Design Of Wind Turbine Blades Research Articles

Novel method for determination the dynamic elastic modulus of composite wind turbine blades

A novel method, a non-destructive test, is developed to obtain the dynamic elasticity modulus of composite wind turbine blades. The proposed method is based on the free vibration theory of cantilever beams, the sectional analysis of laminated composites, the laminated composite theory, and the area contribution method. In response, the static elasticity modulus and the area properties of a hollow cross-section are obtained. On the other hand, by employing an equivalent beam that integrates all the cross-sections of a wind turbine blade. The method is tested with an equivalent blade, and all incidences of nonlinearity are avoided to obtain linear vibration modes; it is demonstrated that the free vibration test is applicable. Finally, it is observed that the first three natural frequencies were related to the dynamic elasticity modulus, where the third frequency shows an error of less than 1.2 %. This study revealed that the method for dynamics elasticity modulus has good potential to be used in the design of wind turbine blades as a quality control and non-destructive test.

A probabilistic fatigue life assessment method for wind turbine blade based on Bayesian GPR with the effects of pitch angle

AbstractThe fatigue behavior of large wind turbine blades is complex and stochastic due to their complex structure and operating environment. This paper focuses on developing a probabilistic fatigue life assessment method for wind turbine blades considering the uncertainties from wind velocity, material mechanical properties, pitch angle, and layer thickness. To improve the efficiency of stochastic fatigue behavior analysis of wind turbine blade, unidirectional fluid‐structure coupling (UFSC) and bidirectional fluid‐structure coupling (BFSC) analysis are employed to analyze the stochastic response. Then, Gaussian process regression (GPR) and Bayesian updating are combined to establish the stochastic fatigue behavior prediction model for wind turbine blade. On this basis, a modified S‐N curve formulation is proposed, and the fatigue life of wind turbine blade is analyzed by the modified S‐N curve and compared with the three‐parameter Weibull model. The results indicate that the proposed method for fatigue life assessment has better accuracy. The proposed probabilistic fatigue life assessment method with high accuracy and high efficiency, which is beneficial for the fatigue reliability design of wind turbine blades.

Design and optimisation of a 20 MW offshore wind turbine blade

In the global pursuit of Net Zero emissions by 2050, wind turbines have become a leading solution. These renewable energy generators offer a trifecta of benefits, significantly reducing CO2 emissions, minimizing environmental impact, and delivering cost-competitive clean power. However, the key to maximizing their potential lies in the aerodynamic design of the turbine blades. By improving the blade performance, researchers and engineers can significantly increase wind energy capture, propelling wind turbines to the forefront of the global transition to a sustainable future. Higher power generating wind turbines are needed to reach the Net Zero target. By upscaling the “DTU 10 MW Reference Wind Turbine”, this research has achieved an aerodynamically stable 20 MW offshore wind turbine blade design. Variable rotation speed and variable pitch angle configurations have been considered to achieve an ideal power curve. The aerodynamic performance has been evaluated and quantified for a length optimised blade design, wherein the power and thrust have been increased by 80.84% and 88.67%, respectively, at a rated wind velocity of 12 m/s.

Aeroacoustic investigation of a ducted wind turbine employing bio-inspired airfoil profiles

Ducted wind turbines for residential purposes are characterized by a lower diameter with respect to conventional wind turbines for on-shore applications. The noise generated by the rotor plays a significant role in the overall aerodynamic noise. By making modifications to the blade sections of the wind turbine, we can alter the contributions of aeroacoustic noise sources. This study introduces innovative wind turbine blade designs inspired by owl wing characteristics, achieving significant noise reduction without compromising aerodynamic performance. A three-dimensional scan of an owl wing was first employed to derive a family of airfoils. The airfoils were employed to modify the blade of a referenced wind turbine airfoil section at various positions on the blade span to determine a blade operating more efficiently at the tip-speed ratio of the original one. While maintaining the same aerodynamic performance, the bio-inspired profiles show a more uniform pressure coefficient distribution, considerably decreasing in the noise level. Furthermore, this study makes considerable progress in ducted wind turbine design by obtaining an 8 dB noise reduction and a 12% improvement in sound pressure level. An in-depth aerodynamic examination shows a 6.4% rise in thrust force coefficient and optimized power coefficients, reaching a peak at a tip speed ratio of 8, demonstrating improved energy conversion efficiency. The results highlight the dual advantage of the innovative design: significant noise reduction and enhanced aerodynamic efficiency, offering a promising alternative for urban wind generation.

