Horizontal Axis Wind Turbine Blade Research Articles

Parametric study of flapwise and edgewise vibration of horizontal axis wind turbine blades

In this paper, flapwise and edgewise vibrations of a horizontal axis wind turbine (HAWT) blade are studied. Rayleigh-Ritz method is used in which; orthogonal mode functions of the Euler-Bernoulli beam having fixed-free boundary are introduced into the Lagrange function and then the dynamic equations are derived. Effect of gravity, pitch angle, centrifugal stiffening, and rotary inertia are considered. Nondimensional equations are obtained by defining nondimensional parameters like; natural frequency, blade rotation, slenderness ratio, and simple pendulum frequency. The stiffness term of the natural frequency has two speed dependent elements and it is shown that, for small pitch angles, flapwise natural frequencies of the blade are increased by the increasing blade speed while the edgewise natural frequencies of the blade are decreased with the increasing blade speed. Pitch angle values ranging from 0° to 15° has negligible effect on the nondimensional natural frequencies of the blade up to the nondimensional blade speed of 4. Since the natural frequencies are the function of the blade speed, rotor critical speeds should be calculated with Campbell diagrams. Vibrational response of the blade tip to the gravity is dominant and much greater than that of the wind speed in the edgewise and flapwise vibration.

Design and Analysis of Horizontal Axis Wind Turbine (HAWT) Blades Using CFD

Abstract: Within the current years wind power is extensively taken into consideration and applied as one of the most promising renewable electricity assets. In the recent studies have a look at, aerodynamic analysis of horizontal axis turbine is achieved with the aid of using cfd. Blades which can be often possible for industrial grade wind turbines embody a directly span-wise profile in conjunction with airfoil fashioned go sections. Wind tunnel test is applied in order to check aerodynamic efficiency wind turbine blade. The goal of this study is to design a wind turbine. The layout manner includes the choice of the sun machine for max efficiency and wind turbine kind and the determination of the blade airfoil, pitch attitude distribution along the radius, and chord duration distribution along the radius. The pitch angle and chord period distributions are optimized primarily based on conservation of angular momentum and principle of aerodynamic forces on an airfoil. Blade element momentum (BEM) principle is first derived then used to conduct a parametric observe to be able to determine if the optimized values of blade pitch and chord period create the maximum green blade geometry. This work includes a discussion of the most important parameters in wind turbine blade layout to maximize efficiency. Keywords: Wind Turbine, HAWT, BEM Theory, Parametric Study, Maximization of efficiency etc.

Bionic coupling design and aerodynamic analysis of horizontal axis wind turbine blades

AbstractWith millions of years of evolution, owls have developed many excellent characteristics in terms of their flight. The speed of an owl in flight is similar to the relative speed of the blade of a small wind turbine with respect to air. Therefore, the owl wing airfoil is selected as the design airfoil of the wind turbine blade to reduce the flow separation under low Reynolds number. In this study, we analyze an owl wing‐section airfoil and the non‐smooth leading‐edge shape of an owl's wing, and implement an orthogonal optimum design to optimize the wavelength and amplitude of the non‐smooth leading edge. We extract the cross‐sectional features of the airfoil and the non‐smooth leading‐edge shape of the wing. Based on the orthogonal optimum design results, we determine the optimal combination of the wavelength, amplitude, and airfoil, and then design a horizontal‐axis wind turbine blade through bionic coupling. The flow field at different tip speed ratios (TSRs) is simulated using the turbulence model at the rated wind speed. The results show that the power coefficient () of the bionic wind turbine at a high tip speed ratio is 17.7% higher than that of the standard type. Furthermore, we analyze the operation of the turbine at TSRs of 2 and 5. At a high TSR, the leading edge bulge of the bionic wind turbine blade can change the flow direction distribution of the airflow on the blade surface, make the airflow to adhere to the suction surface, and then reduce the stall area on the suction surface of the blade. Thus, the wind turbine produces higher torque, thereby generating higher power.

