bluuebunny/crossref_metadata_2025_split huggingface dataset:
Nacelle modeling considerations for wind turbines using large-eddy simulations
Authors: Amaral R , Houtin-Mongrolle F , Von Terzi D , Viré A 
Published: June 2024

Abstract
Two setups are used to investigate differences between modeling a wind turbine nacelle by means of an actuator-line model (ALM) and a wall-model (WM) using large-eddy simulations. One advantage of the ALM is that it requires a lower mesh refinement, making it less computationally costly. In the first setup, the nacelle is in standalone configuration and the ALM results show a much lower turbulence intensity and a significantly slower wake recovery when compared to the WM cases. In the second setup, the nacelle is in a rotor-nacelle assembly configuration and many variations of the ALM are tested in order to match the results from the experiment addressed in the OC6 task phase III. Contrary to previous findings that the nacelle might affect the turbine loads, this study shows that the improved match with the experiment stems from the increased mesh refinement in the nacelle region rather than the actual presence of the nacelle. Nevertheless, the wake profiles in the near-wake show a very good agreement between the ALM and WM, regardless of the refinement in the nacelle region. These cases also show a higher wake deficit than not using any nacelle at all.
Behavior and mechanisms of Doppler wind lidar error in complex terrain: stable flow case study at Perdigão
Authors: Black A , Lundquist J K , Montavon C , Robey R 
Published: June 2024

Abstract
A numerical experiment is carried out investigating the magnitude of biases in ground-based lidar measurements in complex flow conditions. Biases assessed include those arising from flow curvature and from the interaction of turbulence with the wind field reconstruction (WFR) algorithms used by a WindCube lidars and anemometers. RANS-CFD and WRF-LES simulations were performed for the Perdig˜ao Field Experiment site for a range of atmospheric conditions. Virtual anemometer and lidar data were generated for four locations: two near exposed ridge tops and two in low-speed regions in the valley. The LES data at these four locations show that the scalar inflation terms (the relation between scalar and vector averaged wind speed) for virtual lidar and virtual cups agree very well with predictions using perturbation theory. While the lidar errors vary greatly with location and height, the contribution from the flow curvature tends to be larger than the differences arising from scalar inflation. For one lidar/mast pair near the ridge top, comparisons between simulations and measurements are carried out for a resonant mountain wave event on June 14th, 2017, and for the whole duration of the Perdig˜ao campaign for winds perpendicular to the ridges. The lidar error during the mountain wave, a period of strong stability and low inversion height, is significantly larger than the campaign average. The sensitivity of the lidar error to atmospheric stability is confirmed by the RANS simulations, which suggests strong sensitivity of flow curvature error to stability conditions and to the shape of the wind speed profile near the top of the boundary layer.
Evaluation of wind turbine blades’ rain-induced leading edge erosion using rainfall measurements at offshore, coastal and onshore locations in the Netherlands
Authors: Caboni Marco , Slot Henk M. , Bergman Gerben , Wouters Dennis A. J. , Van Der Mijle Meijer Harald J. 
Published: June 2024

Abstract
The impingement of rain drops on wind turbine blades determines leading edge erosion (LEE) which is a factor driving high maintenance costs. In order to better quantify rain-induced LEE, we carried out detailed rainfall measurements, by means of disdrometers, in conjunction with wind speed measurements. Measurements were performed at three different Dutch sites, encompassing an offshore, a coastal and an onshore location. Based on rainfall and wind speed measurements, and assuming a virtual 15 MW wind turbine, we estimated the blade’s LEE using a fatigue-based model. Developed by means of different published rotating arm erosion data, our fatigue model relates the measured rainfall characteristics to the LEE incubation period, here assumed as the leading edge protection (LEP) system’s end of life. Assuming a polyurethane LEP system, results indicate that the blades’ incubation period is around 3.9 years at the offshore location, 6.6 years at the coastal location and 8.3 years at the onshore location. These results are connected to the higher wind speeds during rainfalls, and higher occurrences of very intense rainy events which, according to the measurements, progressively occur at the onshore, coastal and offshore locations.
Research updates on filter units for secondary stabilisation of offshore wind farm power cables
Authors: Pistani Fabrizio , Griffits Terry , An Hongwei , Tong Feifei , Draper Scott 
Published: June 2024

