bluuebunny/crossref_metadata_2025_split huggingface dataset:
Double roller negative stiffness mechanism seat suspension optimization design and vibration analysis
Authors: Zuo Xidong , Chen Qingzhang , Li Youshi 
Published: June 2024

Abstract
To further improve the vibration isolation performance of automobile seat suspension and the riding comfort of automobiles, this paper uses the double roller negative stiffness mechanism (NSM) to calculate the seat suspension with quasi-zero stiffness (QZS) characteristics. The influence of the structural parameters on the QZS characteristics is simulated and analyzed, and the structural parameters are optimized by the orthogonal design method. The effectiveness of the optimization was verified by analyzing the dynamic response of the seat suspension system. The results show that the natural frequency of the vibration isolation system of the seat suspension decreases, the vibration isolation band widens after the introduction of the double roller NSM, and the vibration isolation effect is improved under low-frequency excitation.
Simulation study on the damage behavior of tantalum target plates under high-velocity projectile impact
Authors: Wang Yuntian , Yang Min , Hu Danping , Wei Qiujie , Zhang Ying , Guo Yuzhu 
Published: June 2024

Abstract
This study aims to explore the damage behavior of tantalum target plates under high-velocity projectile impact, addressing the threats of damage in the aerospace field due to debris and other factors. With the advent of low-cost space launches and large satellite projects, spacecraft such as space stations are facing increasingly severe collision risks. The research utilizes numerical simulation techniques, based on ANSYS/AUTODYN software and the Smoothed Particle Hydrodynamics (SPH) method, to simulate the impact process of projectiles of different velocities (1 ∼ 10 km/s) and materials (aluminum and steel) on tantalum target plates. The results are intended to provide theoretical support for the design of spacecraft protection structures and contribute data support for establishing a millimeter-level space debris impact database.
Comparison of Drivetrain Vibration Response During Field Operation and on a Nacelle Test Bench
Authors: Siddiqui Muhammad Omer , Eustorgi Karin , Feja Paul 
Published: June 2024

Abstract
Nacelle test benches offer the chance to identify any possible issues in the system design before conducting mandatory field testing for type certification. This can potentially reduce costs and time to market. However, nacelle system testing is an abstraction of the real system, as several interactions and interfaces between the nacelle and its environment are absent. Consequently, this has initiated research studies in recent years to fully understand the influence of these abstractions on the device under test. Extensive research has been conducted on the recently completed project Testfeld BHV to understand the influence of abstractions on the vibration response of the drivetrain. In this project, the Adwen AD8-180 has been the wind turbine under study that was tested first at a nacelle test bench, followed by field tests at a site in Germany. This paper presents the findings of these studies with regards to the drivetrain vibration response during nacelle tests and field tests. The similarities and differences observed in the drivetrain vibration response are highlighted, and reasons that lead to deviations in the vibration response are discussed. Furthermore, the work also presents a simulative framework that can aid the test bench’s ability to predict the correct field-like drivetrain vibration response prior to field tests.
The challenge of cycle-to-cycle variability in dynamic stall modelling
Authors: Damiola Luca , Runacres Mark C. , De Troyer Tim 
Published: June 2024

Abstract
This research explores cycle-to-cycle variability in dynamic stall through wind tunnel experiments conducted on a pitching NACA 0018 aerofoil at a Reynolds number of 2.8×105. Multiple cycles are considered, and different clusters are identified based on inspection of the lift time series. Experiments reveal that the blind application of a conventional phase-averaging approach can produce inadequate results, which do not represent the underlying physics; instead, it is recommended to analyse each cycle individually and use a clustering approach. The available wind tunnel measurements are employed to build two distinct aerodynamic models, i.e. a semi-empirical Goman-Khrabrov dynamic stall model and a purely data-driven model based on artificial neural networks. The work highlights that cycle-to-cycle variability in dynamic stall represents a huge challenge from a modelling perspective. The Goman-Khrabrov model cannot capture the bifurcations in the data, while the more sophisticated data-driven model is accurate but prone to instability. The paper proposes to enhance the accuracy of the models by dynamically assimilating experimental measurements using an Extended Kalman Filter. Results demonstrate that this methodology represents a valuable and versatile tool, which allows to effectively combine imperfect model predictions with experimental observations.
Tuning the Actuator Line Method to Properly Modelling Tip Effects in Finite-Length Blades
Authors: Melani Pier Francesco , Mohamed Omar Sherif , Cioni Stefano , Balduzzi Francesco , Bianchini Alessandro 
Published: June 2024

