The DeRisk design database: extreme waves for Offshore Wind Turbines

Pierella, F. (Speaker)

Activity: Talks and presentationsConference presentations

Description

The substructures for offshore wind turbines are a central element for targeted cost reductions in offshore wind energy. As rotor dimensions increase, the substructures become larger, and extreme loads from storm waves can become design drivers. Therefore, the industry needs
accurate and reliable (de-risked) design methodologies for extreme waves. The objective of the current work is to propose an alternative to the current industry standard for simulation of extreme waves for Ultimate Load States (ULS) estimations. In the standard “constrained wave approach”, a 50-year regular stream function is embedded into a background irregular linear sea realization, as an attempt to account for nonlinearity of
the largest waves. While this approach is intuitive and fast, it has shortcomings. First, the maximum load on a flexible structure is not necessarily associated with the largest waves.
Moreover, real life extreme waves usually propagate on sloped bottoms, have nonsymmetric crests, and in particular conditions they may break.
In the current work, in the framework of the DeRisk Danish project (2015-2019), we use the fully nonlinear solver OceanWave3D (OW3D), developed by DTU, to create a database of shallow water kinematics associated with 10, 100 and 1000 years storms. The storms are
generated in deep water, and evolved through a gentle 1:100 slope. As the domain shoals, the nonlinear processes redistribute the wave energy. The kinematics is then sampled at a number of shallow water locations and stored in a large database. These data can be used to calculate
the response of offshore wind turbines via suitable aeroelastic codes. The results of the database can be extended to different sets of boundary conditions using the Froude Scaling law.
Period16 Jan 2019
Event titleEERA DeepWind'2019: 16th Deep Sea Offshore Wind R&D Conference
Event typeConference
LocationTrondheim, Norway
Degree of RecognitionInternational