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The design of wind turbines has been continually evolving to enhance aerodynamic efficiency, which is crucial for improving energy conversion and reducing operational costs. One promising technique is the application of the Co-Flow Jet (CFJ) method, which utilizes simultaneous blowing and suction to augment aerofoil performance. Despite its potential benefits, the relationship between aerofoil thickness and the resulting improvements in lift and drag coefficients has not been thoroughly explored, especially for the National Renewable Energy Laboratory (NREL) aerofoils commonly used in wind turbine applications. This study utilizes computational fluid dynamics (CFD) simulations in order to investigate the aerodynamic efficiency improvements of the NREL S826, NREL S825, and NREL S818 aerofoils through the application of the CFJ technique. Various configurations with different blowing (B) and suction (S) configurations were tested, including 0.08B-0.7S, 0.08B-0.8S, 0.1B-0.7S, and 0.2B-0.7S configurations. The results demonstrate that the S826-0.2B-0.7S, S825-0.2B-0.7S, and S818-0.08B-0.7S configurations yield the most significant enhancements at a common momentum coefficient (Cm) of 0.08. Specifically, there were increases in lift coefficients by about 51.1%, 66.38%, and 109%, and improvements in lift-to-drag ratios by about 11.5%, 14.38%, and 146.18% for the S826-0.2B-0.7S, S825-0.2B-0.7S and S818- 0.08B-0.7S configurations, respectively. [ABSTRACT FROM AUTHOR]

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[Display omitted] • Swelling-assisted pyrolysis was proposed for the recovery of glass fibers from WTBs. • Resin decomposition ratio reached 76.8 % at 350 °C in swelling-assisted pyrolysis. • The swelling treatment physically disrupted the cross-linked structure of the WTBs. • The oxidation duration was reduced owing to the less content of pyrolysis char. • Tensile strength of fibers from swollen-WTB was higher than that from original-WTB. The recycling of end-of-life wind turbine blades has become a global environmental challenge driven by the rapid growth of wind power. Pyrolysis is a promising method for recovering glass fibers from these discarded blades, but traditional pyrolysis is often operated at high temperatures, which degrades the mechanical properties of recovered fibers. To address this issue, a swelling-assisted pyrolysis method was proposed to recover high-quality glass fibers from end-of-life wind turbine blades at low temperatures. The results confirmed that the decomposition of the resin matrix within the blade was significantly promoted at low temperatures in the swelling-assisted pyrolysis process, achieving a resin decomposition ratio of 76.8 % at 350 °C. This improvement was attributed to enhanced heat transfer and co-pyrolysis with acetic acid. Swelling could physically disrupt the cross-linked structure of the blade, creating a more porous and layered structure, thereby enhancing heat transfer during the pyrolysis process. Simultaneously, the co-pyrolysis with acetic acid could generate hydrogen radicals, which promoted the cracking of macromolecular oligomers into lighter products or gaseous alkanes. Consequently, the formation of pyrolysis char within the solid pyrolysis product was reduced, shortening the oxidation duration to 30 min. In comparison to traditional pyrolysis, the swelling-assisted pyrolysis process effectively suppressed the diffusion of surface defects over the recovered fibers, leading to promising improvements in their flexibility, elasticity, and mechanical properties, with tensile strength notably increased by 27.5 %. These findings provided valuable insights into recovering high-quality glass fibers from end-of-life wind turbine blades. [ABSTRACT FROM AUTHOR]

The wind energy sector is experiencing rapid growth, marked by the expansion of wind farms and the development of large-scale turbines. However, conventional manual methods for wind turbine operations and maintenance are struggling to keep pace with this development, encountering challenges related to quality, efficiency, and safety. In response, unmanned aerial vehicles (UAVs) have emerged as a promising technology offering capabilities to effectively and economically perform these tasks. This paper provides a review of state-of-the-art research and applications of UAVs in wind turbine blade damage detection, operations, and maintenance. It encompasses various topics, such as optical and thermal UAV image-based inspections, integration with robots or embedded systems for damage detection, and the design of autonomous UAV flight planning. By synthesizing existing knowledge and identifying key areas for future research, this review aims to contribute insights for advancing the digitalization and intelligence of wind energy operations. [ABSTRACT FROM AUTHOR]

The wind energy sector faces a persistent challenge in developing sustainable solutions for decommissioned Wind Turbine Blades (WTB). This study utilises Lifecycle Assessment (LCA) to evaluate the gate-to-gate carbon footprint of high-profile disposal and recycling methods, aiming to determine optimal strategies for WTB waste treatment in the UK. While this article analyses the UK as a case study, the findings are applicable to, and intended to inform, recycling strategies for WTB waste globally. Long-term sustainability depends heavily on factors like evolving energy grids and changing WTB waste compositions and these must be considered for robust analysis and development strategy recommendations. In the short to medium term, mechanical recycling of mixed WTB waste is sufficient to minimise Global Warming Potential (GWP) due to the scarcity of carbon fibre in WTB waste streams. Beyond 2040, carbon fibre recycling becomes crucial to reduce GWP. The study emphasises the importance of matching WTB sub-structure material compositions with preferred waste treatment options for the lowest overall impact. Future development should focus on the extraction of carbon fibre reinforced polymer (CFRP) structures in WTB waste streams, commercialising large-scale CFRP structure recycling technologies, establishing supply chains, and validating market routes for secondary carbon fibre products. In parallel, scaling up low-impact options, like mechanical recycling, is vital to minimise WTB waste landfilling. Developing viable applications and cost-effective market routes for mechanical recyclates is necessary to displace virgin glass fibres, while optimising upstream recycling processes based on product requirements. [ABSTRACT FROM AUTHOR]

