Search Results (102)

Real-time monitoring of wind turbine aeroelastic damping is crucial for dynamically adjusting operational strategies and enhancing turbine stability and economic efficiency. However, since aeroelastic damping cannot be directly measured and effective industrial methodologies remain limited, this study proposes an innovative hybrid prediction framework for aeroelastic damping of wind turbine blades based on field-measured turbine data. First, a general model for calculating blade root reaction forces was developed using blade element momentum theory, considering multiple influencing factors such as motor torque, gravitational force, and centrifugal force. Linear regression and decision tree algorithms were employed to identify key coefficients in the theoretical model, thereby providing accurate hub load inputs for finite element (FE) calculations of tower aeroelastic damping through blade physical modeling. Second, a full-scale FE model of the wind turbine was constructed in Abaqus, where dynamic responses were computed using hub axial forces as inputs and compared with field data to obtain aeroelastic damping values, yielding high-quality labeled data for training machine learning models. Finally, an aeroelastic damping dataset was generated through data analysis and downsampling, and a long short-term memory recurrent neural network was trained as the prediction model. Simulation results demonstrated high accuracy, with mean prediction errors below 2.2% and maximum errors below 2.5% on real turbine datasets. In addition, experimental validation further confirmed the effectiveness of the proposed method. The model features a computationally efficient architecture, strong real-time applicability for high-dimensional inputs, and considerable potential for practical implementation. Full article

Accurate modeling of wind turbine power curves is essential for performance assessment, energy forecasting, condition monitoring, and operational optimization in wind energy systems. This study presents a SCADA-based comparative assessment of established power curve modeling approaches through a single-site case study conducted on a low-power Vertical Axis Wind Turbine (VAWT) operating under real environmental conditions at the University of the Isthmus, located in the Isthmus of Tehuantepec, Oaxaca, Mexico. The evaluated methods included the maximum power curve, an aerodynamic model based on Blade Element Momentum Theory (BEMT), parametric approaches using polynomial and logistic regressions, and non-parametric data-driven methods based on Random Forest (RF), Gaussian Process Regression (GPR), and Kernel Density Estimation (KDE). One year of SCADA data, including wind speed and generated power measurements, was analyzed, while model performance was assessed using RMSE, MAE, and R² metrics. The results showed that the machine learning approaches achieved the lowest prediction errors among the evaluated models, with RF providing the best overall performance (RMSE = 7.4%, MAE = 4.8%, R² = 0.9814), followed by GPR and KDE under the investigated operating conditions. Additionally, Weibull analysis yielded parameters of k = 1.887 and c = 7.875 m/s, while the largest prediction errors were observed within the partial-load operating region (approximately 4–10 m/s) and as the turbine approached the rated operating condition (approximately 10–12 m/s). These findings indicate that, for the investigated low-power VAWT operating at the experimental site, non-parametric approaches provided the most accurate representation of the power curve among the evaluated models, highlighting the potential of SCADA-based data-driven techniques for comparative model assessment under similar operating conditions. Full article

Continuous population growth will lead to further expansion and densification of urban environments. In this context, Urban Air Mobility (UAM) has emerged as a new transportation solution through the use of Vertical Take-Off and Landing (VTOL) aircraft, more precisely, configurations such as lift-plus-cruise tilt-rotors. During the conceptual design phase, propeller design methodologies commonly reported in the literature rely on vortex-based approaches or actuator disk theory. However, the accuracy of these methods strongly depends on the inflow angle and operating conditions. This paper introduces an analytical model to predict propeller thrust at a 90° inflow angle (edgewise flight), based on a correction of the thrust under axial flight conditions and the propeller geometry evaluated at 75% span. The approach relies on local velocity and angle of attack estimations derived from classical Blade Element Momentum Theory (BEMT) with an additional correction to account for stall effects at high angles of attack. This capability is particularly relevant for modeling lift-plus-cruise tilt-rotor configurations cruise phase during early design stages while maintaining minimal computational cost. The proposed model is validated against wind tunnel measurements for several propellers tested at different global pitch angles, varying from 0 m/s to 9.1 m/s of windspeed and 1300 to 6200 rpms, demonstrating the applicability of the developed formulation for blades with twist angles up to 16°. Full article