Abstract
This paper presents an experimental and numerical campaign that was carried out to improve the understanding of the performances of filter units, or rock bags, when used as mean of secondary stabilisation for subsea power cables in offshore wind farms. The main parameters of influence are discussed. The capabilities of the experimental facility are presented as well as the experimental approach with a description of the cases tested. The numerical models are also described. Finally some of the findings about the main mechanisms of instability are presented.
Design of a Floating Vertical Axis Wind Turbine for Wind-Wave Basin Experiments
Authors: Hossain Md Sanower , Escalera Mendoza Alejandra Stefania , Ahsan Faraz , Todd Griffith D. , Brownstein Ian , Strom Ben , Frye Alex 
Published: June 2024

Abstract
This paper presents the design and manufacturing of two novel small floating Darrieus vertical axis wind turbines (VAWT) developed for a wind-wave basin test campaign. As with typical designs, the rotor design needed to satisfy the traditional structural safety requirements (such as strain, deflection, resonant-free dynamics) from design standards along with other manufacturing and assembly constraints. In addition, for this particular design, some special conditions are present as the facility (the wind-wave basin itself) and use of existing Floating Offshore-wind and Controls Advanced Laboratory (FOCAL) semi-submersible floating platform (originally designed for HAWT test) imposed an additional set of design requirements including wind speed and size constraints, and specific, target overturning moments and rotor mass. Addressing all these constraints (facility, existing hull, structural safety, and manufacturing) presented a challenging design task in this case, thus the focus of this paper is presenting the design approach and results leading to final designs satisfying all these competing requirements. Using the presented design process, two Darrieus troposkein-shaped vertical axis wind turbines (two-bladed and three-bladed versions) were designed and manufactured, after ensuring compliance with all the design requirements. The presented study can aid researchers interested in developing similar floating turbine test campaigns.
A dynamic-simulation based workability and accessibility combined method for systematic analysis of floating wind operations
Authors: Moreno Carlos Pérez , Lange Johannes , Snedker Thor , Bayati Ilmas 
Published: June 2024

Abstract
This work aims at providing a new methodology to assess combined workability and accessibility (W&A) of a floating offshore wind turbine, that is, the capability to transfer technicians to perform maintenance work. The proposed approach accounts for site-specific met-ocean conditions and industry-typical W&A limits by virtue of significant wave height, peak wave period, and wave heading, in contrast to only considering wave height, as currently done to take operation and maintenance decisions. A multi-body model of the VolturnUS-S 15 MW floating platform with a Service Operation Vessel (SOV) is used to compute the accessibility based on time-domain simulations and motion-compensated gangway limits. An iterative algorithm is implemented to find the maximum accessible wave height for each period and wave heading. Then, based on the limiting accessibility, single-body hydro-aero-elastic simulations are used to compute the nacelle accelerations, in order to estimate workability. The accessibility is hereby found to be the most limiting factor, with significant changes depending on the peak wave period and wave heading.
Investigating North Sea Precipitation Variability: Implications for Offshore Wind Energy Siting and Condition Assessments
Authors: Ivanova Tsvetelina , Porchetta Sara , Buckingham Sophia , Helsen Jan , Van Beeck Jeroen , Munters Wim 
Published: June 2024

Abstract
Rain-driven wind turbine blade erosion, particularly in offshore locations, has been observed as early as within 5 to 7 years of turbine operation, which is below the lifetime expectancy design age of 20 to 25 year. Due to the harsh atmospheric conditions offshore, the preservation of wind turbine blade integrity has become a fundamental necessity. To address this challenge, we compare precipitation maps from two distinct sources (satellite data and a reanalysis product) over 12 years in the region of the North Sea, and we pursue insights into local weather patterns through temporal analysis. This integrated approach enhances the understanding of offshore conditions by focusing on precipitation and wind speed data analysis in time and space. This enables more efficient wind farm planning, operation and maintenance, as well as wind farm siting via informed decisions that account for the risk of rain-driven blade erosion and allow for mitigation measures.
Cost optimization of dynamic cable lazy wave configurations for floating offshore wind turbines
Authors: Syed Huzaifa , Muggiasca Sara 
Published: June 2024

