Search Results (101)

Wind turbines operating under highly variable wind conditions require effective pitch-angle control to ensure maximum energy capture and structural protection. This study examines the performance of a 2.5 MW GEWE-B2.5-100 horizontal-axis wind turbine by quantifying how pitch-angle regulation affects power limitation, rotor-speed stability, and mechanical loading. Using an aerodynamic model, the maximum power point (MPP) was identified at an optimal mechanical angular speed of ω_OPTIM = 240.45 rad/s for V = 10 m/s, and the corresponding pitch-angle adjustments were determined for wind speeds up to 26 m/s, where β increases from 9.28° to 29.06° to maintain safe operation. Three dynamic case studies were conducted. Under sinusoidal wind variations between 10 and 14 m/s, PI-based pitch control limited rotor-speed oscillations to below 0.1%, ensuring stable operation. For exponential wind increases to 24 m/s and 34 m/s, the pitch angle rose to 28.48°, with rotor-speed overshoot remaining minimal at 0.004% and 0.006%, respectively. As stated in the manuscript, “dynamic pitch angle control significantly reduces rotor speed oscillations and mitigates excessive which indirectly contributes to alleviating potential structural stresses”. These results show that pitch-angle control is a key factor in turbine performance, enabling precise power capping at 2.178 MW and ensuring structural safety under extreme wind conditions. The proposed strategy supports reliable integration of large wind turbines into modern power systems. Full article

During the worldwide energy transition, wind power has become a leading development direction. Compared to large-scale horizontal-axis wind turbines (HAWTs), small-scale vertical-axis wind turbines (VAWTs) show potential, lack yaw mechanisms, adapt to wind direction changes, and are cost-effective. However, small-scale VAWTs operate in the near-surface atmospheric boundary layer and are sensitive to low-temperature and high-humidity climates, which cause blade icing. Ice buildup leads to fluctuations in aerodynamic loads, reduces power output, and diminishes stability. This study focuses on the NACA-0018 airfoil, using a low-temperature wind tunnel platform to simulate freezing durations to obtain ice characteristics on the blade surface. Based on ice profiles, numerical models were developed. Computational fluid dynamics (CFD) techniques were used to perform unsteady simulations of aerodynamic performance at various icing durations, investigating the influence on the power coefficient. The results indicate that the effect of icing duration on the average power coefficient depends on TSR. At the 5 min icing stage, the optimal tip-speed ratio decreases. Icing deteriorates aerodynamic performance at high tip-speed ratios, while producing positive optimization effects at low tip-speed ratios. This paper reveals the variation patterns of aerodynamic performance and differentiated mechanisms during the icing process of small vertical-axis wind turbine blades, providing a theoretical basis and data support for the development of surface anti-icing technologies and safe, efficient operation in low-temperature environments. Full article

This study focuses on the aerodynamic performance optimization of the SG6043 airfoil for application in small horizontal axis wind turbines (HAWTs) operating under low-Reynolds-number conditions. Recognizing the critical role of lift-to-drag ratio (Cl/Cd) in maximizing turbine power output, the research investigates the performance of SG6043 through design modifications and computational analysis. Initially, the baseline airfoil’s aerodynamic characteristics were verified using simulation tools like QBlade v0.96.3 software, confirming its previously reported performance. Subsequently, the airfoil was systematically modified by varying key parameters including thickness-to-camber ratio and angle of attack (AOA), operating at different Reynolds numbers. Among the modified versions, SG6043M5-7, SG6043M5-8, and SG6043M5-9 showed significant aerodynamic performance improvement, with SG6042M5-9 achieving the highest Cl/Cd ratio of 193.44 at Re = 6 × 10⁵ and AOA = 3.5°. The results demonstrated that a reduced thickness (5%) combined with moderate to high camber (7–9%) enhances the aerodynamic performance. Full article

