Experiment and visualization of omnidirectional acoustic propagation for high-pressure hydrogen storage leakage in unconfined environments

Abstract

Hydrogen, a clean energy source, is pivotal in achieving carbon neutrality but presents safety challenges due to its high diffusivity and flammability. This study explores hydrogen leakage acoustics and spatial characteristics under high-pressure, unconfined conditions. Helium, validated as a surrogate gas with a sound pressure difference of <5 dB, was used for safe experimentation. Using Background Oriented Schlieren (BOS) imaging, significant directional and spatial dependencies were identified, with optimal detection at 1.5 m height and highest sound levels between 300° and 360°. The influence of nozzle geometry was also highlighted, with flat nozzles producing progressively higher sound pressure levels compared to circular ones. Threshold flow rates for audible detection were determined, approaching the maximum permissible leakage limit of 118 NL/min in noisy environments. These findings provide a foundation for safer and more effective hydrogen detection systems.