Performance evaluation of roll motion in offshore green hydrogen floating production storage and offloading (H2FPSO) with internal flow in liquid-hydrogen storage tanks

This study investigated the design and motion characteristics of a floating offshore green hydrogen floating production and storage platform (H2FPSO) that uses offshore wind energy to produce, liquefy, store, and transport green hydrogen. The focus was on the influence of the internal flow within Type-C liquid-hydrogen (LH₂) storage tanks on the roll motion of the platform. This study examined the impact of different tank filling ratios through numerical simulations and physical model tests conducted in the Deep Ocean Engineering Basin (DOEB) of the Korea Research Institute of Ships & Ocean Engineering (KRISO). Two storage tank models, with capacities of 2,000 and 3,000 m³, were analyzed under both static and dynamic fluid motion scenarios. The interaction between the internal fluid dynamics and roll motion was assessed using free-decay tests and high-speed imaging. The results revealed a notable coupling effect when the natural period of the internal flow coincided with the platform's natural roll period, particularly in the 3,000 m³ tank. Moreover, as the roll amplitudes increased, the damping coefficient decreased owing to the phase discrepancies between the internal flow and platform motion. While the 2000 m³ tank exhibited minimal coupling effects, the 3,000 m³ tank exhibited substantial coupling under specific filling conditions.