Investigation on aerodynamic performance of horizontal axis wind turbine by setting micro-plate in front of the blade leading edge

Under the pressure of conventional energy emergency and global environmental degradation, wind energy has been developed and utilized as an important energy source since 1973. However, flow separation occurs on the surface of horizontal axis wind turbine blades under high angle of attack, which reduces the utilization rate of wind energy. To address this problem, a method of setting micro-plate in front of the blade leading edge of the NREL Phase VI wind turbine is proposed, and the effects of the micro-plate at different positions and different plate widths on the aerodynamic performance of the wind turbine are investigated. The results show that distance between the micro-plate and the blade leading edge from the blade thickness direction and the chord length direction have significant effects on the aerodynamic performance of the blade, there is a position where the flow separation control effect is best. While in the same position, the control effect of micro-plate on the flow separation is different with different plate widths, and there is an optimal plate width at certain wind speeds, which makes the flow control effect the best.

Influence of Reynolds number consideration for aerodynamic characteristics of airfoil on the blade design of small horizontal axis wind turbine

ABSTRACT Airfoil’s aerodynamic characteristics are vital for the design and performance evaluation of wind turbine rotor blades through blade element momentum theory. Generally, the airfoil’s aerodynamic characteristics are evaluated at an approximated fixed Reynolds number. However, during a typical operation of a wind turbine, the Reynolds number varies along the length of the blade as well as with wind speed. Since airfoil’s aerodynamic characteristics are dependent on Reynolds number, inadequate consideration of Reynolds number in blade element momentum theory may result in discrepancy in an optimum design and performance evaluation. In the present work, the influence of inadequate consideration of Reynolds number on design and performance evaluation of a small horizontal axis wind turbine blade is studied. For the study, a wind turbine blade design with various design considerations, including a range of design tip speed ratio (5, 6, 7, and 8) and a range of inadequately approximated fixed (i.e., 0.5, 0.75, 1.00, and 1.25 million) and operational Reynolds number for aerodynamic characteristics of the airfoil, is considered. The study suggests that inadequate fixed Reynolds number consideration for blade design and performance evaluation can result in blade solidity as high as 17.1% with respect to blade design considering operational Reynolds number consideration and discrepancy in power coefficient prediction as high as 3.6% with fixed Reynolds number consideration for aerodynamic characteristics of the airfoil.

Long-term fatigue reliability enhancement of horizontal axis wind turbine blade

The enhancement of fatigue life of ultra-large horizontal axis wind turbine blade using longitudinal stiffening is the theme of this work. For this purpose, a tendon made of shape memory alloy is used along the longitudinal axis of blade, which is modelled in aeroelastic spinning finite element framework. The force developed in the tendon acts against the deformation where the material is modelled using Liang and Rogers constitutive relationship along with the principles of thermodynamics. The fatigue design follows the guidelines provided in internationally recognised codal provisions. The blade responses are simulated using aeroelastic loads obtained from blade element momentum theory. These dynamic responses are utilised to evaluate the longitudinal stress in the extreme fibre over the blade profile. Then, short-term and long-term damages are evaluated using rainflow matrix obtained from these stresses. Finally, the reliability of blade against fatigue failure is investigated. The numerical analysis presented in this study clearly demonstrates the performance of the longitudinal stiffening in combination with pitch angle on the fatigue life of the blade.

Structural design of offshore wind turbine blade spars

The structural design of spars for horizontal axis wind turbine blades to achieve satisfactory levels of performance starts with the knowledge of aerodynamic forces acting on the blades. The present paper proposes a comparative study of the geometries of three spars designed for a 48 m long composite blade. The spars are evaluated under compression, bending loads as well as on free vibration. Different Subroutines have been developed and coupled with Finite Element Analysis (FEA) software to analyze the mechanical performances and the qualities of each one of the three designed spars. In other words, it seeks not only to define the behavior and response of each one of the spars and the effect of composite materials on the improvement of the structure stiffness and weight, but also to determine the suitable spars type for the wind turbine blade and the results shows that the Box spars offers a compromise of the main parameters.

