Coupled Mooring Analysis for a Deep Water CALM Buoy

Abstract

The effect of the mooring loads on floator motions can be significant for small water plane are floaters like CALM buoys. Not only does the mooring system contribute to the static restoring force components, but the dynamic behaviour of the mooring lines also affects the inertia and damping of the moored CALM buoy. The results from model tests with a moored CALM buoy were compared with the results from two series of time-domain computer simulations. First, fully dynamic coupled simulations were carried out, in which the interaction between the floater motions and the dynamic mooring line loads was modelled for all 6 modes of motion. Second, quasi-static simulations were carried out, in which only the (non-linear) static restoring force characteristics of the mooring system were taken into account. The comparison of results from the simulations and the model tests clearly indicates that the fully dynamic coupled simulations show a much better correspondence with the model test results than the quasi-static simulations. It is concluded that for the simulation of the behavior of a moored CALM buoy in waves a fully dynamic coupled mooring analysis is essential.

Strength of submarine hoses in Chinese-lantern configuration from hydrodynamic loads on CALM buoy

“…Negligible mass, zero inertia and zero mass moments of inertia are applied for the cylinders. The drag forces as a result of the hydrodynamic loads due to drag and inertia on both the mooring lines and the submarine hoses are calculated using a set of equations as those in (Cozijn & Bunnik 2004).…”

“…However, there are still challenges with damping calculation, resulting in that some procedures are proposed. These include quadratic drag linearization ( Salem et al 2012), quadratic relative velocity (Berhault et al 2004), quadratic absolute velocity (Cozijn & Bunnik 2004) and some other formulations using Morison Equation (Morison et al 1950;Brebbia & Walker 1979;Chandrasekaran 2015;Sarpkaya 2014). In this respect, more attention has been focused on CALM buoys than on hoses (Cozijn et al 2005;Roveri et al 2002;Wang & Sun 2015).…”

Mathematical Modelling of Bonded Marine Hoses for Single Point Mooring (SPM) Systems, with Catenary Anchor Leg Mooring (CALM) Buoy Application—A Review

“…Such weather conditions are unavoidable during full-scale field tests except in real-time and under good controls [95]. Since the dynamic behavior of mooring lines is scale-dependent, perfect dynamic similitude between full-scale models and small-scale physical models is difficult to achieve, which is a major roadblock in physical testing of hose-mooring systems [96][97][98][99][100][101][102][103][104]. MMs are becoming more relevant for full-scale system analysis due to the great challenges with scaling the impact of practical mooring system tests, as well as the related expenses.…”

Design and Analysis of a Mooring Buoy for a Floating Arrayed WEC Platform

“…CALM buoys have been applied widely over decades to moor the tank vessels to offload oil or gas liquids [23][24][25][26]. However, even though the CALM buoy mooring technology is mature, the CALM buoy to date is only utilized for oil or gas transfer.…”