Dufour and Soret diffusions phenomena for the chemically reactive MHD viscous fluid flow across a stretching sheet with variable properties

The flow of fluid on a slandering stretchable sheet with variable thickness can have several engineering applications like design and optimization of, aerodynamic structures such as wings and airfoils, wind turbine blade design, efficient cooling systems for electronic devices, power plants and industrial processes. Keeping in view these important applications, this work explores Darcy-Forchheimer flow of magnetohydrodynamics (MHD) fluid across a slandering stretchable sheet with variable thickness in the presence of chemically reactive effects, and heat source. The flow is impacted by the combined influences of diffusive-thermo and thermo-diffusive phenomena. The fluid is set into motion along x-axis due to the stretching behavior of the sheet with y-axis as normal to it. Similarity transformations are employed to convert the modeled equations into nonlinear ordinary differential equations. It has observed as outcomes of this study that velocity distribution has augmented with expansion in viscosity factor and has declined with growth in permeability factor, inertia factor, and magnetic factor for both scenarios h1=0.0 and h1=0.5 where the impacts are more significant for the scenario h1=0.0. Thermal distribution has declined with augmentation in Prandtl number, permeability factor and Dufour number while has upsurge with escalation in thermal source factor for both scenarios h2=0.0 and h2=0.5. Concentration distribution has diminished with escalation in Schmidt number, chemical reactivity factor and has augmented with growth in Soret factor for both the scenarios h3=0.0 and h3=0.5 with more significant impacts in the scenario h3=0.0. Stream lines and contour lines for fluid flow have also sketched for the scenarios h1=0.0 and h1=0.5 as well as for M=0.0 and M=2.0. Validation of the proposed model and the methodology has ensured through comparison with fine agreement amongst current results and previously published work.

Fluid–Structure Interaction Simulations of Wind Turbine Blades with Pointed Tips

The aerodynamic shapes of the blades are of great importance in wind turbine design to achieve better overall turbine performance. Fluid–structure interaction (FSI) analyses are normally carried out to take into consideration the effects due to the loads between the air flow and the turbine structures. A structural integrity check can then be performed, and the structural/material design can be optimized accordingly. In this study, three different tip shapes are investigated based on the original blade of the test wind turbine (Phase VI) from the National Renewable Energy Laboratory (NREL). A one-way coupled simulation of FSI is conducted, and results with a focus on stresses and deformations along the span of the blade are investigated. The results show that tip modifications of the blade have the potential to effectively increase the power generation of wind turbines while ensuring adequate structural strength. Furthermore, instead of using more complicated but computationally expensive techniques, this study demonstrates an effective approach to making quality observations of this highly nonlinear phenomenon for wind turbine blade design.

The Icing Characteristics of a 1.5 MW Wind Turbine Blade and Its Influence on the Blade Mechanical Properties

Ice accumulation significantly impacts the mechanical properties of wind turbine blades, affecting power output and reducing unit lifespan. This study explores the icing characteristics and their effects on a 1.5 megawatt (MW) wind turbine blade’s mechanical properties under various conditions, including wind speeds of 5 m per second (m/s) and 10 m per second, temperatures of −5 degrees centigrade (°C) and −10 degrees centigrade, and different liquid water contents, by using icing wind tunnel tests and structural statics analysis. The research reveals that ice predominantly forms in an irregular pattern on the leading edge of the blade. It is easy to produce corner ice and ice skating when the icing temperature and wind speed are higher, and the icing surface is rougher. When the other conditions remain unchanged, the decrease in temperature, an increase in wind speed, or a rise in liquid water content all lead to an increase in the average thickness of icing and the volume of icing at the leading edge, with the effect of the wind speed on the two being 147.8% and 147.9%, the effect of the liquid water content on the two being 39.9% and 53.5%, and the effect of the temperature on the two being 24.6% and 13.2%. The study finds that the blade tip experiences the maximum displacement in both iced and non-iced states, although the positions of peak equivalent stress and strain vary. The above study will also provide references for the design of new wind turbine blades and the anti-icing maintenance of wind turbine generator sets.

Multi-criteria optimal design of small wind turbine blades based on deep learning methods

The development of a Deep Learning (DL) model using multi-criteria optimal design of wind turbine blades is presented, focusing on the key variables TSR and Von Mises stress to predict: blade mass, power coefficient and natural frequency. The DL model was trained with data from three mathematical functions generated using distance-weighted inverse interpolation. The model allowed the generation of multiple feasible designs, which satisfy the design constraints. The BEM theory was used in the generation of the aerodynamic model of the 12.5 kW wind turbine using the NREL-S818 airfoil. Subsequently, the structural behavior of the blades was analyzed under three design load cases specified in IEC 61400-2. The results showed that in the training phase, the MAE, MSE and MSR error metrics were an essential guide in the development of the DL model. Interesting behaviors were observed due to the diverse results obtained, which are probably due to the multidimensional fits that are difficult to observe in the fit functions generated. However, training between 200 and 250 epochs performed better, with errors ranging from 0.05 to 0.120 for the MAE. The DL model exhibited the remarkable ability to predict the optimal output variables, with accuracy ranging from 90% to 98%.

