Due to the low density of hydrogen,the buoyant diffusion behavior of hydrogen-mixed natural gas after leakage under the action of ocean waves and currents differs from that of pure natural gas,and its leakage and diffusion characteristics need clarification.The process of hydrogen-mixed gas leakage diffusion in submarine pipelines under wave-current interaction was numerically simulated using computational fluid dynamics methods.The results indicate that the gas leakage process can be divided into three stages:initial leakage,upward buoyancy,and lateral migration.When the hydrogen mixing ratio φH2 is less than 50%,the trajectory of hydrogen bubbles is significantly influenced by natural gas bubbles.The changes in gas buoyancy height and diffusion diameter are positively correlated with time,and with the increase in hydrogen mixing ratio,the time required for the leaked gas to reach the liquid surface increases.Both natural gas and hydrogen bubble diameters gradually increase during ascent,with the buoyancy speed of both increasing and then decreasing with increasing buoyancy height,although natural gas bubble buoyancy speed decays more rapidly.The diameter of hydrogen bubbles increases with the increase in hydrogen mixing ratio,while the diameter of natural gas bubbles decreases with the increase in hydrogen mixing ratio.Both their ascent speeds exhibit a trend of increasing and then decreasing with increasing hydrogen mixing ratio,with the ascent speed of hydrogen bubbles greater than that of natural gas bubbles.The larger the wavelength and current velocity,the larger the diffusion diameter of the leaked gas.
gas leakagehydrogen-mixed transmissionleakage diffusionbubble buoyancyhydrogennatural gassubmarine pipelines
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