Session: 08-06-01 non-presentations

Paper Number: 128079

128079 - Numerical Assessment of the Dynamic Loading on the Deepcwind Platform Mooring System Under Realistic Waves and Current Conditions 

The study of hydrodynamics in the characterization of floating offshore wind turbine (FOWT) platform responses has accumulated substantial research attention. However, waves and currents are usually studied as separate phenomena, and their interaction has not been thoroughly explored due to the difficulty in conducting such research. Specifically, in the case of FOWTs, wave-induced oscillations play a pivotal role in the stability of both the platform and the hosted wind turbine. The persistent shift in surge position induced by current action can have undesired effects on two critical parameters influencing anchoring system design. The former arises from the platform establishment of a new equilibrium at its displaced position that entails a consistent pitch induced by such imbalance. The latter, the skewness in the platform equilibrium position, will directly contribute to sharpening the tension patterns in the mooring system. Additionally, another aspect that is as much as pertinent concerns the wave frequency when waves interact with current. This transformation can result in a critical shift in the demand spectrum, which may get close to the heave natural frequency, thus increasing the response of the system.

In this study, we perform a numerical investigation to assess the impact of sea states characterized by regular waves combined to currents (i.e., following or opposing) on the mooring tension. Following the methodology outlined in [1], the DeepCwind platform was subjected to testing using the configuration proposed during the OC6 experimental campaign. In this setup, the platform was stabilized by a system of inclined, pretensioned lines. Two sets of waves are employed to perform a sensitivity analysis, considering both increasing wave heights and extension in wave periods, combined to the presence of sea currents. By contrasting the newly obtained results with the data from prior investigations, we aim at shedding light on the influence of these environmental factors. The numerical investigation will be performed using the meshless software DualSPHysics [2], for which a hydrodynamical validation for DeepCwind is presented in the reference paper [1]. Combined wave and current velocity field will be generated using Dirichelet open-boundary conditions, as shown in [3].

[1] Tagliafierro B. et al. (2023). Numerical validations and investigation of a semi-submersible floating offshore wind turbine platform interacting with ocean waves using an SPH framework. Applied Ocean Research, 141, 103757. https://doi.org/10.1016/j.apor.2023.103757

[2] Domínguez, J.M. et al. (2022). DualSPHysics: from fluid dynamics to multiphysics problems. Comp. Part. Mech. 9, 867–895 . https://doi.org/10.1007/s40571-021-00404-2

[3] Capasso, S. et al. (2023). Regular Wave Seakeeping Analysis of a Planing Hull by Smoothed Particle Hydrodynamics: A Comprehensive Validation. Journal of Marine Science and Engineering, 11, 700. https://doi.org/10.3390/jmse11040700

 

Presenting Author: Salvatore Capasso Università degli Studi di Salerno

Presenting Author Biography: I am a Civil Engineer and Architect, graduated at the University of Salerno. I am currently involved in the PhD Program of the Civil Engineering Department at University of Salerno, investigating Fluid-Structure Interaction using an high-fidelity CFD open-source code, DualSPHysics, based on the Smoothed Particle Hydrodynamics technique. As part of the collective DualSPHysics solver project, I am actively collaborating to extend the applicability of the code to various field of Civil engineering, including flexible structures and realistic environmental conditions for offshore structures for renewable energy harvesting.

Authors:

Bonaventura Tagliafierro Universitat Politècnica de Catalunya
Salvatore Capasso Università degli Studi di Salerno
Oronzo Dell'edera Politecnico di Torino
Francesco Niosi Politecnico di Torino
Madjid Karimirad Queen's University Belfast
Malin Göteman Uppsala Universitet
Iván Martínez-Estévez Universidade de Vigo
José M. Domínguez Universidade de Vigo
Alejandro J C Crespo Universidade de Vigo
Giacomo Viccione Università degli Studi di Salerno
Corrado Altomare Universitat Politècnica de Catalunya
Moncho Gómez-Gesteira Universidade de Vigo