Optimal airfoil selection for small horizontal axis wind turbine blades: A multi-criteria approach

Over the last century, the growing demand for clean energy has emphasized wind energy as a promising solu-tion to address contemporary energy challenges. Within the realm of wind energy, the wind turbine plays a pivotal role in harnessing the kinetic energy of the wind and converting it into electrical power. Among the various components of the wind turbine system, turbine blades assume a critical role in capturing the wind's kinetic energy and converting it into rotational motion. Consequently, the design of wind turbine blades holds the utmost importance in determining the overall performance and efficiency of the entire wind turbine system. One essential aspect of blade design involves selecting an appropriate airfoil. Throughout history, numerous airfoil profiles have been developed for various applications. Notably, National Advisory Committee for Aeronautics (NACA) and National Renewable Energy Laboratory (NREL) airfoils have been tailored for aircraft and large-scale wind turbine blades, respectively. However, the quest for suitable airfoil types for small-scale wind turbine blades has been ongoing. This study delves into an examination of over 62 distinct NACA and NREL aerofoil types tailored for small horizontal-axis wind turbine blades. Employing specialized software, namely QBlade, specifically designed for modeling and simulating wind turbine blades, the study calculates key parameters such as power output, stress, deformation, and weight for each airfoil. Subsequently, based on the simulated data, the optimal airfoil is identified using the Technique for Order Preference by Similarity to Ideal Solution (TOPSIS) multi-criteria selection approach. This selection process takes into account simulation results pertaining to power output, stress, deformation, and weight. The decision-making process involving multiple criteria is facilitated using Excel and Python. The findings of this study reveal that among the 62 airfoil types under consideration, the NACA 0024, NACA 2424, and NACA 4424 airfoils emerge as the most suitable choices for small horizontal-axis wind turbine blades.

Optimized Design of Bio-Inspired Wind Turbine Blades

Optimized Design of Bio-Inspired Wind Turbine Blades

Vertical Axis Wind Turbine for Low Wind Speed Environment: Effect of Scoop Harmony Blade

The wind condition in Malaysia is in the low-speed category with an average speed of 1 ms-1 to 4 ms-1. Effect of ground level relies significantly on the wind speed distribution. Despite these conditions, it is less suitable for the development of horizontal wind turbine as an energy source. The obvious weakness is the lack ability to self-start and predict the wind direction thus affects the energy efficiency output. To overcome this problem, improvement of the vertical axis wind turbine design is observed to be the solution in replacing horizontal axis wind turbine. Hence, this study is to investigate a suitable type of vertical axis wind turbine blade design for the best performance RPM output in a low-speed wind environment. The investigation was conducted in a Longwin LW-9300R subsonic wind tunnel at 0 ms-1 to 10 ms-1 wind speed condition from three wind turbine blades specified as Solid Harmony, Scoop Harmony and Conventional Savonius blade with angle of 90º, 135º and 180º to determine the highest RPM productivity. Result shows that Scoop Harmony blade delivers the highest RPM blade output while Savonius 180º is seen to have the highest self-start blade achieved at 64 rpm at 1 ms-1 wind speed. However, Solid Harmony shows an acceptable range TSR of 0.5 with difference of 23% lower than Scoop Harmony. This shows that both Scoop Harmony has a higher performance RPM but Solid Harmony still has the potential design to be applied at low-speed condition due to its low TSR output.

Design of a low velocity wind turbine blades for power generation: part I‐aerodynamic performance

Design of a low velocity wind turbine blades for power generation: part I‐aerodynamic performance

An ML-based wind turbine blade design method considering multi-objective aerodynamic similarity and its experimental validation

Model test is an essential technique to study the aerodynamic performance of wind turbines. To overcome the poor aerodynamic performance of scaled models caused by the scaling effect, this study proposes an innovative blade design method for scaled model testing based on machine learning (ML). The method achieves satisfactory similarity between the thrust and power coefficients under multiple operating conditions of the model and prototype. Furthermore, a case study of the NREL 5-MW wind turbine is carried out with wind tunnel tests to validate the effectiveness of the proposed method. Obtained results suggest that the aerodynamic performance of redesigned blade closely mirrors that of the prototype under multiple operating conditions, reaching 97.59 % (thrust) and 97.87 % (power) coefficients of the prototype at the rated operating condition, respectively. With this technique, aerodynamic performance similarities between the redesigned blade and the prototype can be enhanced, contributing to more accurate scale model testing.

