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Experimental study of the concentration build-up regimes in an enclosure without ventilation

Experimental study of the concentration build-up regimes in an enclosure without ventilation. B.CARITEAU, I. TKATSCHENKO CEA Saclay, DEN, DM2S, SMFE, LEEF. Dispersion in an enclosure without ventilation. V. X(z)?. U 0 , Dr 0. Dispersion in an enclosure without ventilation. V. X(z)?.

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Experimental study of the concentration build-up regimes in an enclosure without ventilation

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  1. Experimental study of the concentration build-up regimes in an enclosure without ventilation B.CARITEAU, I. TKATSCHENKO CEA Saclay, DEN, DM2S, SMFE, LEEF

  2. Dispersion in an enclosure without ventilation V X(z)? U0, Dr0

  3. Dispersion in an enclosure without ventilation V X(z)? U0, Dr0 A wide range of injection velocity

  4. Dispersion in an enclosure without ventilation V X(z)? U0, Dr0 A wide range of injection velocity Buoyancy dominated dispersion Momentum dominated dispersion U0

  5. Volume Richardson number: Cleaver et. al. (1994, J. Hazardous Mater. Vol. 36) Buoyancy dominated dispersion Momentum dominated dispersion U0

  6. Volume Richardson number: Cleaver et. al. (1994, J. Hazardous Mater. Vol. 36) Buoyancy dominated dispersion Momentum dominated dispersion Riv

  7. Volume Richardson number: Cleaver et. al. (1994, J. Hazardous Mater. Vol. 36) Buoyancy dominated dispersion Momentum dominated dispersion Riv 1

  8. Volume Richardson number: Cleaver et. al. (1994, J. Hazardous Mater. Vol. 36) Buoyancy dominated dispersion Momentum dominated dispersion Riv 1 Stratified Worster & Huppert (1984, J. Fluid. Mech. Vol. 132) time

  9. Volume Richardson number: Cleaver et. al. (1994, J. Hazardous Mater. Vol. 36) Buoyancy dominated dispersion Momentum dominated dispersion Riv d 1 H Homogeneous layer Stratified Worster & Huppert (1984, J. Fluid. Mech. Vol. 132) time

  10. Volume Richardson number: Cleaver et. al. (1994, J. Hazardous Mater. Vol. 36) Buoyancy dominated dispersion Momentum dominated dispersion Riv d RiVc 1 H Homogeneous layer Fully homogeneous Stratified Worster & Huppert (1984, J. Fluid. Mech. Vol. 132) time

  11. Goals of the present experiments: Buoyancy dominated dispersion Momentum dominated dispersion Riv d RiVc 1 H Homogeneous layer Fully homogeneous Stratified Worster & Huppert (1984, J. Fluid. Mech. Vol. 132) time

  12. Goals of the present experiments: Check the existence of these regimes Buoyancy dominated dispersion Momentum dominated dispersion Riv d RiVc 1 H Homogeneous layer Fully homogeneous Stratified Worster & Huppert (1984, J. Fluid. Mech. Vol. 132) time

  13. Goals of the present experiments: Check the validity of existing models Buoyancy dominated dispersion Momentum dominated dispersion Riv d RiVc 1 H Homogeneous layer Fully homogeneous Stratified Worster & Huppert (1984, J. Fluid. Mech. Vol. 132) time

  14. Goals of the present experiments: Give a criterion for fully homogenous regime Buoyancy dominated dispersion Momentum dominated dispersion Riv d RiVc 1 H Homogeneous layer Fully homogeneous Stratified Worster & Huppert (1984, J. Fluid. Mech. Vol. 132) time

  15. Experimental set-up Dispersion for Riv>1 : Buoyancy dominated regime Dispersion for Riv<1 : Homogeneous layer formation Dispersion for Riv<<1 : Criterion for fully homogeneous dispersion

  16. Experimental set-up Dispersion for Riv>1 : Buoyancy dominated regime Dispersion for Riv<1 : Homogeneous layer formation Dispersion for Riv<<1 : Criterion for fully homogeneous dispersion

  17. Experimental setup and injection conditions Working gases : Helium and Air Side view Top view 1260mm 930mm 930mm 10mm hole Injection tube V=1,1m3

  18. Experimental setup and injection conditions Working gases : Helium and Air Side view Source : D0=5mm or 20mm X0=60%, 80% or 100% helium Q0=1 to 350Nl/min Top view 1260mm 930mm 930mm 10mm hole Injection tube V=1,1m3