Abstract
This research aims to design a low-cost dynamic cable lazy wave configuration at different curvature factors by adopting an integrated approach to optimally size the length of different sections of the dynamic cable accounting for maximum allowable tension, maximum allowable curvature, minimum allowable sag position and maximum allowable hog position. The research explores trade-offs associated with the increase in costs as curvature factor decreases. The configuration is subjected to Near, Far and No offset scenarios to analyse the impact on costs and its performance. The assessment includes determining configuration costs and optimal lengths at different curvature factors for each scenario. Observations reveal that the hang-off point consistently experiences the highest curvature across the arc length in all configurations and scenarios. Optimal configurations for Far scenario outperform configurations designed for No offset scenario when subjected to the remaining two scenarios. Optimal configurations of Near scenario failed to adhere to the maximum allowable curvature limit when subjected to Far and No offset scenarios. The study highlights the sensitivity of the curvature factor to the ratio of lengths of each section in the configuration. These results indicate that a configuration designed for Far offset is more likely to perform well under all scenarios due to its unique section length ratios. The results also portray the possibility of a fit configuration with lower number of buoyancy modules.
Reduced-order modelling of floating offshore wind turbine: Aero-hydro-elastic stability analysis
Authors: Meng Fanzhong , Lio Alan W.H. , Riva Riccardo 
Published: June 2024

Abstract
A reduced-order aero-hydro-elastic analysis tool for performing the stability analysis on floating offshore wind turbines is presented. In this work, a high-order non-linear aero-elastic model initially developed for onshore wind turbines is extended by utilizing a super-element body, which models the floating platform, the mooring system and the hydrodynamic contributions. The turbine structure is modelled by a Finite beam Element Method, and the aerodynamic loads are modelled by the Blade Element Momentum method coupled with a Beddoes-Leishman type dynamic stall model in a state-space formulation. The linearization is performed around steady state equilibrium at any given mean wind speeds, rotor speeds and collective blade pitch angles utilizing Coleman transformation to remove the periodic terms. The order reduction is based on two projections to reduce the number of structural states and aerodynamic states separately using the structural modal project matrix and the aerodynamic shape functions. Concurrently, we investigate the effect of unsteady aerodynamic states on the stability analysis of a floating wind turbine. The results show the low-order aero-hydro-elastic model expands the scope of numerical tools available for conducting structural modal analysis and aero-hydro-elastic stability analysis on floating wind turbines.
Techno-Economic Analysis Incorporating Intelligent Operation and Maintenance Management: A Case Study of An Integrated Offshore Wind and Hydrogen Energy System
Authors: Li Honglin , Li Mingxin , Carroll James , Zhang Jie 
Published: June 2024

Abstract
In this study, a comprehensive examination of wind-hydrogen energy systems is conducted through detailed techno-economic analysis and sensitivity analysis. The primary emphasis is on optimizing operation and maintenance (O&M) strategies and understanding the impacts of market dynamics. Utilizing Monte Carlo simulations, we first identify the optimal intelligent O&M plan, leading to significant reductions in annual O&M costs ($39.9/MW) and downtime (6.59 days per turbine) compared to conventional methods. The incorporation of prognostics and health management (PHM) further demonstrate a notable impact, leading to a 9.9% reduction in O&M costs and a 10.7% decrease in downtime. In the broader context, these outcomes translate into reductions in the O&M expenditures, total lifecycle costs of the system, Levelized Cost of Hydrogen (LCOH) and Levelized Cost of Energy (LCOE) by 3.9%, 0.75%, 2.4%, and 1.8%, respectively, highlighting the economic benefits of intelligent O&M strategies. The extensive sensitivity analysis, encompassing 54 scenarios, delves into the effects of maintenance strategies, hydrogen prices, wind energy share, and subsidies, revealing nuanced insights into cost savings and operational efficiencies. Notably, intelligent maintenance and favorable hydrogen subsidies effectively reduce LCOH, while the interplay between wind energy share and hydrogen pricing influences system profitability and efficiency, underscoring the complex dynamics at play in optimizing renewable energy systems.
Incorporation of floater rotation and displacement in a static wind farm simulator
Authors: Riva Riccardo , Pedersen Mads M. , Pirrung Georg , Bredmose Henrik , Feng Ju 
Published: June 2024