A coupled non-destructive testing (NDT) workflow is proposed that integrates active infrared thermography (IRT) with laser-scanning-based reverse engineering (RE) to increase the reliability of detecting and interpreting damage in composite wind turbine blades across laboratory specimens and real components. IRT provides rapid, image-based qualitative localisation of potential anomalies, while 3D scan analysis supplies quantitative, geometry-aware verification and measurement of defect magnitude, reducing both false positives (design-related thermal signatures) and false negatives (weak thermal contrast). On polystyrene-filled profiles, IRT alone produced thermal anomalies unrelated to delamination; co-registered scan maps identified or ruled out local indentation, correctly attributing heat-flow patterns to internal design rather than damage. Outcome: the fused method disambiguates thermal indications and quantifies defect magnitude. On a vertical-axis wind turbine (VAWT) blade, the integration distinguished genuine geometric change from architectural effects under unknown internal structure and without CAD/reference scans, preventing false calls. For three horizontal-axis wind turbine (HAWT) blades, fleet-level scan comparison detected a significant tip deviation despite no clear local IRT anomalies, demonstrating complementary roles: scan = global quantitative homogeneity; and IRT = local qualitative verification. These findings operationalise thermal–geometric cross-validation and outline a path toward UAV-enabled inspections combining passive IRT and laser scanning for hard-to-access structures under real environmental conditions. Full article

Vertical-axis wind turbines (VAWTs) have emerged as a promising alternative for wind energy generation, particularly in offshore environments. However, their reliability continues to be limited by a critical component: the main bearing, which constitutes a major bottleneck in operation and maintenance (O&M). Analysis of its loading and operational conditions reveals complex scenarios, notably uneven radial load distributions on bearing elements, aerodynamic vibrations, and particular rotational dynamics, which render the VAWT main bearing highly susceptible to failure. To identify the damage mechanisms influencing its reliability, this review adopts a systematic comparative approach that leverages extensive failure data from various bearings used in horizontal-axis wind turbines (HAWTs). The findings indicate that these bearings are prone to failure during both operational and stationary periods, primarily due to contact fatigue and fretting damage, with stationary failures in offshore environments potentially progressing into tribocorrosion phenomena. By clarifying the domain of applicability of life prediction existing models and mitigation strategies, this review provides a structured framework for interpreting reported bearing failures in VAWTs and for guiding future experimental, modelling, and design efforts aimed at improving bearing reliability. Full article

Offshore wind-farm performance remains constrained by persistent wake deficits and turbulence that compound across intra-farm, intra-cluster, and inter-cluster scales, particularly under atmospheric neutral–stable stratification. A concept is advanced whereby offshore wind-farm yield may be augmented by pairing conventional horizontal-axis wind turbines (HAWTs) with lighter-than-air parafoil systems that entrain higher-momentum air and re-energise wakes, complementing yaw/induction-based wake control and enabling higher array energy density. A concise synthesis of wake physics and associated challenges motivates opportunities for active momentum re-injection, while a review of kite technologies frames design choices for lift generation and spatial keeping. Stability and control, spanning static and dynamic behaviours, tether dynamics, and response to extreme meteorological conditions, are identified as key challenges. System-integration pathways are outlined, including alignment and mounting options relative to turbine rows and prevailing shear. A staged validation programme is proposed, combining high-fidelity numerical simulation with wave-tank testing of coupled mooring–tether dynamics and wind-tunnel experiments on scaled arrays. Evaluation metrics emphasise net energy gain, fatigue loading, availability, and Levelized Cost of Energy (LCOE). The paper concludes with research directions and recommendations to guide standards and investment, and with a quantitative assessment of the techno-economic significance of kite–HAWT integration at scale. Full article

To address the scientific gap concerning optimal urban wind turbine morphology, this work presents an experimental performance comparison between two small-scale wind turbine designs: a conventional three-blade horizontal-axis wind turbine (HAWT) and a duct-equipped Ayanz-inspired screw-blade turbine. Both configurations were tested in a controlled wind tunnel under steady and transient wind conditions, including synthetic gusts designed to emulate urban wind patterns. The analysis focuses on power output, aerodynamic efficiency (via the power coefficient $C_P$), dynamic responsiveness, and integration suitability. A key novelty of this study lies in the full-scale experimental comparison between a non-conventional Ayanz screw-blade turbine and a standard three-blade turbine, since experimental data contrasting these two geometries under both steady and gusty urban wind conditions are extremely scarce in the literature. Results show that while the three-blade turbine achieves a higher $C_P$ peak and greater efficiency near its optimal operating point, the Ayanz turbine exhibits a broader performance plateau and better self-starting behavior under low and fluctuating wind conditions. The Ayanz model also demonstrated smoother power build-up and higher energy capture under specific gust scenarios, especially when wind speed offsets were low. Furthermore, a methodological contribution is made by comparing the $C_P$ vs. tip speed ratio λ curves at multiple wind speeds, providing a novel framework (plateau width analysis) for realistically assessing turbine adaptability and robustness to off-design conditions. These findings provide practical insights for selecting turbine types in variable or urban wind environments and contribute to the design of robust small wind energy systems for deployments in cities. Full article

