Optimization Of Wind Turbine Blades Research Articles

Experimental Investigation and CFD Analysis of Wind Turbine Blades with Different Attack Angles

The escalating global demand for energy coupled with escalating environmental concerns has underscored the imperative of efficacious energy conversion from renewable reservoirs. Among these, wind energy has ascended as a pragmatic and ecologically conscientious solution. Its ascent, outpacing conventional fuels such as coal, underscores the necessity to comprehend its performance intricately. This study zeroes in on an airfoil model, subjecting it to a dual scrutiny encompassing empirical investigation and computational simulation. Employing Computational Fluid Dynamics (CFD) analyses executed in ANSYS software, the study prognosticates pressure and velocity patterns for the 2D iteration of the Model 1 airfoil by the National Advisory Committee for Aeronautics (NACA). This exhaustive scrutiny spans across velocities of 10 m/s and diverse angles of attack (-5°, 2°, and 8°). Remarkably, a robust 90% correlation manifests between the outcomes of empirical experimentation and computational simulation. Within the aerodynamic schema of the Horizontal Axis Wind Turbine (HAWT), the 8° angle of attack emerges as the vanguard, distinctly illustrating the pinnacle of optimal pressure distribution and velocity gradient. Noteworthy is the consistent augment in airfoil performance as the blade angle escalates, substantiated by elevated apex velocities and pressures in juxtaposition to the -5° and 2° angles. The findings of this inquiry engender a significant stride in airfoil refinement for the optimization of wind turbine blades, thereby conferring invaluable insights in the realms of blade design, aerodynamic contemplations, and the augmentation of wind turbine performance.

NACA2412 airfoil based method for design and aerodynamic analysis of small HAWT using modified BEM approach

Efficient utilization of wind energy depends on careful selection and suitable design of Wind Turbine (WT) blades. Small scale Wind Turbines (SWT) normally operate in the low range of Angle of Attack (AoA). This makes the task even more difficult for designing and optimization of WT blades. This article deals with an airfoil based computational approach to design the blade for a standalone small scale Horizontal Axis Wind Turbine (HAWT). A procedure has been proposed to find the important parameters and analyze the performance characteristics for a three bladed HAWT operating under the wake rotation. Computational code has been written to find optimum blade profile. Twist angle variation, chord length and other related parameters are determined with the help of program. Comparison between different types of airfoil has been made to figure out the most suitable one. Airfoil selection and design approach are intended to make Wind Turbine blade efficient specially under low range of AoA. Characteristics of the Wind Turbine obtained analytically from this procedure are compared with several other reported earlier in some of the literatures. The result obtained by the proposed procedure is simpler and more efficient than BEM theory – a method normally employed for blade design.

Blade Design and Performance Analysis of Wind Turbine

Abstract: This paper reviews the design optimization of wind turbine blades through investigating the design methods and analyzing the performance of the blades. The current research work in this area include wind turbine blade geometric design and optimization, aerodynamics analysis, wind turbine blade structural design and dynamics analysis. Blade geometric design addresses the design parameters, including airfoils and their aerodynamic coefficients, attack angles, design tip speed ratio, design and/or rated wind speed, rotor diameter, blade aerodynamic shape with chord length and twist distributions, so that the blade achieves an optimum powerperformance. The geometry of the blade is an aerodynamic shape with nonlinear chord and twist distribution, which can be obtained based on the BEM theory with respect to given aerofoil with known aerodynamic coefficients. In terms of blade aerodynamics analysis, there are four types of aerodynamic models which can be used to predict the aerodynamic performance of blades, including blade element momentum (BEM) model, lifting panel and vortex model, actuator line model, and computational fluid dynamics (CFD) model. Among the four, computational fluid dynamics (CFD) model has been used to calculate the aerodynamic effect on the bladeairfoil. Critical Reynolds number and constant wind speed has been considered during analysis under different turbulence models Viz, spallart-almaras, k-epsilon, invicid flow. During investigation it is observed that only k- epsilon showed efficient results than others and 14 degree angle of attack (AOA) is the optimum value at which there is much lift coefficient and minimum drag