Aerodynamic Optimization of a Swept Horizontal Axis Wind Turbine Blade

Abstract The aerodynamic shapes of the blades are still of high importance and various aerodynamic designs have been developed in order to increase the amount of energy production. In this study, a swept horizontal axis wind turbine blade has been optimized to increase the aerodynamic efficiency using the computational fluid dynamics method. To illustrate the technique, a wind turbine with a rotor diameter of 0.94 m has been used as the baseline turbine, and the most appropriate swept blade design parameters, namely the sweep start-up section, tip displacement, and mode of the sweep have been investigated to obtain the maximum power coefficient at the design tip speed ratio. At this stage, a new equation that allows all three swept blade design parameters to be changed independently has been used to design swept blades, and the response surface method has been used to find out the optimum swept blade parameters. According to the results obtained, a significant increase of 4.28% in the power coefficient was achieved at the design tip speed ratio with the newly designed optimum swept wind turbine blade. Finally, baseline and optimum swept blades have been compared in terms of power coefficients at different tip speed ratios, force distributions, pressure distributions, and tip vortices.

Aeroelastic stability analysis and failure damage evaluation of wind turbine blades under variable conditions

ABSTRACT Failure during the start and brake processes of a 1.5 MW horizontal axis wind turbine blade was examined using a measured wind field with fluid-structure coupling. The maximum blade displacement and stress with angular acceleration during the start process were 7.14% and 16.27%, respectively, larger than those without acceleration, whereas during braking they were 37.71% and 26.96% larger, respectively, without acceleration. Further, angular acceleration had a greater impact on the second-order frequency of vibration than the first-order, significantly impacting the braking process. The maximum dynamic stress and amplitude of the blades during starting were 4.35 MPa and 0.56 m, and during braking were 35.86 MPa and 3.13 m, respectively. Based on drone images of the blades, several failure modes were identified. This research will provide key inspection area guidance for employing drones to inspect blades to improve inspection efficiency. A large amount of damage images are collected and classified into damage levels, and an image processing system are established, which can quickly identify damage characteristics of the blade and export the inspection report quickly and accurately. Through a large number of drone detection experiments, this technology has a wide range of application prospects and extremely high efficiency.

One step ahead adaptive control technique featured by fuzzy-based least square estimator for wind systems

The present paper proposes the application to a wind system of the One Step Ahead control scheme featured by a Fuzzy-based Least Square Estimator. The considered wind system power generation supplies an electrical load disconnected from the power supply grid. It is composed of a three bladed horizontal-axis wind turbine which drives a synchronous generator by means of gearbox: the mathematical model for both the horizontal-axis wind-turbine and the synchronous generator will be briefly outlined. The adaptive nature of the One-Step-Ahead control algorithm relies on providing consistent estimation of the controlled system. This is achieved by means of a Least Square Algorithm that is able to provide a good estimation of a linear discrete time model of the controlled system, nevertheless its convergence rate reduces very quickly. For this reason, Least Square Algorithm needs a resetting strategy, which allows the achievement of a compromise between estimation accuracy and convergence rate. This not only represents a very problem-dependent issue but also introduces weaknesses in term of control tracking errors, which in turns needs an extra control contribution (integral correction). The proposed Least Square Algorithm enhancement overcomes these issues managing differently the estimation accuracy and the convergence rate. In the Results section, the achievements of the application of the One-Step-Ahead algorithm to the wind system will prove the reliability of the suggested enhanced control technique.

Experimental investigations and aerodynamic shape optimization of small horizontal-axis wind turbine blades

This study aims to optimize and investigate small horizontal-axis wind turbine blades at low wind speeds. The objective of this study is to explain the design method based on BEM theory for 0.2 m blade rotors with constant, variable, and linear chord with twisted blade geometry. MATLAB and Xfoil programs were used to apply BEM principles on wind turbines with SG6043 airfoil. Numerical and experimental studies were carried out to examine the impact of rotor solidity values from 0.057 to 0.207 and the number of blades from 3 to 7. The experimental blades were developed using a 3D printing additive manufacturing technique. The rotors were investigated in an open wind tunnel at wind speeds ranging from 2 to 8 m/s. The initial investigation range included tip speed ratios from 2 to 8 and angles of attacks from 2° to 20°. Subsequently, these parameters were varied in Matlab and Xfoil software to optimization and investigate the power coefficient, blade geometry, number of blades, and blade pitch angle. It was found that a rotor solidity of 0.055–0.085 displayed better performance.

