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ÉTUDE EXPÉRIMENTALE DE JETS LIBRES, COMPRESSIBLES OU EN PRÉSENCE D'UN OBSTACLE

Abstract : The aim of this work is to experimentally investigate the hydrogen dispersion to evaluate the impact of chronic or accidental leaks that may occur in a free or in a congested environment, from a low or a high pressure tank, on a fuel cell vehicle. The leaks are assimilated to vertical turbulent and axisymmetric jets with variable density. They are issued from cylindrical orifices from 1 to 3 mm diameter. An experimental set-up was designed to investigate the leaks : hydrogen has been replaced by helium for safety reasons. It supports a 200 bar pressure and allows to position an obstacle in the jet flow. The BOS (Background Oriented Schlieren) technique has been adapted to millimeter jets and to the presence of an obstacle. Particular attention has been given to the development of this technique. The results show good agrement with the available litterature data. New similarity laws are proposed, more representative of the flows of : subsonic free jets, under-expanded free jets, and subsonic impinging (a sphere) jets. From the structure analysis of compressible under-expanded free jets, new relations are proposed to estimate the Mach disk position and diameter as well as the potential core length. Finally, two new laws are found from the analysis of flammable volume and flammable mass : they are based on the leak mass flow rate.
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Contributor : Julien Dubois <>
Submitted on : Sunday, January 2, 2011 - 10:37:03 PM
Last modification on : Tuesday, October 20, 2020 - 3:10:34 AM
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  • HAL Id : tel-00551205, version 1

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Julien Dubois. ÉTUDE EXPÉRIMENTALE DE JETS LIBRES, COMPRESSIBLES OU EN PRÉSENCE D'UN OBSTACLE. Energie électrique. Aix-Marseille Université, 2010. Français. ⟨tel-00551205⟩

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