. Hazardous Mater. Vol. 36)

ICHS 4, San Francisco, California, USA, September 2011 Volume Richardson number: Ri v Buoyancy dominated dispersion Momentum dominated dispersion Cleaver et. al. (1994, J. Hazardous Mater. Vol. 36) 1

ICHS 4, San Francisco, California, USA, September 2011 Volume Richardson number: Ri v Buoyancy dominated dispersion Momentum dominated dispersion Cleaver et. al. (1994, J. Hazardous Mater. Vol. 36) 1 Stratified Worster & Huppert (1984, J. Fluid. Mech. Vol. 132) time

ICHS 4, San Francisco, California, USA, September 2011 Volume Richardson number: Ri v Buoyancy dominated dispersion Momentum dominated dispersion Cleaver et. al. (1994, J. Hazardous Mater. Vol. 36) 1 Stratified Worster & Huppert (1984, J. Fluid. Mech. Vol. 132) time d H Homogeneous layer

ICHS 4, San Francisco, California, USA, September 2011 Volume Richardson number: Ri v Buoyancy dominated dispersion Momentum dominated dispersion Cleaver et. al. (1994, J. Hazardous Mater. Vol. 36) 1 Stratified Worster & Huppert (1984, J. Fluid. Mech. Vol. 132) Ri Vc time d H Homogeneous layerFully homogeneous

ICHS 4, San Francisco, California, USA, September 2011 Goals of the present experiments: Ri v Buoyancy dominated dispersion Momentum dominated dispersion 1 Stratified Worster & Huppert (1984, J. Fluid. Mech. Vol. 132) Ri Vc time d H Homogeneous layerFully homogeneous

ICHS 4, San Francisco, California, USA, September 2011 Momentum dominated dispersion Buoyancy dominated dispersion Worster & Huppert (1984, J. Fluid. Mech. Vol. 132) Ri Vc time Ri v 1 Goals of the present experiments: Stratified d H Homogeneous layerFully homogeneous Check the existence of these regimes

ICHS 4, San Francisco, California, USA, September 2011 Momentum dominated dispersion Ri v Buoyancy dominated dispersion 1 Ri Vc Stratified d H Homogeneous layerFully homogeneous Worster & Huppert (1984, J. Fluid. Mech. Vol. 132) time Goals of the present experiments: Check the validity of existing models

ICHS 4, San Francisco, California, USA, September 2011 time Buoyancy dominated dispersion Stratified d H Homogeneous layer Worster & Huppert (1984, J. Fluid. Mech. Vol. 132) Momentum dominated dispersion Ri v 1 Ri Vc Fully homogeneous Goals of the present experiments: Give a criterion for fully homogenous regime

15ICHS 4, San Francisco, California, USA, September 2011 Experimental set-up Dispersion for Ri v >1 : Buoyancy dominated regime Dispersion for Ri v <1 : Homogeneous layer formation Dispersion for Ri v <<1 : Criterion for fully homogeneous dispersion

16ICHS 4, San Francisco, California, USA, September 2011 Experimental set-up Dispersion for Ri v >1 : Buoyancy dominated regime Dispersion for Ri v <1 : Homogeneous layer formation Dispersion for Ri v <<1 : Criterion for fully homogeneous dispersion

ICHS 4, San Francisco, California, USA, September 2011 Experimental setup and injection conditions Working gases : Helium and Air Injection tube 930mm 1260mm Top view Side view 10mm hole V=1,1m 3

ICHS 4, San Francisco, California, USA, September 2011 Experimental setup and injection conditions Source : D 0 =5mm or 20mm X 0 =60%, 80% or 100% helium Q 0 =1 to 350Nl/min Working gases : Helium and Air Injection tube 930mm 1260mm Top view Side view 10mm hole V=1,1m 3

ICHS 4, San Francisco, California, USA, September 2011 Experimental setup and injection conditions Source : D 0 =5mm or 20mm X 0 =60%, 80% or 100% helium Q 0 =1 to 350Nl/min Ri 0 = to 200 Ri v = to Injection tube 930mm 1260mm Top view Side view 10mm hole V=1,1m 3 Working gases : Helium and Air

ICHS 4, San Francisco, California, USA, September 2011 Experimental setup and injection conditions Injection tube 930mm 1260mm Top view Side view 10mm hole V=1,1m 3 Local helium volume fraction measurement : Mini-Katharometers

ICHS 4, San Francisco, California, USA, September 2011 Experimental setup and injection conditions Injection tube 930mm 1260mm Top view Side view 10mm hole V=1,1m 3 Heat conductivity measurement 7mm Local helium volume fraction measurement : Mini-Katharometers

ICHS 4, San Francisco, California, USA, September 2011 Experimental setup and injection conditions 100mm 220mm 340mm 460mm 580mm 700mm 820mm 940mm 1060mm 1140mm Injection tube mini-katharometers 300mm 580mm 180mm 350mm 930mm 1260mm Top view Side view 10mm hole V=1,1m 3 Heat conductivity measurement 7mm Local helium volume fraction measurement : Mini-Katharometers