This paper presents AeroelasticQ, a modular, high-performance aeroelastic simulation code for wind turbines, with particular emphasis on future applicability to multi-rotor configurations. The framework is organized into three core components: a flexible-blade structural solver, an airfoil-based aerodynamic solver, and a two-mesh aero-structural mapping module for transferring loads and kinematics between the aerodynamic and structural discretization. The implementation is written in C++17 using the Eigen linear algebra library (v5.0.0), and OpenMP (v5.1) is employed to enable rotor-level parallel execution for multi-rotor applications. The structural dynamics are formulated using Kane’s dynamic method combined with modal superposition, while the aerodynamic loads are computed using three-dimensional blade element momentum theory. The coupled and uncoupled modules are validated in the time domain against OpenFAST (v4.1.2) AeroDyn, ElastoDyn, and the coupled AeroDyn–ElastoDyn configuration using the NREL 5 MW reference wind turbine. The rotor-level aerodynamic validation gives mean absolute errors of 8.94 × 10⁻⁴, 2.82 × 10⁻⁴, and 2.71 × 10⁻⁵ for C_t, C_p, and C_q, respectively, while the coupled aeroelastic cases show close agreement in blade tip deflections, blade root loads, and aerodynamic power. A rigid three-rotor verification confirms the multi-rotor load-aggregation framework, with tower base thrust and overturning moment errors below 1.5% and 2% NRMSE, respectively, in both all rotors operating and one operating/two-parked configurations. In single-thread benchmarks, AeroelasticQ achieves speedups of 5.23×, 19.69×, and 3.65× in the aerodynamic-only, structural-only, and fully coupled modes, respectively. In the multi-rotor benchmark, the five-rotor case achieves a parallel speedup of 2.55× with a parallel efficiency of 51%. Full article

Accurate power estimation is fundamental to effective tidal turbine design. While turbines are typically designed for specific Tip Speed Ratio (TSR) ranges, the Reynolds number ($Re$) can vary significantly even at a constant TSR depending on flow velocity and turbine scale. Such variations in $Re$ can fundamentally alter the flow characteristics around the blades, directly impacting performance. Conventionally, $Re$-dependent lift and drag coefficients are incorporated into Blade Element Momentum Theory (BEMT) to address these variations, often supplemented by hub and tip loss corrections. However, since BEMT relies on two-dimensional airfoil characteristics, it may not fully capture the complex three-dimensional viscous effects that occur during actual operation. Therefore, this study employs three-dimensional CFD simulations to quantitatively evaluate $Re$ effects on turbine performance. By quantifying power generation deviations across a broad $Re$ spectrum, the results show that discrepancies at identical TSRs range from 0.312% to 7.32%. Notably, these differences stabilise near 1% when $Re$ exceeds $1.0\times {10}^7$. Furthermore, the underlying causes of these scale effects were identified by decomposing the torque into shear and pressure components. These quantified indicators provide a practical basis for incorporating Reynolds number effects into the turbine design process, thereby contributing to more accurate full-scale performance prediction. Full article

In the analysis and design of wind turbines, aeroelastic analysis is required that considers elastic structure and control in addition to aerodynamic characteristics. In recent years, with the increase in size and reduction in the cost of wind turbines, problems have emerged that cannot be addressed with the standard analysis methods. The accuracy of the Blade Element and Momentum (BEM) theory, which is the most common aerodynamic analysis and design theory, is reduced in conditions where three-dimensional effects such as radial flow are not negligible. Furthermore, full-model Computational Fluid Dynamics (CFD), which is commonly used for complex aerodynamic problems, is not applicable for the design calculation of wind turbines considering itscomputational demands. To address these challenges, the Actuator Line Model (ALM) can be utilized as practical load analysis methods that account for structural elasticity, control, and fluctuating winds—offering a level of fidelity between both approaches. However, the conventional ALM does not account for the stall delay (SD) observed in the inboard section of rotor. In this study, an ALM based on CFD is developed by incorporating Snel’s stall delay model, which was developed for BEM. Additionally, the use of the NREL 5 MW reference wind turbine rotor results in the load distribution of the inboard section of this developed model to be comparable to that of the full-model CFD; however, a similar observation is not made for the conventional BEM. Full article