Investigating aerodynamics of a 3D blade in rainy conditions: Application of hybrid superhydrophobic-hydrophilic surfaces

In the realm of wind turbine blade design, it is essential to consider the impacts of real-world environmental conditions. Among these, rain stands out as an unpredictable natural phenomenon, with its intensity varying based on environmental factors. This study delves into the aerodynamic effects of different rain intensities on a three-dimensional wind turbine blade—a crucial investigation since rain can influence both the efficiency of energy capture and operational safety. A custom OpenFoam solver was employed for numerical analysis, and its accuracy was first verified by contrasting simulation outcomes with experimental results. Our findings reveal that while the critical angle of attack is 14° in dry conditions, it increases to 17° under the influence of rain. When maintaining a constant angle of attack, rainy conditions result in a lowered lift coefficient and a heightened drag coefficient. Significantly, the thickness of the boundary layer and the presence of a separation bubble are deeply affected by rain intensity. During heavy rainfall, the boundary layer's thickness can diminish by up to six times compared to dry scenarios. Towards the study's conclusion, blades were integrated with hybrid superhydrophobic-hydrophilic surfaces to enhance aerodynamics during rainfall. Data suggests that these surface alterations effectively regulate the boundary layer's thickness and manage the flow separation zone, ultimately boosting the blade's aerodynamic efficiency in wet conditions. These findings set the stage for subsequent research focused on developing blade designs responsive to the ever-fluctuating environmental dynamics.

Aerodynamic characteristic analysis of wind turbine blades based on CSA-KJ airfoil optimization design

In order to enable the offshore wind farm to produce electric energy efficiently, stably and economically, the optimization method of CSA-KJ airfoil is proposed, and the optimized CSA-KJ4412 airfoil is obtained, and the aerodynamic characteristics of the airfoil are compared and analyzed. Combined with Wilson method, the high-power CSAKJ4412-08 wind turbine blade is designed, the flow field characteristics of the blade under different working conditions are simulated and analyzed, and its power is verified. The results show that compared with the NACA4412 airfoil, the average lift-drag ratio coefficient and the maximum value of the CSA-KJ4412 airfoil increase. Meanwhile, the pressure distribution rises, and the aerodynamic characteristic is better. The fluid around CSAKJ4412-08 blade at different attack angles is attached to the blade surface tightly for adhesive flow, and no stall phenomenon is identified. The pressure on the suction and pressure surfaces for the optimized CSAKJ4412-08 blade shows an opposite trend as the wingspan in-creases, leading to an increase in the pressure difference between the upper and lower surfaces, thereby improving the lift of the blade. In the range of –30° to 30° attack angle, the power of CSAKJ4412-08 blade increases first and then decreases as the attack angle rises, and the ratio of the maximum power to the rated value reaches 71.38 %, indicating that the optimized CSAKJ4412-08 blade exhibits better aerodynamic characteristics. The relevant results can provide technical reference for the optimal design of wind turbine blades.

Design and Optimisation of Horizontal Axis Wind Turbine Blades Using Biomimicry of Whale Tubercles

Wind speed is the major factor in generating power in a wind turbine. However, due to the non-optimum and redundant design of wind turbine blades, not nearly enough wind is captured for utilization. In the present study, modifications were done on the leading edge of the HAWT blade using tubercles showing their effects on aerodynamic performances. From this research, the following results found concerning the performances of HAWT with leading-edge tubercles were that; blades with tubercles on the leading edge will have superior performance in the post-stall regime by 27%, tubercles with a smaller amplitude and lower wavelength will produce higher lift and lower drag in the low wind speed condition, and tubercle blade will have a stable and smooth performance in varying wind speed conditions, producing higher torque and power at low wind speed. Using a small wind turbine model, SolidWorks Motion Analysis Simulation was used for dynamic modeling to evaluate and determine the force and torque of the mechanical structure. These results were compared and examined using standard wind turbine blades which showed an improvement of 30% in efficiency.

