Search

Floating wind turbines are complex dynamic systems. The dynamics and design of such systems poses interesting engineering and scientific challenges. Although there already exist some informative and valuable reviews of this topic, there has been a lot of additional and important studies in more recent years. This topical paper reviews the main developments and research avenues currently under way, focusing on recent research literature. It adresses specific challenges of floating wind turbines and introduces the state-of-the-art and key issues focussing on the floating platform. In addition, recommendations for further research are introduced. [ABSTRACT FROM AUTHOR]

The statistical properties of the local slamming forces on the braces of a jacket structure are analyzed based on experimental data. The slamming forces from the plunging breaking waves are first reconstructed by using an inverse method together with the measured response forces in the wave test and the hammer test. The reconstructed forces from five wave cases under the same wave conditions, each including 20 waves, are investigated. The features of the forces regarding the position of the wave in the test, the case number and the location on the braces are discussed. The confidence intervals of the mean peak forces and the mean impulses are given as the statistical estimation of the slamming forces. [ABSTRACT FROM AUTHOR]

The article discusses research which analyzed the use of impulse based substructuring and massively parallel processors on offshore wind turbine (OWT) support structures. Topics discussed include the fatigue damage assessment based on stresses in structural members, impulse based substructuring and time-domain analysis.

The article discusses research which examined why the load time series from moving rotors cannot be used on design load calculations for offshore wind turbine support structures. Topics discussed include the identification of the loads as a major difficulty in using load time series from moving support structures and an overview of the reconstruction of the rotor loads.

The article discusses research which analyzed the characteristics of the slamming load for truss structures in offshore wind applications. Topics discussed include the proposed optimization based deconvolution (ODC) method and a hammer test analysis to check the plausibility of the experiment and understand the truss structure properties.

The article discusses studies regarding a bottom fixed offshore wind turbine having a jacket type substructure. Topics addressed include the structure design's reference support, the performance of coupled aero-hydro-servo-elastic simulation, and fatigue and ultimate limit state analyses conducted for substructure members. Also mentioned are the feasibility of and structural mass saved by the three-legged jacket and the jacket substructures' performance with respect to wind-wave misalignment.

The article traces the development of a model that describes the mean tower shadow effect of an upwind turbine mounted on top of a full-height truss tower wind turbine using the source panel method. It presents results including mean velocity deficits and their dependence on variation of tower parameters. It compares the numerical results with the flow field obtained by simple superposition of the potential solution for each circular member.

The article discusses a study which presented a new Markov-based method to model wind and wave conditions for offshore sites based on historical data. The method was used to simulate the operating phase of offshore wind farms. The researchers demonstrated the accuracy of modeled wind speed and wave height time series by comparing their second-order statistics and linear correlations.

The article discusses a study which compared a tubular and truss tower in the wind tunnel at the Norwegian University of Science and Technology (NTNU). It cites the use of a hot-wire anemometer in measuring the mean and turbulent wind velocity behind the towers. Results of the study showed lower energy spectra and turbulence intensities and a higher mean wind velocity for the truss tower. Findings suggest smaller loads caused by the tower shadow of the truss tower.

The article discusses a study on computational solutions for the realistic simulation of offshore wind turbine installations. Noted is the importance of numerical simulation to the evaluation of all relevant influences and properties affecting wind turbine installations. Although current modeling of wind turbine aerodynamics is based on blade element momentum theory, the theory could not be applied in highly unsteady flow and under yawed conditions.

The article discusses the results of a numerical analysis of turbulent flow past a monopile and a truss tower for a offshore downwind turbines. While a truss tower could reduce material cost it still presents tower clearance issue, which is addressed by downwind turbines. The researchers applied two different methods in implementing unsteady turbulent inflow, one of which adds turbulence to the velocity inflow profile based on turbulence intensity and length scale.

The article reports on a study concerning the optimization of jacket support structures for offshore wind turbines. Topics discussed include the proposal of a method to modify the standard genetic algorithm for optimizing jacket support structures, the challenges associated with using time-domain simulations in optimizing jacket structures and the advantages of the proposed method for modifying genetic algorithm over other performance analysis methods.