INTRODUCTION: As a renewable and clean use of energy, wind power generation has a very important role in the new energy generation industry. For the many parts of various wind turbines, the safety and reliability of wind turbine blades are very important. OBJECTIVES: The energy spectrum simulation algorithm included in the wavelet analysis method is used to simulate and analyzewind turbine blade damage, to verify the correctness and validity of wind turbine blade damage analysis. METHODS: Matlab simulation is used to introduce the experiments related to the static and dynamic detection of fiber grating sensors, analyze the signal characteristics of the wind turbine blade when it is damaged by the impact, and provide a basis for the analysis of the external damage of large wind turbine blade. RESULTS: The main results obtained in this paper are the following. By analyzing the decomposition of wavelet packets, the gradient change of wavelet impact energy spectrum before and after the wavelet damage was obtained and compared with the histogram, and the impact energy spectrum of each three-dimensional wavelet energy packet in the image was compared and analyzed, which can well realize the recognition of wavelet damage gradient for solid composite materials. CONCLUSION: With the help of Matlab simulation to collect the impact response signal, using the wavelet packet energy spectrum method to analyze the signal, can derive the characteristics of wind turbine blade damage. [ABSTRACT FROM AUTHOR]

Wind energy is an important clean energy, according to China's carbon peak and carbon neutral strategy, the policy of replacing small with large wind turbine blades and replacing old with new is imperative. The main material of wind turbine blades is glass fiber reinforced polymer, which has problems of difficult recycling technology and high recycling cost. Nowadays, there is no ideal large-scale recycling method. Therefore, the systematic and high-value utilization of waste wind turbine blades is imminent. In this paper, the material type, recycling methods and their respective characteristics of wind turbine blades are summarized. The recent developments of waste wind turbine blades in cement-based materials and thermoplastic polymer materials are thoroughly discussed. Overall, this paper can provide reference for the subsequent development and research on the recycling waste wind turbine blades. [ABSTRACT FROM AUTHOR]

In this paper, a new concept of extra-durable and sustainable wind turbine blades is presented. The two critical materials science challenges of the development of wind energy now are the necessity to prevent the degradation of wind turbine blades for several decades, and, on the other side, to provide a solution for the recyclability and sustainability of blades. In preliminary studies by DTU Wind, it was demonstrated that practically all typical wind turbine blade degradation mechanisms (e.g., coating detachment, buckling, spar cap/shell adhesive joint degradation, trailing edge failure, etc.) have their roots in interface degradation. The concept presented in this work includes the development of bio-inspired dual-mechanism-based interface adhesives (combining mechanical interlocking of fibers and chemical adhesion), which ensures, on the one side, extra-strong attachment during the operation time, and on the other side, possible adhesive joint separation for re-use of the blade parts. The general approach and physical mechanisms of adhesive strengthening and separation are described. [ABSTRACT FROM AUTHOR]

To alleviate the environmental pollution caused by waste wind turbine blades and provide new ideas for recycling, the thermochemical characteristics of four basic components of composite materials commonly used in wind turbine blades were studied in this paper. Thermogravimetric experiments in different atmospheres and heating rates, and thermogravimetric‐infrared combined experiments were carried out. The results show that the reaction of epoxy resin and thermoplastic polyurethane was easy and deep in N2 and CO2. Except for glass fiber, the other three components showed different combustion characteristics in air. The maximum reaction rates and activation energy of resin‐based components in N2 increased with increasing heating rate. The pyrolysis products of the four basic components all contained CO2 and CO, and some aromatic substances could be generated during the thermal transformation of epoxy resin and thermoplastic polyurethane. It can be concluded that the thermal transformation properties of the basic components of the composite material of wind turbine blades can be used to treat the waste blades, making the resin as the matrix material undergo a thermal transformation reaction and recover the fiber. This is to effectively guarantee the green and sustainable development of wind power generation. [ABSTRACT FROM AUTHOR]

This paper examines the potential for reducing the cost of energy for super-scale wind turbines through the use of a downwind configuration. Using nonlinear aeroelastic modeling, the responses of 10 MW upwind and downwind wind turbine blades are simulated and compared under shear wind conditions. The study evaluates the impact of both nonlinear and linear aeroelastic models on the dynamic response of different blade sizes, highlighting the need for a nonlinear approach. Results indicate that the linear model overestimates blade deformations (18.14%) and the nonlinear model is more accurate for predicting the aeroelastic response of ultra-long blades of 86.35 m. The study also finds that the downwind turbine blade experiences smaller flapwise moment (17.53%), and blade tip flapwise deformation (33.97%) than the upwind turbine blade, with increased load and deformation fluctuation as wind shear increases. [ABSTRACT FROM AUTHOR]

