The Interaction Characteristics Of Internal Solitary Waves With Floating Production Storage And Offloading System

In the South China Sea, offshore structures are in danger in rough seaconditions. Among these conditions, internal solitary waves could do hugedamage because of large amplitude and permanent propagation.Nevertheless, few researches on interaction of internal solitary waves withoffshore structures have been carried out. Considering the damagepotentially, it’s urgent necessary to launch related study.Base on systematic summary of related research in the world, theresearch including:In chapter2, experiments on the load characteristics of FPSO ininternal solitary waves have been conducted in a large-scale gravity typedensity stratified tank. Results show that the loads on the FPSO due tointernal solitary waves consist of two parts: the frictional resistance andFroude-Krylov force on the hull beneath its waterline. Base on the KdV,eKdV and MCC theories, a theoretical model for predicting these loads isestablished; It’s shown that the frictional resistance coefficient follows aninverse power function relationship with the Reynolds number. Moreover,the numerical results based on the presented theoretical predicting modelshave good agreement with experimental ones. Apractical theoretical modelfor predicting internal solitary wave loads on the FPSO is established.In Chapter3, base on the theoretical model, combining with the timedomain motion equation, a dynamical response model for single-pointturret moored floating production storage and offloading system in internalsolitary waves is established. The three-DOF motion characteristics ofFPSO in time domain due to internal solitary waves, as well as the tension characteristics of moorings have been analyzed. Results show that thehorizontal pre-tension at the top of moorings has striking effect on theamplitude of surge, FPSO has larger motion amplitudes, and last for longertime when moored by a smaller horizontal pre-tension, at the same time,the tension of mooring increases significantly. In addition, when the totaldepth invariant, the FPSO’s motion amplitudes change with the depth ofupper layer, surge and pitch amplitudes decrease when the depth of upperlayer increases, while, the heave amplitude is larger at first, then becomesmaller.Base on the experiments, an practical dynamic response theoreticalmodel is established, this research offers a certain reference for projects.