Therefore, it is essential to develop advanced numerical methods for accurate estimate of dynamic motion for CALM buoys. These features for buoy can result in dangerous motions causing fatigue damage in mooring and flowlines systems.
Compared to other floating structures like Floating Production Storage and Offloading (FPSOs) or Tensioned Leg Platform (TLP), CALM buoy is more sensitive to the response of mooring lines and oil offloading lines due to its considerably smaller inertia, damping and hydrostatic stiffness. INTRODUCTION The CALM system is widely used as an efficient and economic single point mooring system in offshore engineering applications. With the study it can be verified that the coupled method is able to provide an accurate simulation of the hydrodynamic behavior of the CALM buoy system.
#Static analysis using orcaflex code#
The coupled code was then employed for the simulation of two degree-of-freedom vortex-induced motion of a CALM buoy in uniform currents to illustrate the capability of the present CFD approach for coupling mooring analysis of offshore structures. The coupled code was calibrated first for free-decay case and compared with model test data. An interface module is established to facilitate interactive coupling between the buoy and mooring lines. The mooring system is simulated with a nonlinear finite element code, MOORING3D. In the FANS code, the fluid domain is decomposed into multi-block overset grids and the Large Eddy Simulation (LES) is used to provide accurate prediction of vortexinduced motion of the buoy.
The pros and cons of using sinker in “Catenary chain with intermediate sinker type” and “Catenary with Hinged Arm Sinker Mooring type” are discussed to clarify the design considerations. Catenary theory is applied to the static analysis, and OrcaFlex is used for dynamic analysis to consider the interaction between the floating body, mooring system and sea floor in time domain. As the procedure, the authors set the environmental design conditions assuming the coastal area of Japan and the semi-submersible type floating offshore wind turbine model, and perform static analysis to investigate the effect of parameters on the mooring characteristics, and then dynamic analysis to judge the strength feasibility of the mooring chains in storm conditions.
Although the effect of the sinker can be expected to reduce the hardening nonlinearity of the catenary characteristics statically, it is necessary to consider the dynamic effects of sinkers ascending or sitting off the sea floor. The purpose of this study is to investigate the feasibility of catenary chain mooring with sinker in the shallow waters of 50 to 100 meters depth facing the open ocean. A Study on Shallow Water Mooring System of Floating Offshore Wind Turbine with Sinker
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