Copyright of Acta Materiae Compositae Sinica is the property of Acta Materiea Compositae Sinica Editorial Department and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Wind energy is considered a clean energy source and is predicted to be one of the primary sources of electricity. However, leading-edge erosion of wind turbine blades due to impacts from rain drops, solid particles, hailstones, bird fouling, ice, etc., is a major concern for the wind energy sector that reduces annual energy production. Therefore, leading-edge protection of turbine blades has been an important topic of research and development in the last 20 years. Further, there are critical issues related to the amount of waste produced, including glass fiber, carbon fiber, and various harmful volatile organic compounds in turbine fabrication and their end-of-life phases. Hence, it is vital to use eco-friendly, solvent-free materials and to extend blade life to make wind energy a perfect clean energy source. In this study, cellulose microparticles (CMP) and cellulose microfibers (CMF) have been used as fillers to reinforce water-based polyurethane (PU) coatings developed on glass fiber reinforced polymer (GFRP) substrates by a simple spray method for the first time. Field emission scanning electron microscopy images show the agglomerated particles of CMP and fiber-like morphology of CMF. Fourier transform infrared spectra of CMP, CMF, and related coatings exhibit associated C–H, C=O, and N–H absorption bands of cellulose and polyurethane. Thermal gravimetric analysis shows that CMP is stable up to 285 °C, whereas CMF degradation is observed at 243 °C. X-ray photoelectron spectroscopy of C 1s and O 1s core levels of CMP, CMF and related coatings show C–C/C–H, C–O, C–OH, and O–C=O bonds associated with cellulose structure. The solid particle erosion resistance properties of the coatings have been evaluated with different concentrations of CMP and CMF at impact angles of 30° and 90°, and all of the coatings are observed to outperform the PU and bare GFRP substrates. Three-dimensional (3D) profiles of erosion scans confirm the shape of erosion scars, and 2D profiles have been used to calculate volume loss due to erosion. CMP-reinforced PU coating with 5 wt.% filler concentration and CMF-reinforced PU coating with 2 wt.% concentration are found to be the best-performing coatings against solid particle erosion. Nanoindentation studies have been performed to establish a relation between H3/E2 and the average erosion rate of the coatings. [ABSTRACT FROM AUTHOR]

Wind energy has been regarded to be one of the renewable energies to rely on for the future. In tropical countries like India maintenance of wind turbine blades is a challenging task. Solid particle erosion is one of the root causes of wind turbine blade damage resulting in reduction in energy production. In the present study, in-house synthesized ceramic oxide nanoparticles such as Al 2 O 3 , ZrO 2 , and CeO 2 are used as fillers for reinforcement of water-based polyurethane (PU) coatings on glass fibre reinforced polymer (GFRP) substrates for solid particle erosion resistance for the first time. Al 2 O 3 , ZrO 2 , and CeO 2 nanoparticles have been prepared by solution combustion synthesis method using urea, glycine, and oxalyl dihydrazide, respectively, as fuels. These ceramic nanoparticles are found to crystallize in corundum, tetragonal, and cubic structures, respectively, as confirmed by X-ray diffraction studies. Field emission scanning electron microscopy shows the porous microstructure of the oxide products due to the release of gases in course of preparation. Transmission electron microscopy studies of these nanoparticles show corresponding lattice fringes in their high-resolution images. Observed Al–O, Zr–O, and Ce–O vibrational modes in Raman spectra confirm the formation of corresponding oxides. The oxidation states of Al, Zr, and Ce in the respective oxides are found to be +3, +4, and +4, respectively, as demonstrated by X-ray photoelectron spectroscopy. The nanocomposite coatings consisting of PU and Al 2 O 3 , ZrO 2 , and CeO 2 nanoparticles have been developed by a simple spray method on GFRP substrates. The solid particle erosion resistance tests of coatings have been studied at varied concentrations of Al 2 O 3 , ZrO 2 , and CeO 2 nanoparticles at impinging angles of 30° and 90°. It has been observed that ZrO 2 , and CeO 2 nanoparticles-reinforced PU coatings show better solid particle erosion resistance compared to Al 2 O 3 -reinforced coating. Among different concentrations studied here, coatings with 15 wt% filler concentrations offer a relatively low erosion rate than the other concentrations at both impinging angles. However, GFRP substrate and PU coating are observed to show much higher erosion rate compared to nanoparticles reinforced PU coatings. [ABSTRACT FROM AUTHOR]