Aerodynamic shape optimization of wind turbine blades for minimizing power production losses due to icing

Ice formation on a wind turbine alters the airfoil profiles of the blades and causes degradation in the aerodynamic performance of the wind turbine and the resulting power production losses. Since the blade profile plays a significant role in the icing of a blade, power production losses due to icing can be minimized by optimizing the blade profile against icing. In this study, blade profiles are optimized in order to minimize power production losses. A Gradient based aerodynamic shape optimization method is developed together with the Blade Element Momentum method and an ice accretion prediction tool in order to minimize the power production losses of horizontal axis wind turbines under various icing conditions. In an optimization study performed for the Aeolos-H 30 kW and NREL 5 MW wind turbines exposed to icing conditions up to 1 h, the power loss due to icing is reduced by about 4%.

Ply Parameters Optimization and Strength Reliability Analysis of Wind Turbine Blade

As the critical component of capturing wind energy, the performance and reliability of blade are directly related to the safe, stable operation and service life of wind turbines. The performance of the blade is mainly determined by the ply parameters, so it has important valueto study the optimization method of ply parameters and the analysis method of strength reliability of wind turbine blade.In this paper, the load of a 1.5MW wind turbine bladeunder the DLC1.5g-2 working condition is calculated and its finite element model is established. Combined with engineering practice, the investigation range of ply parameters is determined, the test scheme is designed by using the mixed level uniform experiment method, and the blade strength is analyzed. Based on the polynomial regression analysis method and simulation results, the quadratic mathematical model between the ply parameters and the Tsai-Wu failure factors is established, and the range of ply parameters is optimized by mean value analysis method and interaction analysis method. On this basis, the ply parameters are regarded as random variables, and the structural performance function of blade failure is constructed. The reliability of the blade is predicted by the first-order second-moment method. The results show that the blade is reliable in the range of optimized ply parameters. The work provides the method and technical support for the laminate structure design and optimization of wind turbine blade.

Finite element modeling optimization of wind turbine blades from an earthquake engineering perspective

In a seismic assessment context, wind turbine blades are often excluded from numerical studies mainly due to their complex shape and lack of sufficient data. This tends to suppress their modal effect from the global dynamic response and can potentially influence the reliability of the seismic vulnerability of wind turbines, determined in a traditional manner, i.e., employing the lumped mass approach. This study aims to provide a closed-form solution for deriving the cross-sectional properties of a typical airfoil to further calculate the flapwise, edgewise, and torsional stiffness of a typical wind turbine blade. A genetic algorithm (GA)-based modeling optimization is performed to evaluate the geometric and material parameters that are representative of realistic blades. These parameters are used to achieve the target blade mass, stiffness, and frequencies. The proposed approach results in design solutions (DS) as different combinations of these parameters. Each DS leads to mechanical and modal characteristics that are equivalent for all blade configurations, such as blades with or without webs, with or without structural twist and varying pitch axis locations. These solutions are employed to develop the blades of the RNA in a wind turbine model to test the efficiency of the method. It is suggested that blades should be realistically considered for reliable seismic assessment of wind turbines.

High-order redesign method for wind turbine blade optimization in model test considering aerodynamic similarity

The model test is important in the design and analysis of floating offshore wind turbines. However, the rotor thrust generated by the scaled model blades will be far less than the Froude-scaled value in the wave basin test, which has a significant effect on motion responses of floating offshore wind turbines. Thus, in order to improve the reliability of model tests, it is essential to simulate the rotor thrust accurately based on the aerodynamic similarity. In the present study, four parametric models were developed to define the geometry of model blades and they were integrated separately into the optimization model to reach the design criteria. Considering the weight control, the model blade defined by high-order design method was tested. It was demonstrated that the deviation between the experimental and numerical model blades under the rated condition was very small (only 3.16%). Under the same condition, the model blade with aerodynamic similarity could improve the rotor thrust by 106.33% compared with the Froude-scaled model blade. Simultaneously, high-order redesign method can significantly reduce the blade weight. Thus, the high-order redesign method is considered to be an effective way to eliminate the scale effect in the model tests of floating offshore wind turbines.

