Multi-Physics Coupling Mechanism of the Dynamic Sealing Performance of the O-Ring at the Neck of a Type IV Hydrogen Storage Cylinder Under Linearly Decreasing Filling Conditions

To address the degradation of O-ring material properties and reduced dynamic seal reliability caused by excessive hydrogen temperature rise in a Type IV hydrogen cylinder due to constant-flow filling strategies, this study systematically investigates the coupled mechanism by which a linearly decreasing flow filling strategy maintains sealing performance through temperature rise regulation. By establishing a fluid–thermal–solid coupled mathematical model that comprehensively considers the Joule–Thomson effect, compression heat, gas swelling, and material nonlinear behavior, combined with numerical simulation methods, the sealing performance of the linear decreasing and constant-flow filling strategies was systematically compared across three key dimensions: temperature field distribution, evolution of seal ring material properties, and contact stress at the sealing interface. Results demonstrate that the linear decrease filling strategy effectively suppresses hydrogen temperature rise, achieving a 4.6% lower temperature increase at completion compared to the constant-flow strategy. Concurrently, this strategy mitigates thermally induced degradation of seal material properties, reducing contact stress fluctuations by 5% and significantly enhancing dynamic seal reliability. This research provides theoretical foundations and design support for optimizing filling protocols in high-performance hydrogen storage vessels.