Design Optimization for a Truncated Catenary Mooring System for Scale Model Test

Climent Molins,Pau Trubat,Xavi Gironella,Alexis Campos

doi:10.3390/jmse3041362

Climent Molins, Pau Trubat + Show 2 more

Open Access

https://doi.org/10.3390/jmse3041362

Copy DOI

Abstract

One of the main aspects when testing floating offshore platforms is the scaled mooring system, particularly with the increased depths where such platforms are intended. The paper proposes the use of truncated mooring systems to emulate the real mooring system by solving an optimization problem. This approach could be an interesting option when the existing testing facilities do not have enough available space. As part of the development of a new spar platform made of concrete for Floating Offshore Wind Turbines (FOWTs), called Windcrete, a station keeping system with catenary shaped lines was selected. The test facility available for the planned experiments had an important width constraint. Then, an algorithm to optimize the design of the scaled truncated mooring system using different weights of lines was developed. The optimization process adjusts the quasi-static behavior of the scaled mooring system as much as possible to the real mooring system within its expected maximum displacement range, where the catenary line provides the restoring forces by its suspended line length.

Highlights

Floating offshore wind energy research is focused on developing new platform concepts that fit the necessary requirements of the stability for a wind turbine design and present competitive construction and operational costs.As in the Oil and Gas (O&G) Industry, into the design stage of the new platform concepts, the motion and loads of the platform have to be assessed and well predicted in several load combinations to ensure the reliability of the structure and the mooring system
The mooring lines are composed of two chain segments that adjusted to fit the weight per meter length computed in the optimization problem
This paper describes and assesses the use of a truncated mooring system to emulate the real one in scaled experiments when there is a limitation of the available width in the flume

Summary

Introduction

Floating offshore wind energy research is focused on developing new platform concepts that fit the necessary requirements of the stability for a wind turbine design and present competitive construction and operational costs.As in the Oil and Gas (O&G) Industry, into the design stage of the new platform concepts, the motion and loads of the platform have to be assessed and well predicted in several load combinations to ensure the reliability of the structure and the mooring system. The main approaches to predict the whole platform behavior are the numerical simulation and the physical scale models. It is still widely accepted in the offshore industry that model testing is the most reliable procedure to validate the results and to be the final benchmark for the design of a platform. The physical model testing is mainly performed in the ocean engineering basins, where the environmental conditions such as waves, currents and wind can be reproduced [1,2]. The usage of these installations would help the development of the offshore wind technology allowing the performance of the model tests in more places and reducing costs in that research field

Methods

Results

Conclusion