Abstract
The Actuator Line Method (ALM) is gaining popularity in wind turbine simulations, as it can better handle some of the challenging operating conditions experienced by modern machines, such as highly turbulent inflows, severe aero-elastic forcing, and complex rotor-to-rotor interactions. However, it still falls behind other medium-fidelity methods such as the Lifting Line Free Vortex Wake (LLFVW) when it comes to resolving tip vortices and their effect on the blade spanwise load profile. The reason for such behavior is still unclear. A recent study suggested that this issue can be solved by reducing the scale of the angle of attack (α) sampling and force insertion towards the tip, without the need of additional corrections. This study builds on these findings to further investigate how the ALM base formulation - in terms of α sampling and force insertion - can be tuned to properly describe tip effects. An in-house ALM tool was employed to simulate a finite, constant-chord, NACA0018 wing, for which high-fidelity blade-resolved CFD (BR-CFD) data are available as benchmark. In the first part of the work, different strategies are outlined, including a novel approach for the de-coupling of the angle of attack sampling step from the force projection one, here called DE-coupled LineAverage (DELA). Their accuracy and sensitivity to ALM numerical settings are assessed at a fixed wing pitch angle of 6°. The analysis is then extended to a wider range of blade pitch angles, benchmarking the new ALM formulation against BR-CFD, ALM with the Dağ and Sørensen correction, and LLFVW in terms of blade loads, tip vortex structure, and computational effort.
Potential for large-scale deployment of offshore wind-to-hydrogen systems in the United States
Authors: Brunik K , Thomas J J , Clark C E , Duffy P , Kotarbinski M , Kee J , Grant E , Starke G M , Riccobono N , Koleva M N , Reznicek E P , Barker A , King J 
Published: June 2024

Abstract
This study explores the role of producing low-carbon hydrogen using water electrolysis powered by offshore wind in facilitating the United States’ transition to a net-zero emissions economy by 2050. This research introduces an open-source scenario analysis tool for offshore wind-to-hydrogen systems, aiming to assess the impact of technology, regional considerations, and policy incentives on the cost of producing low-carbon hydrogen through offshore wind. Conducting a regional techno-economic analysis at four U.S. coastal sites, the study evaluates two energy transmission configurations and examines associated costs for the years 2025, 2030, and 2035. The results highlight that locations using fixed-bottom technology may achieve cost-competitive water electrolysis hydrogen production by 2030 through leveraging geologic hydrogen storage and federal policy incentives. Furthermore, floating technology locations are expected to see an average 38% reduction in the levelized cost of hydrogen from 2025 to 2035.
A virtual wind tunnel for deforming airborne wind energy kites
Authors: Wilhelm Poland Jelle Agatho , Schmehl Roland 
Published: June 2024

