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Dispersion of instantaneous jets
Author(s) -
Landis John G.,
Linney Robert E.,
Hanley Brian F.
Publication year - 1994
Publication title -
process safety progress
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.378
H-Index - 40
eISSN - 1547-5913
pISSN - 1066-8527
DOI - 10.1002/prs.680130117
Subject(s) - dilution , dimensionless quantity , mixing (physics) , dispersion (optics) , mechanics , momentum (technical analysis) , flashing , materials science , chemistry , meteorology , analytical chemistry (journal) , thermodynamics , physics , chromatography , optics , finance , quantum mechanics , metallurgy , economics
When a gas under pressure is released, the momentum imparted to it causes the gas to mix with the surrounding air. A series of tests was carried out, and a model was used to determine the dynamics of the gas and air mixing for releases of a very short time duration. The amount of mixing that occurs when a pressurized fluid is released was determined by filling a container with varying mixtures of fumed silica and nitrogen, by bursting the container's rupture disks at fixed pressures, and by measuring the cloud velocity, location, and size at successive time intervals. A two‐stage model was developed to predict the location, size, and fluid concentration (i.e., degree of dilution) of the cloud resulting from the release of a two‐phase fluid composed of a non‐flashing or non‐evaporating dense phase. The dimensionless form of the model (ρ 0 u 0 t/ρ 0 r 0 ) was found to correlate the cloud properties over initial pressures ranging from 3.1 to 70.7 barg (46 to 1025 psig), and gas quality ranging from 0.2 to 0.7 (gas mass fraction). Both the model and the data showed that the initial fluid concentration was reduced by factor of 300 to 1000 as a result of the momentum imparted mixing. This dilution is in addition to that resulting from atmospheric dispersion. Combining the predicted dilution effect from the instantaneous release with atmospheric dispersion to predict both near field and far‐field concentration is an important application of this two stage model.