Hydrodynamic coefficients and pressure loads on heave plates for semi-submersible floating offshore wind turbines: A comparative analysis using large scale models

Abstract

a b s t r a c tHydrodynamic forces on heave plates for a semi-submersible floating offshore wind turbine are discussed herein. A model of one of the platform columns has been built. This allows for the fitting of either a plain solid plate or the real heave plate prototype design. The latter is equipped with a vertical flap at its edge. The influence of the flap on the hydrodynamic coefficients is investigated through a results comparison with the plain solid one. The model plate diameter is 1 m, thus becoming, to the authors' knowledge, the largest for which results have been published. Results from experiments, in which added mass and damping coefficients have been measured, are presented. This experimental campaign also comprised the direct measurement of dynamic pressures on both heave plates, a fundamental magnitude for the structural design, which, until now, had not been experimentally explored for this type of system. For comparative reasons, numerical simulations were also conducted following common industry standards, both with a wide-spread frequency domain panel method (WADAM) and a RANS CFD commercial code (ANSYS CFX). Finally, results are compared with literature and consistent non-dimensionalizations are sought, with the aim of making these results useful for preliminary design purposes. The authors believe this research could benefit the offshore wind industry by improving the hydrodynamic design of the concept.

Radiation of water waves by a submerged nearly circular plate

“…One of the major inovations used in the renewable energy sector are semi-submersible floating offshore wind turbines (FOWT). These structures often have column-stabilised platforms with submerged plates which provide extra heave added mass, wave damping far removed from wave excitation [2,13].…”

Fluid Parameter Identification for Underwater Snake Robots

“…However, this will Copyright c 2018 by ASME not be the case for a snake robot with few links. WADAM and WAMIT are widely used to obtain the added mass coefficients in marine vehicles or floating structures [12], [13]. Note that WAMIT lacks a graphical user interface, and thus WADAM is considered in this paper as the 3D potential theory in WADAM is directly based on WAMIT and has a good graphical user interface.…”

Offshore turbines with bottom-fixed or floating substructures

“…Whereas this has been somewhat solved for slender-elements with the Morison approach, the issue is of particular relevance for the design of motion suppressing devices such as heave plates, commonly used with FOWTs. Typically model tests are needed to determine accurate damping coefficients, but some success has been achieved recently with both RANS and LES simulation approaches [74,75].…”