Abstract
Traditional Passive Heave Compensator (PHC) requires set parameters before operation according to the specific sea conditions, making it difficult to adapt to complex and variable working environments. This study aims to enhance the environmental adaptability of classical PHC by proposing a novel concept of Dual-valve Heave Compensator (DHC) based on the traditional PHC framework. By modulating the hydraulic and pneumatic throttle valve openings dynamically, the DHC system facilitates adjustments extensively in damping and stiffness, significantly enhancing compensation performances. As an enhancement over traditional models, this study incorporates a coupled dynamic model that accounts for critical influencing factors, including gas temperature and nonlinear friction. A linearized equation for the dynamic stiffness of DHC has been developed based on the small deviation linearization method, extensively analysing the effects of pneumatic parameters on the stiffness characteristics. Furthermore, a design framework employing Latin Hypercube Sampling (LHS) design, Radial Basis Function (RBF) surrogate model, and Non-dominated Sorting Genetic Algorithm-II (NSGA-II) has been specifically developed to address the multi-objective optimization challenges presented by DHC systems. The case study indicates that the optimized DHC can achieve up to 86% compensation accuracy under a 250-ton load with harmonic excitation and offers adjustments flexibly for various operational conditions. Contrary to conventional wisdom, minimal valve openings significantly enhance compensation accuracy during some intervals of irregular wave excitation. These findings confirm the superior performance and potential of DHC relative to traditional PHCs under complex marine environments.
Published Version
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