Genetic algorithms for the design and optimization of horizontal axis wind turbine (HAWT) blades: A continuous approach or a binary one?

The continuous and the binary techniques are the main types of genetic algorithms that could be employed for an optimization problem. The study investigates the robustness and accuracy of each technique for the wind turbine blades design and optimization problem. For that purpose, the geometry of the blade was designed for the maximization of the output power, the desirable goal of the blade design. The design variables consist of the distribution of the chord and twist along the blade. Results indicate that the continuous genetic algorithm outperforms the binary one from the standpoint of the accuracy and also the computational time. However, the use of uniform crossover could improve the convergence rate of the binary genetic algorithm. Moreover, the sensitivity analysis of the applied genetic algorithms with respect to the population size and the mutation rate was performed to find the appropriate values for those parameters. The outcomes emphasized that adopting a small number of population size together with a large number of generations could speed up the convergence rate of the problem. Also approved in the study was the efficiency of the so-called “Superblade” operator which improved the convergence rate of the algorithm and resulted in the powerful blades.

2D optimization of a Small Horizontal Axis Wind Turbine blade using flow control techniques

In this work, the optimization of the efficiency of a small horizontal axis wind turbine (SHWT) blade segment is presented. Typically, SHWTs have a radius of 1.5 to 3.5 m and a hub height of around 15 m from the ground. SHWTs operate in a relatively small Reynolds numbers range (up to 1.5x106) and are installed inside the atmospheric boundary layer. This operational environment is characterised by volatile air flow, making the flow over the blade prone to separation. In order to counter this flow behavior, a set of flow control techniques is introduced and studied. These techniques control the flow, either passively, solely by the inclusion of blade add-ons, or actively, by adding energy to the boundary layer. More specifically, two passive flow control techniques and one active flow control technique are modelled and tested on a wind turbine blade segment. The passive techniques implemented in this study are based on the use of vortex generators and tubercles. Vortex generators are small vanes attached vertically to the lifting surface and are widely used in aerospace applications with varying degrees of success. Tubercles, which is a novel flow control technique, are sinusoidal modifications of the blade’s leading edge. The original concept has been inspired from the characteristic flipper of the humpback whale (Megaptera Novaeangliae). Regarding the active flow control technique, a dielectric barrier discharge (DBD) plasma actuator (PA) is used, a technique that adds momentum on the local flow, close to the blade’s surface, by ionizing the air. The impact on the blade aerodynamic efficiency for each technique are evaluated and presented. The results from this evaluation show that flow control techniques can offer a considerable benefit to SHWT by improving the blade’s aerodynamic characteristics, i.e. by increasing the blade lift-to-drag ratio and thus, improving their critical performance efficiency factor.

Performance estimation and redesign of horizontal axis wind turbine (HAWT) blade

The present global energy crisis has pushed the human race to its limit in search of alternative sources of energy. Wind turbine technology has seen continuous developments ever since the humankind has been on the lookout for harnessing the wind energy. The modern design analysis tools and the emergence of new materials have enabled the development of state-of-the-art wind turbines. The main power-producing component in the turbine is none other than the blade itself which has undergone a major design improvement in the recent past. The Present work comprises of re-design of a composite blade of an experimental Horizontal-axis Wind turbine with appropriate structural modifications to reduce its weight and hence improving it efficiency. A load generation code V BLADE was developed in C-language for calculating the design wind loads on the turbine blade. An optimized and efficient blade design with spar-rib construction was arrived satisfying the power requirements and structural design criteria through structural optimization by deploying FEA SW satisfying static and buckling design constraints. The optimization resulted in a substantial blade weight reduction of thirty-nine present.