23ICHS 4, San Francisco, California, USA, September 2011 Experimental set-up Dispersion for Ri v >1 : Buoyancy dominated regime Dispersion for Ri v <1 : Homogeneous layer formation Dispersion for Ri v <<1 : Criterion for fully homogeneous dispersion

ICHS 4, San Francisco, California, USA, September 2011 Source : D=20mm, Ri v =3 to Comparison with Worster & Huppert (1983) model. Dispersion for Ri v >1 : Buoyancy dominated regime Volume fraction vs height and time

ICHS 4, San Francisco, California, USA, September 2011 Source : D=20mm, Ri v =3 to Comparison with Worster & Huppert (1983) model. Characteristic time and volume fraction: Dispersion for Ri v >1 : Buoyancy dominated regime Volume fraction vs height and time

ICHS 4, San Francisco, California, USA, September 2011 Source : D=20mm, Ri v =3 to Comparison with Worster & Huppert (1983) model. Characteristic time and volume fraction: Dispersion for Ri v >1 : Buoyancy dominated regime Volume fraction vs height and time The entrainement coefficient

ICHS 4, San Francisco, California, USA, September 2011 Source : D=20mm, Ri v =3 to Comparison with Worster & Huppert (1983) model. Characteristic time and volume fraction: Dispersion for Ri v >1 : Buoyancy dominated regime Volume fraction vs height and time The entrainement coefficient Tuned between and 0.04

ICHS 4, San Francisco, California, USA, September 2011 Source : D=20mm, Ri v =3 to Comparison with Worster & Huppert (1983) model. Characteristic time and volume fraction: Dispersion for Ri v >1 : Buoyancy dominated regime Volume fraction vs height and time The entrainement coefficient Tuned between and 0.04 Source Ri 0 from 0.03 to 200

ICHS 4, San Francisco, California, USA, September 2011 Source : D=5mm, Ri v =3 to 75 Dispersion for Ri v >1 : Buoyancy dominated regime Volume fraction vs height and time Entrainement coefficient : 0.1

ICHS 4, San Francisco, California, USA, September 2011 Worster et Huppert (1983) model Source : D=5mm, Ri v =3 to 75 Dispersion for Ri v >1 : Buoyancy dominated regime Volume fraction vs height and time Entrainement coefficient : 0.1

31ICHS 4, San Francisco, California, USA, September 2011 Experimental set-up Dispersion for Ri v >1 : Buoyancy dominated regime Dispersion for Ri v <1 : Homogeneous layer formation Dispersion for Ri v <<1 : Criterion for fully homogeneous dispersion

ICHS 4, San Francisco, California, USA, September 2011 Vertical volume fraction profiles, D=5mm source At t=10 , with Ri v Dispersion for Ri v <1 : Homogeneous layer formation

ICHS 4, San Francisco, California, USA, September 2011 Thickness of the homogeneous layer vs Ri v Dispersion for Ri v <1 : Homogeneous layer formation

34ICHS 4, San Francisco, California, USA, September 2011 Experimental set-up Dispersion for Ri v >1 : Buoyancy dominated regime Dispersion for Ri v <1 : Homogeneous layer formation Dispersion for Ri v <<1 : Criterion for fully homogeneous dispersion

ICHS 4, San Francisco, California, USA, September 2011 Local time variations of the volume fraction D=5mm, Ri v = Dispersion for Ri v <<1 : Criterion for fully homogeneous dispersion

ICHS 4, San Francisco, California, USA, September 2011 Experimental critical values of Ri v to reach homogeneity X 0 (%)Ri v Critical value derived from the Cleaver et. al. (1994) correlation for the actual enclosure : Ri v = Dispersion for Ri v <<1 : Criterion for fully homogeneous dispersion

ICHS 4, San Francisco, California, USA, September 2011 Conclusions The 3 regimes have been identified with respect to the volume Richardson number The 3 regimes have been identified with respect to the volume Richardson number Buoyancy dominated regime occurs for Ri v >1 Buoyancy dominated regime occurs for Ri v >1 For Ri v >1, Worster & Huppert model fits fairly well with the 20mm source For Ri v >1, Worster & Huppert model fits fairly well with the 20mm source For Ri v >1, the 5mm source gives unexpected results with much higher maximum volume fraction For Ri v >1, the 5mm source gives unexpected results with much higher maximum volume fraction For Ri v <1, formation of a homogeneous layer is observed, it sickness follows the Cleaver et. al. correlation only for Ri v <0.01 For Ri v <1, formation of a homogeneous layer is observed, it sickness follows the Cleaver et. al. correlation only for Ri v <0.01 The Cleaver et. al. correlation can be extended to give a good critical value of the volume Richardson number below which the volume fraction is fully homogeneous The Cleaver et. al. correlation can be extended to give a good critical value of the volume Richardson number below which the volume fraction is fully homogeneous