Gilles Bernard-Michel (CEA) Comparisons of helium and hydrogen releases in 1m3 and 2 m3 two vents enclosures: concentration measurements at different flow rates and for two diameters of injection nozzle. Gilles Bernard-Michel (CEA) Deborah Houssin (Air Liquide)

Geometry: 2 vents cavities 2 m3 cavity: 2.10 m height 1mx1m base top and bottom vent of 19cmx98cm 1 m3 cavity: 1 m height 0.995mx0.995m base top and bottom vent of 18cmx96cm

Sensors Xensor TCG3880 catharometres: 15 sensors Calibrated for he and h2 Regular spacing

Experiments, C measurements: Varying parameters Experiments, C measurements: 2 different enclosures (1m3 and 2m3) 2 different injection nozzle (4 mm, 27.2 mm) Flow rates from 5Nl/min up to 210 Nl/min 2 gas: He and H2 From plume to jet: - Richardson number 5.77·107 down to 7.08·10-4

Experimental process Reproducibility: Stationnary state: Tests performed at INERIS, AL and CEA (different facilities) 2 differents sets of sensors for some of the tests Series of tests at INERIS Different flowmeters used Stationnary state: Only stationnay data are used long enough gas injections (approx 10 min) Time averaged concentrations: Errors less than 0.3% absolute concentration - Mainly calibration

Reproducibility results with he -2 locations: INERIS and CEA Ambient temperature of 11°C (INERIS) and 20°C (CEA) Almost no air circulation Humidity of 100% (INERIS) and 55%(CEA) 2 sets of sensor (AL and CEA) 2 different calibrated flowmeters (CEA and AL) Exp. I Exp. II Exp. III Diameter Flow rate Cmax mm NL/min %vol 27 210 6.6 6.5 6.7 70 2.81 2.9 3.1 20 1.34 1.4 1.3 5 0.68 0.55 0.6

Model and scaling Scaling: Linden model: 2 homogenous layers 1D distribution outside the jet pure air layer at the bottom concentration depends on distance between injection and top vent Scaling:

Hydrogen versus helium comparisons on 2-m3 enclosure Diam mm flow rate he NL/min Cmax he %vol Cmax h2 27 5 0.68 1,06 4 0.88 1.09 20 1.34 1.83 1.41 1.73 70 2.81 3.35 2.74 3.3 210 6.6 6.17 4,69 5,44

Hydrogen versus helium comparisons on 1-m3 enclosure Injection (mm) flow rate NL/min Cmax he %vol Cmax h2 27 10 1,79 1.80 4 1.97 2.04 20 - 2.52 2.76 3.0 60 5.03 4.35 4.99 100 8.23 6.69 4.84 6.15 210 11.12 7.38

First observations Injection diameter: Gas effect: Smaller injection diameter => smaller maximum concentration at higher flow rates injection diameter has few influence for plumes regimes. Gas effect: similar behavior for plumes regimes for he and H2 with slightly higher concentrations for h2. larger spreading of maximum he concentration vs diameter than for h2. => For large injection diameter, max he concentration > max h2 concentration => For small injection diameter, max h2 concentration > max he concentration Similitude law has to be improved => Based on flow rates and another parameter (diameter?, ……)

Some first explanations ? Similitude law requires same Interface’s height We observe different interfaces heights for he and h2. The sensitive parameter in Linden’s model is the mixing Length. We need to have a closer look at this (models are based on different definitions of reduced gravity)

Thanks for your attention