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Contenido archivado el 2022-12-27

INTEGRATED TENSION LEG PLATFORM SIMULATOR

Objetivo

MCS propose the development of a general purpose simulation package, named ITLPS for the integrated analysis and design of the motions and forces on the complete TLP structure including platform, risers and tethers. The structural system will be discretised by the finite element technique in three dimensions with platform and tether/riser elements as one integrated spaceframe. An additional innovation will be the capability of modelling the risers as flexible beam elements attached to the platform. All wind, wave and fluid current loading functions, including higher order terms such as slow drift and damping forces, will be included in a computationally efficient form based on a consistent set of hydrodynamic assumptions. Pre-and post-processors including a customised database will be attached such that the system may be readily accessed by design engineers.
An integrated spaceframe finite element model of a TLP including superstructure, deck, columns, pontoons, tethers and risers may be assembled using three-dimensional beam-column finite elements. Semi - analytical solutions have been obtained for the wave potentials due to diffraction and radiation about vertical open-bottom columns and rectangular submerged pontoons. Static and dynamic spectral wind loading from an arbitrary direction may be specified for an element set or group; this set models the superstructure as a spaceframe with special element properties relating to the wind area and local parameters. Similarly a formulation for lift forces due to vortex shedding on tethers and risers is available.
The overall equilibrium equations in the frequency domain for the TLP may be solved about the original undeformed equilibrium position and also about a static nonlinear configuration due to large drift motions of the TLP. A procedure for the stochastic linearisation of noncollinear random waves and current is developed for the hydrodynamic forces on the tethers and riser sections. Data is presently being collected for the testing and verification phases of the project.
The major result to date is the derivation of the semi-analytical functions for the hydrodynamic loads on the TLP columns and pontoons. These are not available elsewhere for the configurations in question and are expected to overcome the excessive computational problems associated with competing computer-based numerical methods. The other results are associated with the implementation and testing of the load modules for wind loading, vortex shedding, spaceframe motions and various solution schemes. The major remaining step is to integrate all the load modules into the finite element package and execute the ITLPS suite using realistic field data.
A number of test cases have been executed for deepwater areas, such as the very hostile environment of the Porcupine Bank off the West coast of Ireland. The Irish certification authority, EOLAS, has validated the results.
The project was carried out in five stages. These were:
1. THE DEVELOPMENT
Development of an integrated spaceframe finite element model of complete TLP: columns, pontoons, tethers and risers, with solution in the frequency domain.
2. THE DERIVATION
The derivation of semi-analytical solutions for wave forces, added and potential dampening coefficients for large body structures, using diffraction theory.
3. A LINEAR FREQUENCY DOMAIN SOLUTION
Linear frequency domain solution about a nonlinear large deflection static position, with all environmental loads. This is coupled dynamic analysis in the frequency domain using a combination of diffraction theory for pontoons and columns, and Morison's equation for tethers and risers.
4. THE COLLECTION
Collection of environmental data and execution of test case for the Porcupine, offshore Ireland.
5. THE INDEPENDENT ASSESSMENT
Independent assessment of ITLPS capabilities by EOLAS, the Irish certification authority.

Convocatoria de propuestas

Data not available

Régimen de financiación

DEM - Demonstration contracts

Coordinador

MCS INTERNATIONAL
Aportación de la UE
Sin datos
Dirección
BUTTERMILK WALK 2-3
Galway
Irlanda

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Coste total
Sin datos