Vertical-axis wind turbines (VAWTs) have received increasing research interest due to their structurally simple design and superior adaptability to gusty, multidirectional, and highly turbulent wind conditions. However, their relatively low efficiency of wind utilization remains a significant limitation, necessitating extensive research into design optimization and performance enhancement strategies. As we show, efficiency can be achieved by arranging the blades not evenly around the circumference, as in a traditional VAWT, but in groups called “blocks”, which extracts more energy from the air flow using aerodynamic and thermodynamic phenomena. The experimental results of a 20 kW VAWT in an independent certified laboratory strengthen the theoretical study and prove that the efficiency of the proposed system is 1.7 times higher than that of known VAWTs, as well as horizontal-axis wind turbines (HAWTs). Full article

This Vertical-axis wind turbines (VAWTs) are emerging as promising alternatives to conventional horizontal-axis wind turbines (HAWTs) for renewable energy generation, particularly in urban and offshore environments. Despite increasing interest, a comprehensive evaluation of their technical, economic, and environmental performance remains limited. This review, based on a targeted literature search, critically evaluates and compares the performance, economic viability, environmental impact, technological advancements, and adoption barriers of VAWTs and HAWTs. VAWTs demonstrate lower aerodynamic efficiency (20–35%) and capacity factors (20–35%) compared to HAWTs (efficiency 40–50%, capacity factors 30–45%), yet offer advantages such as omnidirectional wind capture, simpler ground-level maintenance, lower noise emissions, reduced avian impact, and greater feasibility for space-constrained urban settings. Economic analyses indicate that VAWTs typically have higher levelized costs of energy (60–80 EUR/MWh) than HAWTs (40–60 EUR/MWh), although these are partially offset by reduced operational costs. Environmental assessments favor VAWTs in terms of land use, biodiversity impact, and water consumption. Technological progress, including AI-based aerodynamic optimization, hybrid rotor designs, advanced composite materials, and Maglev bearings, has enhanced the competitiveness of VAWTs. The main adoption challenges are lower power output, scalability constraints, and lack of support from policymakers. While HAWTs remain dominant in large-scale wind energy production due to superior aerodynamic performance and economies of scale, VAWTs offer significant benefits for decentralized, urban, and offshore applications where installation flexibility, noise, and environmental considerations are critical. Continued innovation and more policy support could increase VAWT market penetration and contribute to more diversified, sustainable energy portfolios. Full article

The increasing complexity of tall buildings demands higher performance in serviceability and resilience, particularly regarding airflow control to reduce vibration-inducing forces. On the other hand, harnessing wind energy in suburban environments remains a challenge for sustainable city planning. This study examines airflow around a tall building designed for vertical wind farming, incorporating passive flow-control balconies and a roof-mounted horizontal-axis wind turbine (HAWT). Using 3D-resolved flow simulations, we analyse configurations with a 3-blade HAWT placed at varying heights and combined with different balcony types. The results show that turbine height has a stronger influence on rotational performance and near-wake dynamics than balcony geometry, while the mid-wake depends primarily on the building itself. We also find that shorter turbines reduce material and maintenance costs while maintaining similar power output at 30 rpm, whereas taller turbines offer only marginal safety improvements at roof level. Overall, the prototypes demonstrate the feasibility of combining facade roughness with on-site wind harvesting to maximise energy capture without duplicating infrastructure in suburban contexts. Full article

The rapid expansion of offshore wind energy requires exploring alternative turbine architectures capable of operating efficiently in deep waters. While horizontal-axis wind turbines (HAWTs) dominate the current market, vertical-axis wind turbines (VAWTs) offer potential advantages in wake recovery, structural integration, and scalability on floating platforms. This work proposes a methodological framework to enable a fair and reproducible comparison between the two concepts. The approach begins with site selection through spatial exclusion criteria, followed by acquisition and validation of wind data over at least one year, including long-term correction with reanalysis datasets. Technical specifications of both HAWTs and VAWTs (power curves, thrust coefficients, and rotor geometries) are compiled to build consistent turbine models. Wind resource characterization is carried out using sectoral Weibull distributions, energy roses, and vertical wind profiles. Annual energy production (AEP) for HAWTs is estimated with WAsP, while VAWT performance requires geometric normalization to a common top-tip height and subsequent correction factors for air density, turbulence sensitivity, and wake recovery. Case studies demonstrate that corrected AEP values for VAWTs may exceed baseline WAsP estimates by 6–20%, narrowing the performance gap with HAWTs. The framework highlights uncertainties in wake modeling and calls for dedicated computational fluid dynamics (CFD) validation and pilot projects to confirm large-scale VAWT viability. Full article

