Offshore Support Structure

Overview

Offshore wind turbines are flexible, dynamic structures. Wave loading, wind loading and the action of the turbine controller are all coupled by the dynamic response of the structure, exerting a powerful influence on fatigue and extreme loads. To optimise the design of the support structure - and minimise cost - it is necessary to account for this coupling by using an integrated approach to the calculation of design loads.

Bladed provides an integrated, time-domain model for the design and analysis of both offshore and onshore wind turbines. The Offshore Support Structure module adds an advanced support structure model which allows multiple-member, space-frame support structures to be designed and analysed.

Structural modelling

• Any space-frame structure can be defined – not restricted to generic support structure types.
• Floating structures can be defined with mooring options either represented by non-linear springs or by tension leg model.
• Interactive 3D plot of the defined structure allows easy checking.
• Foundation representations include rigid, linear spring and non-linear spring models. A ‘p-y’ representation of piled foundations can be analyzed using the non-linear spring model.

Wave and current modelling

• A range of regular and irregular wave models including linear Airy, Stream Function and Constrained NewWave.
• Pierson-Moskowitz and Jonswap wave energy spectra plus the ability to enter user-defined wave energy spectra from site measurements.
• Near-surface, sub-surface and near-shore current profiles.

Calculation basis

• Time-domain simulations ensure accurate representation of non-linear effects.
• Modal superposition technique provides fast simulations.

Integrates directly with other Bladed features

• Rigorous modelling of rotor aerodynamics, including dynamic inflow and stall hysteresis.
• Accurate representation of the three-dimensional turbulent wind field.
• Automatic load case set-up and post-processing using wave scatter diagram.
• Batch queue facility to manage large numbers of simulations and post-processing calculations.
• Extensive post-processing features – now including extrapolation of extreme loads as required by IEC Ed. 3.

Code checking

• A link to ANSYS® offshore products ANSYS® Fatjack for beam joint fatigue, ANSYS® Beamcheck for member checks on framed structures, ANSYS® ASASTM Offshore (which includes the code checking capabilities of both tools).
• An interface to SACS provides a fast exchange of geometry models and turbine analysis results for comprehensive time history fatigue analysis, joint can analysis and detailed member code checks in SACS.