Abstract
This paper presents a quasi-steady simulation framework for soft-wing kites with suspended control unit employed for airborne wind energy. The kites are subject to actuation-induced and aero-elastic deformation and are described by a coupled aero-structural model in a virtual wind tunnel setup. Key contributions of the present work are a kinetic dynamic relaxation algorithm and a procedure to define a physically consistent initial state. For symmetric actuation, the kite is pitch-statically stable and the simulations converge to a static equilibrium state. Most soft-wing kites are not roll-statically stable and do not find a static equilibrium without a symmetry assumption, as this introduces non-zero roll- and yaw moments. Another important contribution is the introduction of a steady circular flight state that enables convergence without a symmetry assumption. By neglecting gravity, the kite can fly in a perfectly circular turning motion around the wind vector with a constant radius and constant rotational velocity without requiring active control input. In an idealized wind-aligned tether case, the difference in aerodynamic- and centrifugal force application centers makes it impossible to achieve both a force- and moment equilibrium. This was resolved by including an elevation angle that introduces a radial tether force component, which introduces a centrifugal and aerodynamic force difference. Therefore, an operating point with roll equilibrium can be found where the kite finds a static equilibrium, enabling the first quasi-steady simulations of turning flights. Simulated quantifications of soft-wing kite turning behavior, i.e., turning laws, contribute to better kite- and control design.
Lessons learned from the sustainable recycling process of a wind blade made with a new thermoplastic resin
Authors: Carnicero Rafael , Cano Luis , Cruz Ignacio 
Published: June 2024

Abstract
The use of thermoplastic resins instead of thermoset ones in wind turbine blade manufacturing is being investigated and validated in a global scale due to some theoretical improvements such as costs saving during production, shorter cycle’s time and a better circular recovery of the raw materials at the End of Life. The initial objective of this paper was to manufacture and test a small wind turbine blade (SWTB) glass fiber-reinforced thermoplastic (GFRT) resin composites, recycle it, and use the products obtained from the recycling process (fibers and resin) to remanufacture a new thermoplastic SWTB. But loss of fibers higher than estimated during the recycling process made to get away from the original aim of testing both blades (1st and 2nd recyclable blades). At least, some lessons learned were obtained to improve future developments. Nevertheless, this study provides an example of how to recycle a small WT blade and to remanufacture it using the same raw materials.
Numerical study on wake recovery of vertical-axis wind turbines through fixed blade pitch offsets: H vs X rotors
Authors: Ajay Adhyanth Giri , Ferreira Carlos Simao 
Published: June 2024

Abstract
This study assesses the wake recovery mechanism between an H-type Darrieus and an X-type vertical-axis wind turbine, named H-Rotor and X-Rotor respectively for different blade pitch offset configurations. The analysis is conducted in OpenFOAM using the actuator line method to model the turbines to present qualitative (velocity and vorticity contours) and quantitative (available power) studies for three different fixed blade pitch offsets. The results demonstrate that the H-Rotor recovers the wake much faster than the X-Rotor at positive pitch offsets. Overall, applying fixed pitch offsets to VAWT blades helps recover the wake faster than having no blade pitch offset.
Modelling of a Floating-Type Hybrid Wind-Wave System with Oscillating Water Column Wave Energy Converters: A Study Towards Floater Motion Reduction
Authors: Zhu H , Hu C , Yoshida S 
Published: June 2024

Abstract
The integration of floating offshore wind turbines with wave energy converters is regarded as a promising solution for offshore renewable energy development. Given the early stage of wave energy conversion technologies and the substantial influence of control methods on overall system dynamics, a faithful aero-hydro-thermo-elastic-servo-mooring coupled model, along with an engineering environment offering high flexibility for control implementations, is essential. To address the requirement, a numerical modeling framework is developed in this study based on Simulink, known for its superiority in control design and implementation, and OpenFAST, which offers a reliable floating wind turbine model. The model incorporates the thermodynamics of the air in chambers, power take-off dynamics, and oscillating water column dynamics. Furthermore, bypass valves are utilized for the wave energy converters to adjust chamber pressure and reduce floater motion, with a control law proposed to regulate the valve opening ratio. A case study is conducted under harsh ocean conditions to validate the model. The numerical results not only demonstrate the feasibility of the model but also underscore the effectiveness of the control law in improving floater motion performance.
A reduced order/simplified method for uncertainty quantification on the floating wind turbine design basis
Authors: Yildirim B , Dimitrov N , Abrahamsen A B , Kolios A 
Published: June 2024