This study examines the effects of partial wakes caused by upstream turbine yaw control on the trailing-edge noise of a downstream turbine under stable and neutral atmospheric conditions. Using a combined model coupling the unsteady vortex lattice method (UVLM) with the Curl wake model, calibrated with large eddy simulation data, wake behavior and noise characteristics were analyzed for yaw angles from −30° to +30°. Results show that partial wakes slightly raise overall noise levels and lateral asymmetry of trailing-edge noise, while amplitude modulation (AM) strength is more strongly influenced by yaw control. AM varies linearly with wake deflection at moderate yaw angles but behaves nonlinearly beyond a threshold due to large wake deflection and deformation. Findings reveal that yaw control can significantly increase the lateral asymmetry in the AM strength directivity pattern of the downstream turbine, and that AM characteristics depend on the complex interplay between inflow distribution and convective amplification effects, highlighting the importance of accurate wake prediction, along with appropriate consideration of observer point location and blade rotation, for evaluating AM characteristics of a wind turbine influenced by a partial wake. Full article

This study presents a comparative analysis of horizontal-axis wind turbines (HAWTs) equipped with and without bio-inspired active oscillating vortex generators (VGs). The experimental investigation examines key aspects of mechanical integration and the resulting variations in aerodynamic behavior, demonstrating measurable improvements in electrical power output. The VGs were designed and implemented using servomechanisms and embedded control systems to enable oscillatory motion during operation. Experimental findings were validated against CFD simulations, indicating that the use of VGs increases annual energy production efficiency by 16.7%, primarily due to the stabilization of wake turbulence. While a reduction in output voltage was observed at wind speeds below 5 m/s, the VGs exhibited enhanced performance under variable wind conditions. These results highlight the potential of combining biomimetic design principles with electronically actuated flow-control devices to advance HAWT technology, improving energy efficiency and contributing to operational sustainability. Full article

The cost of energy generated by large-scale vertical-axis wind turbines faces great challenges for it to be competitive with conventional horizontal-axis wind turbines for offshore deployment. To become competitive, significant reductions in capital cost and operational costs would be competitive. A novel vertical-axis wind turbine that aims to meet these requirements is proposed: the X-rotor wind turbine. An early-stage feasibility study of exemplary two- and three-bladed 5 MW turbines is reported. The cost savings arising from two aspects of the concept that have the greatest impact, namely the power take-off system and O&M, are quantified. Two other aspects that could have a major impact on the cost of energy are the vertical axis rotor and the jacket. The masses for both are evaluated as proxies for their costs. The former costs are determined to be substantial relative to those of conventional HAWTs. Whereas the latter masses are determined not to be prohibitively greater relative to conventional HAWTs. Full article

One concern in the field of Horizontal Axis Wind Turbines (HAWTs) is what control strategies are needed to handle gust pulses in the wind to prevent extreme oscillations of the blades to reduce fatigue stress, prevent blade rupture, and extend the turbine’s operational life. In order to design innovative control strategies to modify the blade’s oscillatory response, it is crucial to establish the fundamental vibrational behavior of the blades when excited by gust pulses of different frequencies and amplitudes present in the fluctuating wind inflow. In a series of previous works, the authors presented a novel Reduced-Order Characterization (ROC) technique that provided an energy-based characterization of the fundamental modes of oscillation of wind turbine rotors when excited by combinations of wind gust pulses of different frequencies and amplitudes. The main focus of the present work is to extend these original notions of energy-based ROC to a universal technique expressed in terms of non-dimensional quantities that could be applied to turbines of any size, operating in any set of wind conditions, as long as they share geometrical and material similarity. The ROC technique provides a simple formula that is capable of predicting the dominant vibrational modes of a blade with sufficient precision to be useful in the determination of a control decision that can be computed in real time, an aspect of fundamental importance in dealing with rapid fluctuations in wind conditions. Full article