FIV2018 Paper Management System, FIV2018 Conference

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Buoyancy effect on the velocity and concentration distributions in turbulent multi-component jets issuing from a pipe with a realistic leak geometry
Majid Soleimani nia, Brian Maxwell, Peter Oshkai, Nedjib Djilali

Last modified: 2018-04-17

Abstract


Modern safety standards for hydrogen storage infrastructure must be assured before widespread public use of hydrogen can become possible. Fundamental insight into the physics of buoyant gas dispersion into ambient air from realistic flow geometries is necessary to properly predict flow structures associated with hydrogen outflow from accidental leaks and the associated flammability envelope. In the present study, a horizontal hydrogen jet was emulated experimentally using helium as a substitute working fluid issuing from a round orifice on the side wall of a vertically oriented circular tube. Particle image velocimetry (PIV) and planar laser-induced fluorescence (PLIF) techniques were employed simultaneously to provide instantaneous and time-averaged patterns of flow velocity and concentration. Effects of buoyancy on the resulting flow structure were studied over a range of Mach numbers and gas densities. Significant differences were found between the centreline trajectory, spreading rate and velocity decay of a round axisymmetric horizontal jet and that of leak-representative jets considered in the present study. It was found that the realistic leak geometry along pipeline orientation considered causes buoyancy effects to dominate much sooner than expected in a round jet. Therefore, caution is required when using round axisymmetric jet assumptions to describe the correct gas concentration, entrainment rates and, consequently, the extent of the flammability envelope of a jet emitted from realistic leak geometries.

Keywords


Hydrogen, Turbulence, Asymmetric jets, Buoyant jets, PIV, PLIF, Turbulent mixing

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