Abstract
The cost of floating wind turbines (FWTs) is currently higher than onshore and bottom fixed offshore wind turbines. An important step towards more cost-efficient FWT structures is understanding the uncertainties and how they affect the design performance. On the path towards developing a fully probabilistic design approach, an important initial step is defining the variables and uncertainties that significantly impact the final design performance. This study aims to conduct a design sensitivity analysis on a FWT system consisting of the VolturnUS Semisubmersible floater coupled with an IEA 15 MW turbine. First, a Python-based design evaluation framework is implemented that computes operational limit states as a function of design input parameters defining the floater design. The system responses and the loads are obtained using Horizontal Axis Wind turbine simulation Code 2nd generation (HAWC2). Time domain outputs of the design evaluation framework are compared to a frequency domain response using Quick Load Analysis of Floating Wind Turbines (QuLAF). Initial results provide that buoyancy column diameter and the floater radius have the highest effects on the general floater response.
Exploring the Interdependence of Vertical Extrapolation Uncertainties in Repowering Wind Farms
Authors: Mazoyer P , Duc T , Bechmann A , Kariniotakis G 
Published: June 2024

Abstract
Assessing a wind farm’s annual energy production (AEP) involves modelling the wind resource and the wind-to-power conversion at the site. The greenfield pre-construction phase generally comprises the installation of wind measurement devices. For repowering projects, the wind data from the pre-construction phase of the existing farm can be used as wind input to assess the energy yield of the repowered wind farm. Indeed, one study demonstrates that when the modelling error correlations are known, the AEP prediction uncertainty of the repowered farm can be reduced by combining the energy production records of the existing farm with the AEP assessment for both farms. Previous studies have successfully identified the correlation structure for certain errors, especially for horizontal flow modelling, but not for vertical flow modelling. However, vertical extrapolation is essential, as the wind measurement heights are generally lower than the hub height on the repowered farm. This paper bridges this research gap and demonstrates that the correlation structure of errors in vertical profile modelling is Gaussian, with parameters dependent on shear values and heights. The distribution is validated against site data from simple to moderately complex sites in France.
A critical insight into the most effective CFD settings to model atmospheric stability in wind energy applications
Authors: Travaglini Riccardo , Melani Pier Francesco , Balduzzi Francesco , Orlando Stephen , Viti Valerio , Bianchini Alessandro 
Published: June 2024

Abstract
An accurate reconstruction of the Atmospheric Boundary Layer (ABL) is key for the estimation of energy production and loads in modern wind turbines since, at current rotor heights, the vertical structure of the ABL is heavily influenced by thermal stratification effects. The wind power community usually accounts for these effects by semi-empirical modifications to the neutral ABL profile obtained using linear solvers such as WAsP; this approach, however, may not be suitable for sites with complex terrain, time-dependent thermal effects, or dense canopies. In these applications, methods with higher fidelity, such as Computational Fluid Dynamics (CFD) approaches based on steady or unsteady Reynolds Averaged Navier-Stokes (RANS) equations are needed. While CFD is recognized as providing more accurate results for these realistic cases, its use is still not a common best practice. In the current study, the WindModeller CFD tool by Ansys was employed to assess the effect of various inlet boundary conditions on the predicted wind speed profiles in unstable and stable atmospheric conditions. The test case is a wind farm in North Dakota, USA, characterized by a simple terrain but strong atmospheric stability effects and temperature fluctuations. The comparison of CFD results with experimental measurements and WAsP-CFD simulations reveals a high level of agreement between CFD and experimental data in stable conditions. In the case of unstable conditions, despite the good representation of the wind field, a high sensitivity to inlet boundary conditions is highlighted.
An improved statistical wake meandering model
Authors: Brugger Peter , Markfort Corey , Porté-Agel Fernando 
Published: June 2024