Wind turbines obtain clean energy from the wind, however, there is a significant environmental impact due to the use of some of their materials. This article analyzes the manufacturing, life cycle, and dismantling of these machines, to under-stand new opportunities to improve these negative aspects, through the review of various articles. The search was focused on SCOPUS articles, using the word "wind turbine" in titles, abstracts, and keywords, obtaining 68,362 results. Subsequently, these results were filtered only articles, reviews, and research theses, reducing the search to 3,663 results, the search was limited to only 10 years, counting from 2020 to 2010, reaching 2,189 documents. The analysis of 2,189 documents obtained is carried out, reducing the literary base to 185 documents with information on manufacturing processes, life cycle analysis, and advances in some countries in the implementation of improvements in the manufacture of wind turbines, to reduce environmental impact. The use of thermosetting materials in wind turbine blades is a reality that must be modified by the environmental problems that these are causing, new materials for blades must be developed by the principles of the circular economy. [ABSTRACT FROM AUTHOR]

When designing a wind turbine, the main objective is to generate maximum effective power with the lowest possible production costs. The power of a wind turbine depends primarily on the aerodynamic properties of its blades. Moreover, the cost of making a blade for a wind turbine, and therefore also for the entire wind turbine, depends on the materials used for its production. Therefore, wind turbine blades are the most studied element of a wind turbine. By selecting the optimal material and geometric properties of the wind turbine blade, it is possible to reduce the costs of making the entire wind turbine. These rationales led the authors to investigate composite wind turbine blades. A two-criteria optimization task was formulated, which allowed for the simultaneous consideration of two criteria: minimizing the mass and minimizing the vertical deflection of the wind turbine blade. Geometric properties of the blade, influencing the considered criteria, were assumed as decision variables. The weighted sum method was used. The results obtained allowed us to determine the optimal geometric and material properties of a wind turbine blade. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Harbin Institute of Technology. Social Sciences Edition / Haerbin Gongye Daxue Xuebao. Shehui Kexue Ban is the property of Harbin Institute of Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Wind turbine blades are critical components in wind energy generation, and blade health management is a challenging issue for the operation and maintenance of wind turbines. In this paper, an adaptive method is developed to identify blade damages based on the microphone array and compressive beamforming, and global and remote health assessment can be accomplished. In this method, the generalized minimax-concave penalty function is employed to enhance sparse recovery capacities, and step-sizes in computation processes are adjusted adaptively to adapt to variational conditions. Besides, potential damage locations are extracted in coarse acoustic maps to improve convergence rates. Numerical simulations show that high spatial resolutions can be achieved by the proposed method, and the computation time for solving acoustic inverse problems is less than using existing algorithms, especially with low-frequency sources. Moreover, experiments are conducted with a small-scale wind turbine. Results demonstrate that several damages in operating blades can be precisely recognized with high efficiencies, and the deterioration of acoustic maps induced by improper step-sizes can be avoided. The proposed method provides a promising way for in-situ health monitoring of wind turbine blades. [Display omitted] • An adaptive method for compressive beamforming is proposed to examine blade damages. • The generalized minimax-concave penalty function is utilized in the method. • Step-sizes in iterations are adjusted adaptively to adapt to variational conditions. • Special initial solutions are arranged based on potential damage locations. • Experimental validations are conducted with a small-scale wind turbine. [ABSTRACT FROM AUTHOR]

Nigeria can reduce its level of dependency on fossil fuel by making use of wind energy which is an indigenous renewable energy source for electricity generation. For large energy generation, large wind turbine is more preferable over a wind farm of smaller wind turbine units that will generate the equivalent amount of energy because, there will be loss of energy due to transmission and generation system of every turbine unit of the wind farm while the larger turbine has only one transmission and generation units. However, smaller wind turbines are generally more efficient than the bigger ones in terms of wind energy conversion and they are therefore good for small power generation. In this research work the performance of two different sizes of small wind turbine rotors, a 4-metre rotor (D4-Rotor) and a 4/5-metre one (D4/5-Rotor) were studied at 6m/s wind speed using numerical method. The POINTWISE software is used for modelling the rotor blade and meshing the flow domain. The software used for the simulation is ANSYS 20 which uses finite volume method (FVM) of analysis for solving governing flow equations. From the result of performances, the D4/5-Rotor has higher power coefficient (0.2995) than that of D4-Rotor (0.237), and this indicate about 26 per cent performance improvement of the smaller rotor. Conclusively, smaller wind turbines are more efficient than the bigger ones in terms of wind energy conversion and they are therefore good for small power generation especially in low wind regime. [ABSTRACT FROM AUTHOR]

For investigation of the effects of turbulence intensity (TI) on the wind loads on wind turbine blade, a 1:20 scaled model of a typical 3D wind turbine blade is designed and used for the pressure measurement test in a wind tunnel. Five uniform flows with different turbulence intensities are simulated in the wind tunnel test. The mean and root-mean-square (RMS) wind pressure coefficients, base moment coefficients, and their power spectral densities are presented and discussed in detail. Combined with the dynamic properties of the blade structure, wind-induced displacements at the tip of the blade are calculated by the random vibration theory. The results show that the increasing of TI amplifies the aerodynamic loads on the blade in terms of RMS wind pressure coefficients and RMS bending moment coefficients. Large wind-induced displacement of the wind turbine blade may be stimulated by high TI even under the feathering condition. This article aims to further the understanding of wind loads on wind turbine blades and provide useful information for the wind-resistant design of wind farms established in regions with high turbulence levels. [ABSTRACT FROM AUTHOR]