The horizontal-axis tidal turbine is a representative device for harnessing ocean tidal energy, and the structural optimization of its blades is crucial for enhancing the power capture efficiency. In this work, the twist and chord distributions of the blade are determined using an improved Blade Element Momentum (BEM) approach, in which tip and hub loss factors are employed to enhance the modeling accuracy, and these results are employed to construct a parametric model of the original rotor. Due to its simplified assumptions and inability to capture three-dimensional flow effects, computational fluid dynamics (CFD) simulations were carried out to evaluate the hydrodynamic performance and flow analysis of the designed rotor. Further, the orthogonal test method was used to optimize the hydraulic performance of the rotor. Three optimization parameters, namely hub diameter, airfoil type, and maximum airfoil thickness, were set with three levels. Based on the orthogonal design scheme, nine rotor configurations were generated, and their energy capture characteristics and flow fields were subsequently evaluated through numerical simulations. The analysis indicates that the choice of airfoil exerts the strongest impact on the rotor’s energy capture efficiency, while the influences of maximum airfoil thickness and hub diameter follow in descending order. Consequently, the optimized rotor adopts a NACA63-415 airfoil with a reduced maximum thickness of 0.9 T₀ and an intermediate hub diameter of 15%R, achieving a power coefficient of 0.445 at the design tip-speed ratio of 4, corresponding to a 3.08% improvement compared with the original design. Flow field analysis demonstrates that the optimized geometry promotes a more uniform spanwise pressure distribution and effectively suppresses flow separation, thereby enhancing the overall hydrodynamic efficiency. Full article

Due to the complexity of aerodynamic coupling between the duct and propeller, the overall design and optimization of ducted fans often require extensive experience and time. Meanwhile, traditional design methods based on Blade Element Momentum Theory, Lifting Surface Theory, Vortex Lattice Methods, and Panel Method usually exhibit certain deviations between their design results and actual outcomes. This is because these approaches struggle to accurately calculate the aerodynamic coupling effects between the duct and propeller, coupled with numerous simplifications inherent in the methods themselves. Considering the strong nonlinear coupling relationship between the duct and propeller, the Response Surface Method (RSM), which enables efficient and accurate analysis of multi-variable coupling effects, was selected for the parameter design and optimization of ducted fans. Computational Fluid Dynamics (CFD) was applied to evaluate the impact of design parameters on overall aerodynamic performance. This approach addresses the limitations of traditional methods, including low design accuracy, high computational cost, and insufficient multi–objective optimization capability. It explicitly models multi-parameter coupling and nonlinear effects using a small number of experimental points, combined with the Multi-Objective Genetic Algorithm (MOGA) to find the global optimum. Compared to the baseline duct fan, the optimized duct fan achieved a 9.6% increase in overall lift and a 9.5% improvement in lift efficiency. Full article

Although the hub blockage effect is generally disregarded for large-sized horizontal axis wind machines, it can significantly affect the performance of small-sized turbines whose ratio between the hub and rotor radii can attain values up to 25–30%. This article proposes a generalisation of the Blade-Element/Momentum Theory (BE/M-T), accounting for the effects of the hub presence on the rotor performance. The new procedure relies on the quantitative evaluation of the radial distribution of the axial velocity induced by the hub all along the blade span. It is assumed that this velocity is scarcely influenced by the magnitude and type of the rotor load, and it is evaluated using a classical CFD approach applied to the bare hub. The validity and accuracy of the modified BE/M-T model are tested by comparing its results with those of a more advanced CFD-actuator-disk (CFD-AD) approach, which naturally and duly takes into account the hub blockage, the rotor presence, an and the wake divergence and rotation, and the results are validated against experimental data. The comparison shows that the correction for the hub blockage effects in the BE/M-T model significantly reduces the differences with the results of the reference method (CFD-AD) both in terms of global (power coefficient) and local (thrust and torque per unit length) quantities. Full article

This work investigates the influence of ground effect on the performance of a UAV propeller through a combined experimental, analytical, and numerical approach. A dedicated test bench was designed and constructed to enable controlled measurements of thrust and power under static conditions. During experimental campaigns, it was observed that the measured thrust significantly exceeded theoretical free-air predictions, suggesting the presence of a ground-like amplification effect. To quantify and validate this phenomenon, complementary methods were employed: blade element momentum-based analytical modeling corrected for ground proximity and high-fidelity CFD simulations performed using ANSYS CFX. Three configurations were analyzed numerically—an isolated propeller, a propeller with a motor, and a propeller–motor–mounting plate configuration—highlighting the progressive impact of structural elements on the flow field. The results showed close agreement between corrected analytical predictions, CFD solutions, and experimental data, with deviations below 8%. The presence of the mounting plate induced pressure redistribution and jet reflection, analogous to the helicopter ground effect, leading to thrust amplification of up to 30% relative to free-air conditions. This study confirms the critical role of the experimental setup and mounting configuration in propeller characterization and establishes a validated methodology for capturing ground effect phenomena relevant to UAV propulsion systems. Full article