Abstract
Thanks to the development of several wake models, recent years have seen a huge development of static wind farm simulators. As new wind farms are planned for deep waters, there is a need to extend these tools to account for the floater rotation and displacement. In this work, we have addressed this task by selecting a reduced set of environmental conditions and generating a database from medium-fidelity simulations, whose computational cost has been reduced by developing a new static solver. Then, we trained neural networks and embedded them in PyWake via a model-agnostic interface. Finally, the wake deflection due to rotor tilt has been modeled by extending a state-of-the-art model. The results indicate that the rotor can move downwind by up to 10% of the diameter and rotate in tilt by 3° at rated wind speed.
Exploring memory mechanisms for friction fatigue in vibratory pile driving
Authors: Tsetas Athanasios , Tsouvalas Apostolos , Metrikine Andrei 
Published: June 2024

Abstract
This paper studies the mechanism that leads to the reduction of frictional soil reaction forces during pile driving, termed friction fatigue. We focus on axial vibratory driving, an environmentally friendly monopile installation method, and examine two friction fatigue formulations, i.e. a penetration-based and a cyclic memory mechanism. Friction fatigue plays a pivotal role in pile drivability and post-installation bearing capacity for piles installed via axial vibratory driving. Through numerical analyses and validation against field data from onshore experiments, the efficacy of these memory mechanisms is assessed. The results reveal that the proposed cyclic memory mechanism provides consistently more accurate predictions than the corresponding penetration-based approach, offering a promising option for modelling friction fatigue in vibratory driving. This study advances our understanding of friction fatigue in the context of vibratory driving for offshore monopile installation, emphasizing the need for further numerical and experimental works in this topic.
Spatial Optimization for Energy Island Location and Cable Routing Considering Offshore Zoning
Authors: Verikios G. , Janssen F. , Satish A. , Liu Y 
Published: June 2024

Abstract
The energy hub concept presents a compelling opportunity to channel electricity from offshore wind farms to the grid, facilitating cross-border energy trading and conversion. However, one of the main challenges lies in the strategic identification of a suitable energy island location and the establishment of an interconnected cable routing path. Part of the complexity arises from the need to navigate offshore zoning regulations and accommodate various spatial uses within the offshore area. This paper exhibits a case study to explore the spatial optimization for a potential offshore energy hub in the North Sea. It aims at finding out an optimal spatial configuration of the offshore energy hub, such that the island location and the associated cable routing do not infringe upon keep-out zones while strategically positioning the hub closer to high-capacity wind farms. To achieve this goal, detailed geographical data incorporating offshore zoning information is leveraged for spatial optimization. The Dijkstra’s algorithm is then applied to identify the optimal island location and cable routing path. The effectiveness of this spatial optimization methodology is demonstrated through a case study involving offshore wind farm sites in the North Sea. Given the real geographical data, simulation results underscore the efficacy of the Dijkstra’s algorithm in determining the optimal energy hub layout. In particular, an optimal spatial design is achieved, based on cable lengths, asset capacities, offshore zoning and island/platform location for a potential offshore energy hub in the North Sea while ensuring compliance with keep-out zoning regulations.
Corrosion fatigue analysis of NREL’s 15-MW offshore wind turbine with time-varying stress concentration factors
Authors: McAuliffe James , Baisthakur Shubham , Broderick Brian , Fitzgerald Breiffni 
Published: June 2024