Rain-induced leading-edge erosion of wind turbine blades is associated with high repair and maintenance costs. For efficient operation and maintenance, erosion models are required that provide estimates of blade coating lifetime at a real scale. In this study, a statistical rainfall model is established that describes probabilistic distributions of rain parameters that are critical for site-specific leading-edge erosion assessment. A new droplet size distribution (DSD) is determined based on two years' onshore rainfall data of an inland site in the Netherlands and the obtained DSD is compared with those from the literature. Joint probability distribution functions of rain intensities and droplet sizes are also established for this site as well as for a coastal site in the Netherlands. Then, the application of the proposed model is presented for a 5 MW wind turbine, where the model is combined with wind statistics along with an analytical surface fatigue model that describes lab-scale coating degradation. The expected lifetime of the blade coating is found three to four times less for the wind turbine operating at the coastal site than for the inland site - primarily due to rainfall at higher wind speeds. Further, the robustness of the proposed model is found consistent with varying data periods used for the analyses. [ABSTRACT FROM AUTHOR]

Purpose: The main goal of this work is to evaluate the environmental impact of a 63-m blade for wind generators. The embodied energy and the carbon footprint are used as supporting tools for material selection in the initial project stages. Methods: Real industrial data regarding the most used materials for wind turbine blade construction are used. Two eco-parameters, embodied energy and carbon footprint, were calculated from each selected material together with values of manufacture, transport, use, and final disposal. The blades must be built to have a mechanical strength high enough to withstand vibrations caused by manufacturing flaws, turbulence, or irregular loading. In this sense, Young's modulus, yield strength, and density were compared to the environmental footprint data to support the final material choice. This evaluation process of the possible materials to be used in the blade manufacture was carried out in the initial stages of the project. Results: Composite materials such as glass fiber-reinforced polymer (GFRP) and carbon fiber-reinforced polymer (CFRP), bonded together with an adhesive material, are used to build modern wind turbine blades. Those composites comprise a considerable number of different materials that can be mixed to reach adequate performance. Comparisons were made with 46 pre-selected materials, considering the mechanical behavior and environmental impacts. The final selected materials have better properties than the reference material. Finally, two materials with the desired mechanical properties and with a potential lower negative environmental impact than the reference material were selected. Conclusions: Replacing the reference resin—epoxy/E-glass fiber—with the epoxy resin with the lowest environmental impact—epoxy/S-glass fiber—will reduce the total value of the environmental load to 102 GJ of energy and 3.4 t of CO2. As important as the material selection in the early stages of product development is the end of life (EoL) choice. In this case, the glass fiber has an EoL potential of 370 GJ of energy and 460 t of CO2 in the remanufacturing option, against zero for the landfill. This work shows that carefully selected raw materials and EoL alternatives for WTB can significantly reduce the environmental impact of this component. [ABSTRACT FROM AUTHOR]

Wind energy, with an exponential growth in the last years, is nowadays one of the most important renewable energy sources. Modern wind turbines are bigger and complex to produce more energy. This industry requires to reduce its operating and maintenance costs and to increase its reliability, safety, maintainability and availability. Condition monitoring systems are beginning to be employed for this purpose. They must be reliable and cost-effective to reduce the long periods of downtimes and high maintenance costs, and to avoid catastrophic scenarios caused by undetected failures. This paper presents a survey about the most important and updated condition monitoring techniques based on non-destructive testing and methods applied to wind turbine blades. In addition, it analyses the future trends and challenges of structural health monitoring systems in wind turbine blades. • A Survey Non-Destructive Testing in Wind Turbine Blades (WTB). • Most important and updated condition monitoring techniques and methods applied to WTB. • Analysis the future trends and challenges of structural health monitoring systems in WTB. • Condition monitoring systems to reliability, safety, maintainability and availability of WTB. [ABSTRACT FROM AUTHOR]

Wind energy is one among the most promising renewable energy sources, and hence there is fast growth of wind energy farm implantation over the last decade, which is expected to be even faster in the coming years. Wind turbine blades are complex structures considering the different scientific fields involved in their study. Indeed, the study of blade performance involves fluid mechanics (aerodynamic study), solids mechanics (the nature of materials, the type of solicitations ...), and the fluid coupling structure (IFS). The scope of the present work is to investigate the mechanical performances and structural integrity of a large offshore wind turbine blade under critical loads using blade element momentum. The resulting pressure was applied to the blade by the use of a user subroutine "DLOAD" implemented in ABAQUS finite element analysis software. The main objective is to identify and predict the zones which are sensitive to damage and failure as well as to evaluate the potential of composite materials (carbon fiber and glass fiber) and their effect on reduction of rotor's weight, as well as the increase of resistance to wear, and stiffness. [ABSTRACT FROM AUTHOR]