Multi‐site aerodynamic optimization of wind turbine blades for maximum annual energy production in East Iran

AbstractAerodynamic optimization of a horizontal axis wind turbine blade is performed for maximizing total annual energy production in three different sites located in the east part of Iran. While most researches have focused on the optimization of wind turbine blades for a specific location or air velocity, the main objective in practical problems is to find the best single design for multiple locations giving the highest energy output. The current paper addresses this issue and shows that multi‐site optimization of wind turbine blades is the key to maximizing energy extraction at multiple sites while reducing the manufacturing costs by proposing one optimum blade for all sites. In order to achieve this goal, the known Riso wind turbine blade is used as the base geometry and is optimized using a modified blade element momentum (BEM) theory and genetic algorithm. The objective function is maximizing sum of energy production at the selected sites. Blade twist and chord length distributions are chosen as design parameters. By running various optimization cases, it is shown that the multi‐site optimum blade has the highest sum of annual energy production by 4.45% increase compared with the Riso wind turbine blade.

Efficient incorporation of fatigue damage constraints in wind turbine blade optimization

AbstractWind turbine design is a challenging multidisciplinary optimization problem, where the aerodynamic shapes, structural member sizing, and material composition must all be determined and optimized. Some previous blade design methods incorporate static loading with an added safety factor to account for dynamic effects. Others incorporate dynamic loading, but in general limit, the evaluation to a few design cases. By not fully incorporating the dynamic loading of the wind turbine, the final turbine blade design is either too conservative by overemphasizing the dynamic effects or infeasible by failing to adequately account for these effects. We propose an iterative method that estimates fatigue effects during the optimization process while quickly converging to the true solution. We also demonstrate an alternate approach where a surrogate model is trained to efficiently estimate the dynamic loading of the wind turbine in the design process. This surrogate model, once trained, was then incorporated in the optimization loop of the wind turbine blade. In contrast to the iterative method, there is significant upfront computational cost to construct the surrogate model. However, this surrogate model has been generalized to be used for different rated turbines and can predict the fatigue damage of a wind turbine with less than 5% error for baseline wind turbines of the same family. These methods can be used instead of the more computationally expensive method of calculating the dynamic loading of the turbine within the optimization routine.

Structure Optimization of Wind Turbine Blade with Winglet using CFD

The wind turbines have restriction on increasing its rotor diameter. Winglets are angled extensions or vertical projections at a wing's trail and are commonly utilized on commercial aircraft in combination with flat airfoils to minimize induced drag and increase lift. Introducing a winglet to the cutting edge of the turbine blade enhances the power generation without extending the intended rotor area. For the aeronautical industry and especially for high-performance sail planes, the winglet structure has been thoroughly examined. Because winglets have been shown to decrease drag and increase wind turbine rotor blade aerodynamic efficiency, it is major to realize and evaluate the method of performance and design enhancement used by previous researchers for this application. It provides a good description and concepts for handling the design process for the application of the wind turbine. The objective of the project is to evaluate turbine blade flow dynamics with winglet and to enhance the efficiency of its physical dimensions. CFD analysis would be go through by altering its physical size and shape with the target of realizing augmented power.

Linear and nonlinear buckling analysis for the material design optimization of wind turbine blades

Purpose The purpose of this paper is to investigate the buckling behavior of the load-carrying support structure of a wind turbine blade. Design/methodology/approach Experimental experience has shown that local buckling is a major failure mode that dominantly influences the total collapse of the blade. Findings The results from parametric analyses offer a clear perspective about the buckling capacity but also about the post-buckling behavior and strength of the models. Research limitations/implications This makes possible to compare the response of the different fiber-reinforced polymers used in the computational model. Originality/value Furthermore, this investigation leads to useful conclusions for the material design optimization of the load-carrying box girder, as significant advantages derive not only from the combination of different fiber-reinforced polymers in hybrid material structures, but also from Kevlar-fiber blades.