Abstract
Over the last twenty years, significant development in wind turbine technologies has led to a dramatic increase in the scale of wind turbines with many now beginning to be installed in offshore locations. Consequently, modern multi-megawatt offshore wind turbines are exposed to increased cyclic loading in addition to an increased risk of corrosion attack. The combination of these two factors may result in wind turbine support structures becoming increasingly vulnerable to fatigue corrosion. The objective of this work is to investigate the impact of material thinning in fatigue-prone areas with respect to fatigue loading and ultimately to examine the potential repercussions on the lifespan of wind turbine support structures. To achieve this, a composite model is constructed coupling results from a multi-body structural dynamic model with time-varying Stress Concentration Factors (SCF) obtained from a finite element model (FEM) of NREL’s 15-MW monopile-based offshore wind turbine. The nonlinear aeroelastic multi-body dynamic model of the wind turbine is used to generate stress time histories for a set of environmental conditions based on the operational conditions of the wind turbine. The finite element model of the wind turbine is then used to identify fatigue-vulnerable regions in the wind turbine support structure and calculate SCFs for these specific areas. The integration of SCFs into the fatigue calculations reduced the lifespan of the turbine tower by a factor of 4, demonstrating the importance of precisely modelling such local stress concentrations for effective fatigue analysis. A novelty of this work arises in the ability of the finite element model to update the SCFs of the fatigue-prone areas over time as corrosion-induced wastage alters the substructure’s geometry, thereby inducing a global redistribution of stresses. A fatigue analysis is carried out availing of the SCFs which vary annually in addition to the stress-time histories produced by the multi-body dynamic model. The results illustrate that the phenomenon of corrosion thinning induced an 8.9% reduction in the fatigue life of the wind turbine tower, thus emphasising the significant importance of proactive maintenance strategies to mitigate the impact of corrosion.
Development of a numerical model for floating Vertical Axis Wind Turbines
Authors: Ghigo Alberto , Sirigu Massimo , Collu Maurizio , Bracco Giovanni 
Published: June 2024

Abstract
Vertical Axis Wind Turbines (VAWTs), which are primarily used in small-scale applications, such as in remote or urban areas, could be particularly promising for floating offshore wind projects, where they offer benefits like increased stability, lower maintenance costs, and the potential for closer spacing due to lesser aerodynamic wake effects. However, to be competitive with floating HAWTs, scaling up VAWTs size is an urgent necessity to facilitate large-scale industrialization. To achieve this goal, the development of tools capable of assessing VAWT performance in challenging offshore environments is crucial. This work aims to introduce a time domain model of a floating VAWT, developed within the Matlab-Simscape environment. The model comprises a floating platform, a wind turbine, and a mooring system. The aerodynamics is simulated using the Double Multiple Stream Tube method, which relies on Blade Element Momentum (BEM) theory. Hydrodynamics is modelled using WEC-Sim, a Simscape library developed by NREL and SANDIA. Among the main advantages of the model are the flexibility and low computational time. The article presents a case study involving a semi-sub foundation, the OC4-DeepCwind, supporting a Darrieus H-rotor VAWT. The results obtained are compared with those from QBlade Ocean, an open-source tool developed by TU Berlin, demonstrating a good agreement between the two codes.
Influence of wave spreading on offshore wind turbine design: IEA 15-MW scenario
Authors: Ryan Gerard V. , McAdam Ross A. , Adcock Thomas A. A. 
Published: June 2024

Abstract
Offshore ocean waves are directionally spread, whereby the propagation of energy travels in different directions. Despite this multi-directionality, the use of 3-dimensional wave models for loading on fixed offshore wind turbines has been limited. This is partially due to the common assumption that uni-directional sea-states are conservative within a design philosophy. This may not always be true given that in operating conditions the amount of aerodynamic damping in the side-side direction is much lower than the fore-aft direction. This paper aims to address this issue by providing the influence of wave spreading on various offshore wind turbine design scenarios: fatigue, ultimate and service limit state design. This study demonstrates that wave spreading indeed results in more fatigue damage for operating load cases. Despite this, the overall fatigue and ultimate limit state utilisation is still reduced when a wave spreading is adopted.