Abstract
A new statistical wake meandering (SWM) model is proposed that improves on existing models in the literature. Compared to the existing SWM models, the proposed model has a closed description that does not require simulations to create look-up tables while maintaining applicability to a wide range of flow conditions. The proposed SWM model is compared to the predictions of the Dynamic Wake Meandering (DWM) model and to wind speed measurements from a scanning Doppler lidar mounted on the nacelle of a utility-scale wind turbine for validation. The results show that the proposed model has a similar performance as the DWM model for the effect of wake meandering on the mean velocity deficit and the turbulence intensity, while being significantly faster to compute.
Site-specific production forecast through data-driven and engineering models
Authors: Braunbehrens R , Strecker K , Anand A , Felder M , Petzschmann J , Bottasso C L 
Published: June 2024

AbstractThe present study investigates the predictive capabilities of two site-specific wind power forecasting models. The two approaches make use of a machine learning ensemble model that combines forecasts from several numerical weather predictions (NWP) to match local observations. In the first approach, the training data consists of historical site power production recordings. This yields a black-box model that includes the wind farm behaviour. The second approach is a combination of data-driven and explicit modelling. In the first step, the machine learning ensemble model forecasts the site wind conditions. Then, this input is fed to a site-specific engineering wake model. This hybrid ”grey-box” approach explicitly resolves some farm flow effects.The study shows that the performance of both methods differs over the wind speed range. The purely data-driven model performs better at medium wind speeds, which also occur more often. The hybrid method predictions agree better during periods of higher wind speeds. In the last part, the study showcases the capabilities of the forecasting methods when participating in the energy market. Additionally, the engineering wake model allows for power maximisation through wind farm control.
Floating wind farm design using social and environmental constraints
Authors: Yilmazlar Kutay , White Craig , Cacciola Stefano , Cândido José , Croce Alessandro 
Published: June 2024

Abstract
This work proposes a wind farm design methodology, integrating several design variables from different design aspects into an optimization problem, such as turbine power, number of turbines, cable types, wind farm layout and site location. A mixed integer genetic algorithm is employed to combine discrete and continuous design variables to find the design with minimum Levelized Cost of Energy (LCoE). The wind farm LCoE is calculated using a wind farm model, which combines detailed cost functions for different cost elements and engineering wake models to estimate Annual Energy Production. The design is constrained not only by technical aspects such as total power, farm area, but also by environmental and social constraints. These include the wind farm visibility, which is a popular concern among the people living along the coast of nearby wind farms, and availability, implying the compliance with the designated exclusion zones. To demonstrate the sensitivity of design constraints, two floating wind farms are sited and optimized as a case study, using different visibility constraints. The developed design tool within this study aims to bridge the gap between wind farm developers and local authorities who are responsible for permitting and zoning of development areas.
Characterisation and Integration of Piezoelectric Trimorph Actuators for Blade Active Surface Control on a Scaled Wind Turbine
Authors: Fuentes Holden J P , Gan L , Sims-Williams D , Gilbert J , Osborne P , Bastankhah M 
Published: June 2024

Abstract
The paper investigates the integration of piezoelectric bending actuators on trailing edge flaps (TEF). The characterisation of piezoelectric actuators is of great importance due to differences in performance resulting from sample variability, actuator construction, circuit type and equipment. For the application of trailing edge flaps in scaled turbines, the total deflection these actuators can produce determines the possible flap angles and, consequently, the potential effects on wake evolution downwind of the wind turbine. In this paper, we fully characterise the performance of the piezoelectric bending actuator under a variety of operating conditions. The bridged bi-polar circuit is used to drive the piezoelectric actuators with both a static and a dynamic signal. Deflection results demonstrate that the piezoelectric actuator is capable of achieving flap angles of β ± 3° with a static signal, and β = 2.3° and β = −3.2° angles with a dynamic signal. Experimental force measurements using a dynamic signal result in a force reduction of up to 33% when compared to a static signal. Force values at increasing frequencies do not show a depreciation in force. Additionally, initial aerodynamic loads exerted on TEF are presented based on XFoil simulations to ensure that the piezoelectric actuating force can overcome aerodynamic loads for future experiments. Experimental force measurements from the piezoelectric actuator demonstrate that aerodynamic forces can be overcome. This work serves as the first step towards implementing the TEF technology in lab-scaled wind turbine models.