  19. Experimental setup and injection conditions Working gases : Helium and Air Side view Source : D0=5mm or 20mm X0=60%, 80% or 100% helium Q0=1 to 350Nl/min Ri0=5.6 10-6 to 200 Riv=2.3 10-3 to 20000 Top view 1260mm 930mm 930mm 10mm hole Injection tube V=1,1m3

  20. Experimental setup and injection conditions Local helium volume fraction measurement : Mini-Katharometers Side view Top view 1260mm 930mm 930mm 10mm hole Injection tube V=1,1m3

  21. Experimental setup and injection conditions Local helium volume fraction measurement : Mini-Katharometers Heat conductivity measurement Side view Top view 1260mm 7mm 930mm 930mm 10mm hole Injection tube V=1,1m3

  22. Experimental setup and injection conditions Local helium volume fraction measurement : Mini-Katharometers 1140mm 1060mm Heat conductivity measurement Side view 940mm mini-katharometers 820mm Top view 700mm 350mm 580mm 1260mm 7mm 580mm 460mm 930mm 180mm 340mm 220mm 300mm 100mm 930mm 10mm hole Injection tube V=1,1m3

  23. Experimental set-up Dispersion for Riv>1 : Buoyancy dominated regime Dispersion for Riv<1 : Homogeneous layer formation Dispersion for Riv<<1 : Criterion for fully homogeneous dispersion

  24. Dispersion for Riv>1 : Buoyancy dominated regime Source : D=20mm, Riv=3 to 20000 Volume fraction vs height and time Comparison with Worster & Huppert (1983) model.

  25. Dispersion for Riv>1 : Buoyancy dominated regime Source : D=20mm, Riv=3 to 20000 Volume fraction vs height and time Comparison with Worster & Huppert (1983) model. Characteristic time and volume fraction:

  26. Dispersion for Riv>1 : Buoyancy dominated regime Source : D=20mm, Riv=3 to 20000 Volume fraction vs height and time Comparison with Worster & Huppert (1983) model. Characteristic time and volume fraction: The entrainement coefficient

  27. Dispersion for Riv>1 : Buoyancy dominated regime Source : D=20mm, Riv=3 to 20000 Volume fraction vs height and time Comparison with Worster & Huppert (1983) model. Characteristic time and volume fraction: The entrainement coefficient Tuned between 0.065 and 0.04

  28. Dispersion for Riv>1 : Buoyancy dominated regime Source : D=20mm, Riv=3 to 20000 Volume fraction vs height and time Comparison with Worster & Huppert (1983) model. Characteristic time and volume fraction: The entrainement coefficient Tuned between 0.065 and 0.04 Source Ri0 from 0.03 to 200

  29. Dispersion for Riv>1 : Buoyancy dominated regime Source : D=5mm, Riv=3 to 75 Volume fraction vs height and time Entrainement coefficient : 0.1

  30. Dispersion for Riv>1 : Buoyancy dominated regime Source : D=5mm, Riv=3 to 75 Worster et Huppert (1983) model Volume fraction vs height and time Entrainement coefficient : 0.1

  31. Experimental set-up Dispersion for Riv>1 : Buoyancy dominated regime Dispersion for Riv<1 : Homogeneous layer formation Dispersion for Riv<<1 : Criterion for fully homogeneous dispersion

  32. Dispersion for Riv<1 : Homogeneous layer formation Vertical volume fraction profiles, D=5mm source At t=10t, with Riv 0.0052 0.0075 0.025 1.5 3

  33. Dispersion for Riv<1 : Homogeneous layer formation Thickness of the homogeneous layer vs Riv

  34. Experimental set-up Dispersion for Riv>1 : Buoyancy dominated regime Dispersion for Riv<1 : Homogeneous layer formation Dispersion for Riv<<1 : Criterion for fully homogeneous dispersion

  35. Dispersion for Riv<<1 : Criterion for fully homogeneous dispersion Local time variations of the volume fraction D=5mm, Riv=0.0023

  36. Dispersion for Riv<<1 : Criterion for fully homogeneous dispersion Experimental critical values of Riv to reach homogeneity Critical value derived from the Cleaver et. al. (1994) correlation for the actual enclosure : Riv = 0.0025

  37. Conclusions • The 3 regimes have been identified with respect to the volume Richardson number • Buoyancy dominated regime occurs for Riv>1 • For Riv>1, Worster & Huppert model fits fairly well with the 20mm source • For Riv>1, the 5mm source gives unexpected results with much higher maximum volume fraction • For Riv<1, formation of a homogeneous layer is observed, it sickness follows the Cleaver et. al. correlation only for Riv<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

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