Aerodynamic and structural optimization of wind turbine blade with static aeroelastic effects

Abstract With the increasing size of wind turbine blade, the aeroelastic analysis becomes an essential step in the blade design process. The scope of this paper is to investigate the static aeroelastic effects between the fluid–structure interaction and improve the blade performances. First, the rigid and flexible blades are used to analyze the effects of static aeroelasticity on the blade aerodynamic and structural performances through a blade element momentum model coupled with 3D finite element analysis model. Based on this, a multi-objective aerodynamic and structural optimization method is proposed aiming at increasing the annual energy production and reducing blade mass, key parameters of the blade are employed as design variables, and various design requirements including strain, deflection, vibration and buckling limits are considered as constraints. Finally, a commercial 1.5 MW wind turbine blade is applied as a case study, and the optimization results show great improvements for the aerodynamic and structural performances of the blade.

Adjoint-Based High-Fidelity Structural Optimization of Wind-Turbine Blade for Load Stress Minimization

A high-fidelity multidisciplinary modeling and optimization capability is employed for optimization of structural properties of the 13 m Scaled Wind Farm Technology Facility wind-turbine blade of Sandia National Laboratories. This involves coupling a Reynolds-averaged Navier–Stokes fluid dynamics solver with a structural finite element solver. The exact sensitivities of performance objectives are obtained using the discrete adjoint method. For each of several load cases, the composite fiber angles throughout the internal structure of the blade are optimized to minimize a scalar stress parameter that correlates with the accumulation of fatigue damage. Three main types of loads regularly experienced by a wind-turbine blade are identified: aerodynamic loads, centrifugal loads, and gravitational loads. Static structural optimization is performed with the blade under centrifugal and aerodynamic loads, and dynamic optimization with the blade under gravitational loads. Then, static and dynamic optimizations are performed again with all combined loads present. A 18–60% reduction in the driving stress for fatigue is seen in after optimization.

一般化翼素運動量理論の拡張:拘束流中の風車ブレード形状最適化における翼端・翼根損失の影響

一般化翼素運動量理論の拡張:拘束流中の風車ブレード形状最適化における翼端・翼根損失の影響

Structural gradient based sizing optimization of wind turbine blades with fixed outer geometry

In this work the mass of a 73.5 m offshore wind turbine blade is minimized while considering manufacturing constraints, tip displacement, buckling, and static strength criteria when subject to an extreme load envelope consisting of 12 load directions. The gradient based sizing optimization takes offset in the outer geometry and loading from a commercial 73.5 m wind turbine blade where the manufacturing mold should be re-used and hence the outer geometry is kept constant. A solid-shell finite element model of the full blade is used as basis for the optimization. The blade is divided into patches and thicknesses of ply-groups (groups of contiguous plies with the same material and fiber orientation) are used as design variables. The design variables are assumed continuous in the optimization phase. Sequential linear programming (SLP) is used to solve the problem with semi-analytical gradients. In the post-processing phase the lay-up is refined and ply-group thicknesses are rounded to a whole number of plies. The gradient based sizing optimization results in a reduced mass and many active constraints across multiple load directions while the post-processing ensures manufacturability.

A SCADA data mining method for precision assessment of performance enhancement from aerodynamic optimization of wind turbine blades

The target of improving efficiency of wind kinetic energy extraction has stimulated a certain attention to wind turbine retrofitting. This kind of interventions has material and labor costs and producible energy is lost during installation. Further, the estimation of the energy enhancement is commonly provided under the hypothesis of ideal conditions that can be very different from real ones. Therefore, a precise estimation of performance improvement is fundamental. In this work, a SCADA-based method is formulated for estimating the improvement in energy production of multi-megawatt wind turbines, sited in Italy in a very complex terrain. The blades of one wind turbine in the farm have been optimized by installing vortex generators and passive flow control devices. An Artificial Neural Network (ANN) model is employed: the output is the power of the retrofitted wind turbine and the inputs are the powers of some reference nearby wind turbines. The production increase is estimated by observing how the difference between simulated and measured power output changes after the installation of the aerodynamic upgrade. The average improvement is estimated as the 3.9% of the total energy produced below rated power.

