Semi-analytical study of the first order horizontal force induced by oblique waves on the array of circular columns of offshore wind turbines equipped with permeable cylinders. (1st October 2022)

• Record Type: Journal Article
• Authors: Gharechae, Ataollah; Negahdari, Mohammad Reza
• Is Part Of: Ocean engineering. Volume 261(2022)
• Publication Date: 2022-10-01
• Subjects: Horizontal wave-induced force -- Permeable and impermeable cylinders -- Array of concentric and non-concentric cylinders -- DeepCwind and OC3 wind turbines; Ocean engineering -- Periodicals; Ocean engineering; Periodicals; 620.4162
• DOI: 10.1016/j.oceaneng.2022.112043
• Languages: English
• ISSNs: 0029-8018

Abstract

Abstract: This paper studied the incident of linear oblique waves to circular columns of offshore wind turbines in conjunction with concentric and non-concentric thin permeable cylinders. The unique research objective of this work is to assess the possibility of using permeable vertical cylinders to reduce wave forces on the column of offshore wind turbines. The developed semi-analytical method benefits from the mathematical relation between Bessel functions to express the BEM-related integrals in the Fourier modes of the Hankel function and to calculate singular integrals indirectly. Moreover, Graf's addition theorem for Bessel functions was used for shifting between different coordinate systems to avoid calculating related integrals numerically. The basic geometries parameters such as permeability parameter, cylinders arrangement and the radius of the permeable cylinders, and the wavenumber on the horizontal wave-induced force were studied. The results are presented in graphs. The results indicate that covering the columns of DeepCwind and OC3 wind turbines with the permeable cylinders or using the permeable cylinders upstream helps reduce the horizontal wave-induced force at a particular permeability parameter. The results of this research are beneficial in the design of columns of offshore wind turbines and other structures with vertical piles, such as semi-submersibles. Highlights: Permeable cylinders can reduce the wave forces on offshore wind turbines. Wave force on a cylinder can be reduced by installing a permeable cylinder upstream. Two layers of permeable cylinders reduce the wave force on the DeepCwind turbine by 50%. Three permeable cylinders around the OC3 wind turbine can reduce the wave force by 50%. Installing the OC3 wind turbine inside Ocean Farm 1 can reduce the total wave force at high wavenumbers.