To achieve the goal of carbon neutrality and peak carbon dioxide emissions, and reduce the development and utilization of fossil energy, wind power, as a typical clean energy source, has the advantages of wide distribution, environmental protection and remarkable scale benefits. However, wind turbines installed in cold regions or high-altitude areas often encounter an icing climate during winter operations, which affects the economic benefits and stability of wind power plants. To address the above issues, research has been carried out in recent years on coating with superhydrophobic anti-icing properties. In this review, the theory of solid surface wettability was described, and the mechanism and hazards of wind turbine blade icing were introduced. The preparation methods of superhydrophobic ice-phobic coating were systematically summarized, and the advantages and disadvantages of different methods were discussed based on the current research. To make the superhydrophobic ice-phobic coating have excellent weather resistance in the actual operation of wind turbine blades, a method of adding self-cleaning, anti-corrosion, photothermal conversion and other functions to the original coating was proposed. In addition, the application of superhydrophobic ice-phobic coating in transmission lines, aircraft wings and other fields was briefly described, which provided references for anti-icing research in different industries. [Display omitted] • The wind turbine blade icing mechanism and ice-phobic coating technology were reviewed. • Different methods for the preparation of ice-phobic coating were summarized. • The ice-phobic coating with self-cleaning, anti-corrosion and photothermal properties was introduced. • The existing problems of coating were analyzed and future direction was discussed. [ABSTRACT FROM AUTHOR]

Wind turbine energy minimizes due to vibration of blade. In this research we focus on vibration suppression by using particle damping technique. Containers are used for fill the particles and mounted on the blade. As vibration of blade increases, it increases the movement of containers along with particles this brings particle to particle and particle to container wall collision takes place which results to energy loss. In this study we use four different positions for mounting containers, firstly on all four different positions we mount containers simultaneously and take three readings for three different ball sizes respectively, keeping 50% fill constant in all readings. Then we reduce one container among four and take the readings. Repeat this procedure up to single container. Compare with damping results with without damping results and finding out optimum locations for mounting of dampers. [ABSTRACT FROM AUTHOR]

Abstract With the growing shortage of energy, wind power is receiving an increasing amount of attention worldwide as a clean source of renewable energy. One of the most important components of the wind turbine is the bird-wing-like blade under the working principle. Three kinds of bionic blades are designed by using bionic wing type and configuration based on the good aerodynamic performance of seagull wings, combined with the theory of wind turbine blade design-the blade element theory. Standard blade and aerodynamic performances of bionic blade are evaluated by means of numerical simulation. Under different wind speeds, the results show that the blade torque of the bionic blade of total improved airfoil increases by 10.2%, the bionic blade of partially improved airfoil increases by 14%, and the configuration improved blade increases by 7%. To verify the correctness of the numerical simulation results, we run the bionic blade and establish a corresponding experimental device in an actual experiment. The results of the experiment are consistent with the trend of the numerical simulation. [ABSTRACT FROM AUTHOR]

It is common to dissociate load computation from structural analysis when carrying out a numerical assessment of a wind turbine blade. Loads are usually computed using a multiphysics and multibody beam finite element model of the whole turbine, whereas detailed structural analysis is managed using shell finite element models. This raises the issue of the application of the loads extracted from the beam finite element model at one node for each section and transposed into the shell finite element model. After presenting the methods found in the literature, a new method is proposed. This takes into account the physical consistency of loads: aerodynamic loads are applied as pressure on the blade surface, and inertial loads are applied as body loads. Corrections imposed by pressure and body load computation in order to match loads from the beam finite element model are proposed and a comparison with two other methods is discussed. [ABSTRACT FROM AUTHOR]

This paper describes the feasibility analysis of an innovative, extensible blade technology. The blade aims to significantly improve the energy production of a wind turbine, particularly at locations with unfavorable wind conditions. The innovative 'smart' blade will be extended at low wind speed to harvest more wind energy; on the other hand, it will be retracted to its original shape when the wind speed is above the rated wind speed to protect the blade from damages by high wind loads. An established aerodynamic model is implemented in this paper to evaluate and compare the power output of extensible blades versus a baseline conventional blade. The model was first validated with a monitored power production curve based on the wind energy production data of a conventional turbine blade, which is subsequently used to estimate the power production curve of extended blades. The load-on-blade structures are incorporated as the mechanical criteria to design the extension strategies. Wind speed monitoring data at three different onshore and offshore sites around Lake Erie are used to predict the annual wind energy output with different blades. The effects of extension on the dynamic characteristics of blade are analyzed. The results show that the extensive blade significantly increases the annual wind energy production (up to 20% to 30%) with different blade extension strategies. It, therefore, has the potential to significantly boost wind energy production for utility-scale wind turbines located at sites with low-class wind resource. [ABSTRACT FROM AUTHOR]