The wake characteristics of tidal turbines are significantly influenced by turbulence intensity (TI) and flow velocity in the marine environment. This study employs the Blade Element Momentum (BEM)–CFD method to model two-bladed horizontal tidal turbine wakes, simplifying the turbine geometry while ensuring computational efficiency. The numerical model, validated against experimental data, demonstrates reliable accuracy. Simulations were conducted for background TI levels of 2%, 6%, 10%, 14%, and 18%. Results indicate that wake regions initially expand and then contract, with the contraction point moving closer to the turbine as TI increases. At 2% TI, the wake influence region extends to an axial distance/diameter (X/D) ratio of 20, while at 18% TI, contraction begins at X/D = 4. Low TI results in more extensive low-speed regions, whereas high TI accelerates wake recovery. As TI increases, the wake’s turbulence rapidly blends with the background, leading to a reduction in turbulence increments within the wake. Additionally, an analytical wake model for tidal turbines was developed, incorporating turbulence intensity into the formula. The predicted curve exhibited good agreement with the CFD data. This model enables a quick and efficient prediction of wake velocity changes under varying turbulence intensities. Full article

A new approach for optimizing the blade profile of a horizontal axis wind turbine is proposed in this paper, based on the combination of the Blade Element Momentum (BEM) method and Proper Generalized Decomposition (PGD). The resulting algorithm was implemented in MATLAB (R2010A). To investigate the applicability of the proposed BEM-PGD method, simulations were conducted using the NREL phase VI turbine. By focusing on the tangential force coefficient as a parametrized solution, the study demonstrated a 21.7% improvement in the power coefficient relative to the baseline blade corresponding to a 20 kW turbine, while the tip speed ratio (TSR) ranged from 1 to 12, as assessed through a quantitative metric comparing the optimized and reference curves. These advancements are attributed to the algorithm’s capability to parameterize the solution and to select the appropriate airfoil type, thickness, chord, and twist, allowing for an optimized and realistic blade design. Full article

This article presents a methodology for the synthesis of horizontal-axis wind turbines operating on the principle of lift. The profile geometry is synthesized using the Vortex–source distribution method following Glauert’s approach. The blade shape is developed using the Blade Element Momentum Theory. Efficiency is determined with Computational Fluid Dynamics. The methodology uses a multifactor numerical experiment, with the objective function defined as maximizing lift-to-drag ratio of the blade profile. Validation of the obtained power curves is performed with QBlade and XFoil and confirmed experimentally on a laboratory test bench. The proposed methodology demonstrates improved accuracy in predicting the power coefficient and the optimal operation regime of horizontal-axis wind turbines at low Reynolds numbers. Full article

Small-scale wind turbines (SWTs) represent a promising solution for the energy transition and the decentralization of electricity generation in non-interconnected areas. Conventional strategies to improve SWT performance often rely on active pitch control, which, while effective at rated conditions, is too costly and complex for small systems. An alternative is passive pitch control through bend–twist coupling in the blade structure, which enables self-regulation and improved power generation. This work proposes a novel blade design methodology for a 5 kW SWT that integrates passive bend–twist coupling with conventional pitch adjustment, thereby creating a hybrid passive–active control strategy. The methodology encompasses the definition of aerodynamic blade geometry, laminate optimization via genetic algorithms combined with finite element analysis, and experimental characterization of composite materials. Aerodynamic–structural interactions are studied using one-way fluid–structure simulations, with responses analyzed through the blade element momentum method to assess turbine performance. The results indicate that the proposed design enhances power generation by about 4%. The study’s originality lies in integrating optimization, structural tailoring, and material testing, offering one of the first demonstrations of combined passive–active pitch control in SWTs, and providing a cost-effective route to improve efficiency and reliability in decentralized renewable energy systems. Full article

This paper proposes a solution for the design of high-performance propellers optimized for various flight conditions. Considering both propulsion and electric motor efficiencies, a new design optimization methodology is proposed. The optimization of the electric propulsive system is directly achieved by simultaneously analyzing the aerodynamic performance of the propeller and the motor. This study is focused on small, low-speed Remotely Piloted Aircraft Systems, addressing the design of fixed pitch propellers that operate efficiently over the entire speed range. The aerodynamic methodology uses combined blade element and momentum theory, which is adequate for a preliminary design phase with low computational time. For the aerodynamic coefficients of the airfoils used in these applications, at low Reynolds numbers, a new database was developed that incorporates airfoil experimental data and analytical methods to cover a wide range of angles of attack, beyond stall. For the modelling of the motor behavior, an idealization of the circuit was carried out, which considers its basic electric parameters. The results show significant improvements with respect to the information available for a current commercial propeller. Full article