Aero-structural optimization of wind turbine blades using a reduced set of design load cases including turbulence

Modern wind turbine aero-structural blade design codes generally use a smaller fraction of the full design load base (DLB) or neglect turbulent inflow as defined by the International Electrotechnical Commission standards. The current article describes an automated blade design optimization method based on surrogate modeling that includes a very large number of design load cases (DLCs) including turbulence. In the present work, 325 DLCs representative of the full DLB are selected based on the message-passing-interface (MPI) limitations in Matlab. Other methods are currently being investigated, e.g. a Python MPI implementation, to overcome the limitations in Matlab MPI and ultimately achieve a full DLB optimization framework. The reduced DLB and the annual energy production are computed using the state-of-the-art aero-servo-elastic tool HAWC2. Furthermore, some of the interior dimensions of the blade structure are optimized using the finite-element based cross-sectional analysis tool BECAS. The optimization framework is applied to redesign the NREL 5 MW wind turbine blade to obtain improvements in rotor performance and blade weight.

Structural optimization of wind turbine blades with ring shear webs

The aim of this paper is to present an optimized structure for the design of wind turbine blades. It sets up a forced blade model with ring shear webs and deduces the equations for the inertia moment Iy of airfoil section, the maximum stress σmax and the compression ΔD of airfoil relative thickness. Then, the model and the equations are applied to one 750 kw wind turbine. By MATLAB software, the changing trends of the inertia moment Iy, the maximum stress σmax, and the compression ΔD, respectively, along with the ratio e of the inner chord length to the outer and the blade span x are gained. It is concluded that the bending strength around the blade root increases greatly. It also indicates that the bending strength of blades with ring shear webs is almost the same as the blades with solid shear webs when the ratio e is set as 0.4, and also the use of ring shear webs in wind turbine blade structure leads to lighter blades.

Integrated free‐form method for aerostructural optimization of wind turbine blades

AbstractA typical approach to optimize wind turbine blades separates the airfoil shape design from the blade planform design. This approach is sequential, where the airfoils along the blade span are preselected or optimized and then held constant during the blade planform optimization. In contrast, integrated blade design optimizes the airfoils and the blade planform concurrently and thereby has the potential to reduce cost of energy (COE) more than sequential design. Nevertheless, sequential design is commonly performed because of the ease of precomputation, or the ability to compute the airfoil analyses prior to the blade optimization. This research compares 2 integrated blade design approaches. The precomputational method combines precomputation with the ability to change the airfoil shapes in limited ways during the optimization. The free‐form method allows for a complete range of airfoil shapes, but without precomputation. The airfoils are analyzed with a panel method (XFOIL) and a Reynolds‐averaged Navier‐Stokes computational fluid dynamics method (RANS CFD). Optimizing the NREL 5‐MW reference turbine showed COE reductions of 2.0%, 4.2%, and 4.7% when using XFOIL and 2.7%, 6.0%, and 6.7% when using RANS CFD for the sequential, precomputational, and free‐form methods, respectively. The precomputational method captures most of the benefits of integrated design for minimal additional computational cost and complexity, but the free‐form method provides modest additional benefits if the extra effort is made in computational cost and development time.

Meta-heuristic multidisciplinary design optimization of wind turbine blades obtained from circular pipes

Aim of this paper is to present a methodology useful to optimize the geometry of the blades of a small-size wind turbine which are obtained from a circular pipe: an optimal chord distribution and airfoil sweep can be obtained with a proper cutting path. A strong reduction in manufacturing costs and time can be achieved for blades which are a critical element in wind turbine systems, especially in case of renewable plants in developing countries. An algorithm has been developed to obtain the shape of the blades and wind turbine performances are computed by the Blade-Element Method, due to its low computational simplicity; the XFoil tool has been used to compute the aerodynamic of the blades. Heuristic algorithms have been applied to obtain a feasible design solution assuring the best efficiency of the wind turbine. Also structural considerations are kept into account to provide a feasible configuration able to withstand the forces acting on the rotating blades. Results obtained suggest that an optimal design of such a kind of blades can be obtained thanks to this methodology. The mathematical framework developed for the optimization is efficient and the heuristics algorithms allow the convergence to feasible configurations. The computing time is compatible with a practical application of the method also in industries.