Wind blades are major structural elements of wind turbines, but they are prone to damage like any other composite component. Blade damage can cause sudden structural failure and the associated costs to repair them are high. Therefore, it is important to identify the causation of damage to prevent defects during the manufacturing phase, transportation, and in operation. Generally, damage in wind blades can arise due to manufacturing defects, precipitation and debris, water ingress, variable loading due to wind, operational errors, lightning strikes, and fire. Early detection and mitigation techniques are required to avoid or reduce damage in costly wind turbine blades. This article provides an extensive review of viable solutions and approaches for damage mitigation in wind turbine blades. [ABSTRACT FROM AUTHOR]

Wind energy is one of the important renewable energy resources available in nature. It is one of the major resources for production of energy because of its dependability due to the development of the technology and relatively low cost. Wind energy is converted into electrical energy using rotating blades. Due to environmental conditions and large structure, the blades are subjected to various vibration forces that may cause damage to the blades. This leads to a liability in energy production and turbine shutdown. The downtime can be reduced when the blades are diagnosed continuously using structural health condition monitoring. These are considered as a pattern recognition problem which consists of three phases namely, feature extraction, feature selection, and feature classification. In this study, statistical features were extracted from vibration signals, feature selection was carried out using a J48 decision tree algorithm and feature classification was performed using best-first tree algorithm and functional trees algorithm. The better algorithm is suggested for fault diagnosis of wind turbine blade. [ABSTRACT FROM AUTHOR]

• It is difficult to measure the dynamic status because of the wind turbine's far field working. A method for vibration analysis of wind turbine blades based on videogrammetry is proposed. • To obtain the space arc-like path coordinates of rotating blades, a videogrammetry experimental platform for rotating wind power blades was constructed. • The vibration information and modal frequency of wind turbine blades under operating conditions are calculated by extracting and analyzing the local periodic trajectory in a short time. • The vibration analysis of wind turbine blades based on videogrammetry method is compared with the calculation results of FEA and hammering experiment. The average error between the proposed method and the two methods is 4.355% and 4.63% respectively, within 5%. • This research can provide dynamic videogrammetry modal identification method and technical prototype for wind turbine blade condition monitoring and maintenance. It is difficult to measure the dynamic status because of the far fields working environment of the wind turbine. A method for vibration analysis of wind turbine blades based on videogrammetry is proposed. In order to obtain the space arc-like path coordinates of rotating blades, a videogrammetry experimental platform for rotating wind power blades was constructed. The space arc-like blade measuring points are collected and the error analysis is carried out by fitting the circular arc-like paths. The natural frequency of blade vibration is calculated based on Ensemble Empirical Mode Decomposition (EEMD) and fast Fourier transform (FFT). Evaluate the accuracy of the proposed method through finite element analysis (FEA) and hammering experiment. The results show that the modal & frequency from the presented method are basically consistent with the results of FEA and hammering experiment. It provides a theoretical method and technical means for measuring the dynamic vibration characteristics of blades. [ABSTRACT FROM AUTHOR]

Fatigue testing of a 48.3 m wind turbine blade needs to utilize the blade's oscillation range of 8.4 m along the flapwise direction for one million cycles. Control of such a remarkable oscillation range makes flapwise fatigue testing difficult and requires a large supply of energy. This study minimized the actuating force required for flapwise fatigue testing using an on-board-type resonance exciter with constant amplitude. Constraints related to the exciter's stroke and capacity and the maximum error between target loads and test loads were also considered. Based on a new algorithm suggested in this study, first, we found test setup candidates minimizing the maximum error under a given testing frequency and then found more candidates having slightly larger maximum errors as the exciter's location moved toward the blade's tip. Next, using damping ratio equations for the test blade, a required actuating force of the exciter at each test setup candidate was calculated. Considering the exciter's capacity, we found an optimum test setup that requires a minimum actuating force in the vicinity of the minimum of the maximum error between target loads and test loads. To conclude, the approach suggested in this study was able to conclusively achieve the required fatigue testing of the test blade, avoiding the adverse increase of fatigue testing time possible to happen due to a required actuating force larger than the exciter's capacity. Copyright © 2015 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Iran has a great potential for wind energy. This paper introduces optimization of 7 wind turbine blades for small and medium scales in a determined wind condition of Zabol site, Iran, where the average wind speed is considered 7 m /s. Considered wind turbines are 3 bladed and radius of 7 case study turbine blades are 4.5 m, 6.5 m, 8 m, 9 m, 10 m, 15.5 m and 20 m. As the first step, an initial design is performed using one airfoil (NACA 63-215) across the blade. In the next step, every blade is divided into three sections, while the 20 % of first part of the blade is considered as root, the 5% of last the part is considered as tip and the rest of the blade as mid part. Providing necessary input data, suitable airfoils for wind turbines including 43 airfoils are extracted and their experimental data are entered in optimization process. Three variables in this optimization problem would be airfoil type, attack angle and chord, where the objective function is maximum output torque. A MATLAB code was written for design and optimization of the blade, which was validated with a previous experimental work. In addition, a comparison was made to show the effect of optimization with two variables (airfoil type and attack angle) versus optimization with three variables (airfoil type, attack angle and chord) on output torque increase. Results of this research shows a dramatic increase in comparison to initial designed blade with one airfoil where two variable optimization causes 7.7% to 22.27 % enhancement and three variable optimization causes 17.91% up to 24.48% rise in output torque. [ABSTRACT FROM AUTHOR]