Material Selection of Face Sheet of Sandwich Plate Used in Blade of Wind Turbine Using MCDM Method

Abstract: The design and materials of wind turbine blades are crucial in terms of performance and durability. They are an essential part of the energy sector. In this article, we use the Multi-Criteria Decision Making (MCDM) method to suggest a material selection method for the face sheet for a sandwich shell/web for wind turbine blades. To determine the best material out of all the options, the MCDM method allows the evaluation of multiple criteria. The suggested method takes into account a number of things, including weight, price, mechanical qualities, and environmental impact. Aluminium, Carbon Fibre Reinforced Polymer, and Glass Fibre Reinforced Polymer were the materials assessed in this study. According to the MCDM results, CFRP is the best material for a wind turbine sandwich shell or web's face sheet when taking the chosen criteria into account. The suggested strategy offers a method for selecting materials that is systematic and all-inclusive and can be used in other fields and applications

Enhancing Savonius Vertical Axis Wind Turbine Performance: A Comprehensive Approach with Numerical Analysis and Experimental Investigations

Small-scale vertical-axis wind power generation technologies such as Savonius wind turbines are gaining popularity in suburban and urban settings. Although vertical-axis wind turbines (VAWTs) may not be as efficient as their horizontal-axis counterparts, they often present better opportunities for integration within building structures. The main issue stems from the suboptimal aerodynamic design of Savonius turbine blades, resulting in lower efficiency and power output. To address this, modern turbine designs focus on optimizing various geometric aspects of the turbine to improve aerodynamic performance, efficiency, and overall effectiveness. This study developed a unique optimization method, incorporating a new blade geometry with guide gap flow for Savonius wind turbine blade design. The aerodynamic characteristics of the Savonius wind turbine blade were extensively analyzed using 3D ANSYS CFX software. The optimization process emphasized the power coefficient as the objective function while considering blade profiles, overlap ratio, and blade number as crucial design parameters. This objective was accomplished using the design of experiments (DOE) method with the Minitab statistical software. The research findings revealed that the novel turbine design “OR0.109BS2BN2” outperformed the reference turbine with a 22.8% higher power coefficient. Furthermore, the results indicated a trade-off between the flow (swirling flow) through the gap guide flow and the impact blockage ratio, which resulted from the reduced channel width caused by the extended blade tip length.

A study of Stall-Induced Vibrations using Surrogate-Based Optimization

Stall-Induced Vibrations (SIV) are an important design consideration for wind turbine blade design, especially for large, modern, wind turbines with highly flexible blades. Their severity depends on both the inflow and the structural characteristics of the blades. Studying SIV has a high computational cost, because it requires high-fidelity aeroelastic simulations, and potentially a large number of input variables. In an effort to reduce the computational cost of the domain exploration, in this work we have adopted a Surrogate-Based Optimization (SBO) framework. This way, the combination of input variables that lead to SIV can be explored with the minimum number of aeroelastic simulations. The proposed SBO framework can use any type of surrogate model, and leverages Delaunay triangulation to iteratively select samples to refine the surrogate model. The occurrence and severity of SIV on the IEA 10MW turbine is studied in a five variables space consisting of: wind speed, yaw angle, vertical wind shear, wind veer, and atmospheric temperature. A well-trained surrogate model is developed and used to predict the damping ratio of the first blade edgewise mode in the entire inflow space at a reduced computational cost. Sensitivity analysis of the predicted damping ratio shows that yaw angle is the most influential variable, while temperature is the least influential variable in terms of inflow conditions that can lead to the occurrence of SIV. Inflow conditions with a moderate yaw angle (around 10–25 deg), high wind speeds, and moderate to high negative veer are found to lead to severe SIV. This study should serve as a guiding tool to decide the scope of the more computationally expensive simulations such as high-fidelity CFD-based aeroelastic simulations which can provide a more accurate description of SIV.

Drag reducer design of wind turbine blade under flap-wise fatigue testing

Wind turbine blade fatigue testing is necessary to verify the reliability of the structure design. A large aerodynamic drag is experienced under flap-wise fatigue testing since the prototype blade under testing moves through the air as a bluff body. An ellipse-sectional drag reducer made of a thin-wall shell is usually installed near the blade tip to alleviate the aerodynamic drag resistance. However, the correlation between drag reducer profile shape and aerodynamic characteristics has not been studied. In addition, the mass and stiffness of the drag reducer also have an adverse influence on the fatigue testing quality. In this study, a shuttle-shaped airfoil is proposed and an optimization design framework is built by a high-efficient aero-structure integrated numerical method. Results indicate that, as compared to the elliptical airfoils, an optimized shuttle-shaped airfoil can more effectively reduce the aerodynamic drag and at the same time improve the prototype blade test reliability.