Floating Spar-Type Offshore Wind Turbine Hydrodynamic Response Characterisation: a Computational Cost Aware Approach

Abstract

The hydromechanics analysis of floating offshore wind turbines is a fundamental and time consuming part of the design process, traditionally analysed with methods of computational fluid dynamics. In this work, an alternative computational framework is suggested, able to significantly accelerate the design process with minimal accuracy loss. Through the use of a state-ofthe-art potential-flow code, a surrogate model is developed with the aim to approximate the Response Amplitude Operators of any arbitrary floating offshore wind turbine of the spar buoy type. The results, measured in terms of accuracy and computational effort, demonstrate that this approach is able to approximate the potential-flow solver with very high accuracy at a fraction of the computational cost.

Physically plausible propeller noise prediction via recursive corrections leveraging prior knowledge and experimental data

“…DDMs have proven to be valuable instruments in several maritime applications (Miglianti et al, 2020;Coraddu et al, 2020Coraddu et al, , 2019Cipollini et al, 2018;Coraddu et al, 2017;Wang et al, 2021;Vesting and Bensow, 2014;Coraddu et al, 2021b;Sha et al, 2022;Banan et al, 2020;Shao et al, 2021;Fan et al, 2020), and have also been employed by several researchers in propeller design and analysis. Koushan (2000) was among the first to explore the use of DDMs in propeller hydrodynamics, developing a Neural Network (NN) to predict propeller induced pressure pulses utilising 470 model-scale tests.…”

“…As a first advantage, they can rely on and fully exploit both physical knowledge of the phenomena and historical data to deliver both accurate and physically plausible results (Coraddu et al, 2021a). As a second advantage, they can be quite efficient in making predictions, allowing to include them in automatic tools for design optimisation (Coraddu et al, 2020). Finally, they reduce the need for historical observations, thanks to the exploitation of the prior knowledge about the phenomena, reducing consequently the computational effort needed to build them.…”

Parametrisation Scheme for Multidisciplinary Design Analysis and Optimisation of a Floating Offshore Wind Turbine Substructure – OC3 5MW Case Study

“…Wadam uses the Morison equation [18] and first and second order 3D potential theory [18] for the wave load calculations in which the incident wave is an Airy wave and the analysis is performed in the frequency domain. The resultant system of equations of motion, in the frequency domain, for a FOWT body in regular waves is highlighted in equation ( 1), [20]- [21].…”

“…Where 𝑀 𝑘𝑗 is the total system mass matrix, 𝑎 𝑘𝑗 is the hydrodynamic added mass coefficient, 𝑏 𝑘𝑗 is the radiation damping coefficient without the consideration of viscous forces, and 𝑐 𝑘𝑗 is the sum of the hydrostatic and mooring stiffness coefficients. 𝜉 𝑗 is the j-th degrees of freedom displacement (rigid platform global response), 𝜂 is the wave amplitude and 𝑋 𝑘 is the first order wave load transfer function [20]- [21]. The complex response transfer function between the amplitude of the wave and the amplitude of oscillation in the oscillatory degrees of freedom is highlighted in equation (2).…”

Computationally Aware Surrogate Models for the Hydrodynamic Response Characterization of Floating Spar-Type Offshore Wind Turbine

“…For this reason, in this work, building upon the authors' previous work [41] on surrogate model for Response Amplitude Operators (RAOs), we will focus on the prediction of the hydromechanics characteristics. Contrarily to the RAOs, the hydromechanics characteristics depend only on the wet geometry of the platform, on the wave frequency and, for the wave loads transfer functions, on the wave direction, i.e., they do not depend on the mass, nor on the center of gravity or moments of inertia, which can be usually obtained with little computational cost [42].…”