• A data-driven method is developed for health management of wind turbine blades. • The proposed method is based on self-supervised health representation learning. • Both vibration and SCADA data are applicable for the developed method. • Better performance can be achieved than using traditional methods. • The developed method has excellent generalization and anti-noise ability. To improve the efficiency and reliability of wind power generation, condition monitoring of wind turbines has drawn extensive attention worldwide. However, blade health monitoring is still challenging because of volatile operating conditions and the dependence on the assumption that healthy and unhealthy measurements can be naturally separated after the training stage. In this paper, a self-supervised health representation learning method is proposed to address these problems, and only healthy measurements are required in training. Specifically, data representations related to blade health conditions are learned by neural networks though data augmentation and an auxiliary task. In this case, the interference of operating circumstances and noise can be eliminated, and the volatility of measurements can be suppressed to establish accurate models of healthy operations. Moreover, the separability assumption is guaranteed by imposing constraints on the representation distributions of unhealthy samples, improving the reliability of decision making based on the learned knowledge. Blade health conditions are recognized using kernel density estimation. The satisfactory performance of the proposed method is demonstrated through laboratory and field measurements, achieving higher accuracy than existing approaches for online health monitoring. This work contributes to the economy of clean energy utilization. [ABSTRACT FROM AUTHOR]

Abstract: Alternative structural layouts for wind turbine blades are investigated with the aim of improving their design, minimizing weight and reducing the cost of wind energy. New concepts were identified using topology optimization techniques on a 45m wind turbine blade. Additionally, non-dimensional structural shape factors were developed for non-symmetric sections under biaxial bending to evaluate structural concepts in terms of ability to maximize stiffness and minimize stress. The topology optimization evolves a structure which transforms along the length of the blade, changing from a design with spar caps at the maximum thickness and a trailing edge mass, to a design with offset spar caps toward the tip. The shape factors indicate that the trailing edge reinforcement and the offset spar cap topology are both more efficient at maximizing stiffness and minimizing stress. In summary, an alternative structural layout for a wind turbine blade has been found and structural shape factors have been developed, which can quantitatively assess the structural efficiency under asymmetric bending. [Copyright &y& Elsevier]

The present paper investigates the performance of a special micro-wind turbine designed to capture wind energy in rural as well as urban environments. Different from traditional kilo- to megawatt size wind turbines which can be connected directly to the grid, the micro-wind turbine system is flexible in size and linked with small generators that generate electric power at the site of installation for easy applications. The main advantage of this micro-wind turbine, apart from its low cost, is that it can be propelled by a wind speed as low as 2 m/s. To extract more wind energy, several such micro-wind turbines can be connected together by their external gears into an array to increase their swept areas and hence power. In the study, the performance of a single micro-wind turbine was simulated using computational fluid dynamics (CFD) and validated through physical experiments. The experimental results on angular velocity and power developed showed a good agreement with those predicted by the CFD simulation. The validated computer model was then used for a parametric study of the wind turbine with varying blade subtend angles and number of blades, both of which affect the torque acting on the wind turbine and the power performance. The design of the wind turbine blade was optimized through the CFD simulation. This paper considers mainly the aerodynamic performance of a single turbine and issues relating to its practical deployment are not dealt with. [ABSTRACT FROM AUTHOR]

Recently wind energy has been alternatively used as a renewable energy resource instead of the mostly used fossil fuels due to their increasing scarcity and environmental issues. This work is to propose a structural design and analysis procedure for development of a 500 W class small wind turbine system which will be applicable to domestic use at a relatively low speed region like Korea. Structural analysis including load case study and stress, deformation, buckling, vibration and fatigue estimation was performed. In addition, the blade should be safe from the impact damage due to FOD (foreign object damage) including bird strikes. MSC Dytran was used to analyze the bird strike phenomenon on the blade, and the applied method, Arbitrary Lagrangian-Eulerian, was evaluated by comparison with the previous study results. Finally, the structural test was carried out and its test results were compared with the estimated results for evaluation of the designed structure. [ABSTRACT FROM AUTHOR]

Rapid growth in generating power from wind turbines led to application of long laminated composite blades. However, as the length of blades increases, the risk of failure due to excessive vibration increases. Therefore, a reliable wind power generator requires an efficient and accurate, yet economical structural health monitoring system to detect vibration and apply a reliable control to prevent from unpredicted failure. This paper presents an optimal, low cost and continuous vibration monitoring system for laminated composite blades using Fiber Bragg Grating (FBG). Utilizing a layerwise displacement theory, the Finite Element (FEM) model has been developed for the wind turbine blade. The optomechanical relations between strains and FBG wavelength shift have been presented to study the dynamic of a wind turbine blade. The reflected spectrum caused by modal displacement, interrogated by WDM method has been studied for vibration control. Numerical examples have been presented to compare the FEM and FBG results which show a very good agreement for the first 3 vibration modes. [ABSTRACT FROM AUTHOR]