Analisis Performa Bilah Taperless Dengan Airfoil NACA 4412 pada Horizontal Axis Wind Turbine TSD 500 di PT Lentera Bumi Nusantara

Abstract: The use of wind energy in Indonesia is currently still low due to the average wind speed in the Indonesian territory ranging from 3 m / s to 11 m / s, making it difficult to produce electrical energy on a large scale. However, the potential for wind in Indonesia is available almost all year round, making it possible to develop small-scale power generation systems. Innovations in modifying windmills need to be improved so that in low wind speed conditions it can produce electrical energy. Therefore, a HAWT (Horizontal Axis Wind Turbine) blade design was made using a NACA airfoil which has a high Cl / Cd value and produces 500 W of power at wind speeds of 1 - 11 m / s. The research was conducted in 3 stages. The first calculation phase is to determine the radius, chord and twist of the blade. The two stages of the initial blade design were simulated using QBlade software to determine the NACA airfoil being used and to determine the performance coefficient and the resulting power. The three stages of blade design use Solidworks software which produces a 3D blade design. The design results produce a HAWT blade with a taperless NACA 4412 airfoil with blade radius of 1 m, chord width 0.12 m, and twist angle of 5.08 ° - 12.08 °. At a wind speed of 10 m / s, the blade has a maximum Cp of 52%, a maximum power of 1010 W at an angular speed of 450 rpm, a minimum power of 85 W at an angular speed of 95 rpm. The average power produced is 547.5 W. Field test results of Taperless NACA 4412 blades. The results of the field testing are 585.58 W of maximum charge and an average charge of 30.24 W, with the resulting power of 725.55 Wh. Keywords: Blade, Taperless, NACA 4412,Wind Turbine

Kriging Surrogate-Based Genetic Algorithm Optimization for Blade Design of a Horizontal AxisWind Turbine

Horizontal axis wind turbines are some of the most widely used clean energy generators in the world. Horizontal axis wind turbine blades need to be designed for optimization in order to maximize efficiency and simultaneously minimize the cost of energy. This work presents the optimization of new MEXICO blades for a horizontal axis wind turbine at the wind speed of 10 m/s. The optimization problem is posed to maximize the power coefficient while the design variables are twist angles on the blade radius and rotating axis positions on a chord length of the airfoils. Computational fluid dynamics was used for the aerodynamic simulation. Surrogate-assisted optimization was applied to reduce computational time. A surrogate model called a Kriging model, using a Gaussian correlation function along with various regression models, was applied while a genetic algorithm was used as an optimizer. The results obtained in this study are discussed and compared with those obtained from the original model. It was found that the Kriging model with linear regression gives better results than the Kriging model with second-order polynomial regression. The optimum blade obtained in this study showed better performance than the original blade at a low wind speed of 10 m/s.

Shape memory alloy‐based centrifugal stiffening for response reduction of horizontal axis wind turbine blade

The aim of this study is to reduce the deformation of large horizontal axis wind turbine blades using shape memory alloy (SMA)-based centrifugal stiffening. A discrete model considering dominant modes of the tower, drive train and blades is developed in this study to demonstrate the performance of the proposed stiffening strategy. Here, super-elastic behaviour of SMA is characterized by Graesser-Cozzarelli model. Aerodynamic loads acting on the blades are evaluated using blade element momentum theory. The response is simulated using aerodynamic damping, which is estimated in each mode of vibration. Numerical results presented in this paper clearly show the significance of the proposed SMA-based stiffening to reduce blade vibration. Sensitivity analysis is also carried out to demonstrate the performance envelop of the proposed stiffening strategy over the operational range of the benchmark 5-MW wind turbine. The study clearly highlights the performance enhancement in terms of deformation in two orthogonal directions and design in terms of longitudinal stress that ultimately improve the serviceability of the blade.

Numerical optimization of horizontal-axis wind turbine blades with surrogate model

Wind energy is a widely used and developed the renewable energy, which has developed rapidly. At present, the design of the horizontal axis wind turbine blade mainly used Blade Element Momentum theory. In this paper, an optimization method of the wind turbine blade was proposed for improving the output power. The local twist angles of the blade were optimized. This method combined the surrogate model and the numerical simulation methods. The kriging surrogate model was selected and the next calibration point was chosen by the efficient global optimization algorithm. In this paper, the aerodynamic performances of the optimized blades were discussed in detail and obtained by the numerical simulation method. It was shown that the wind power coefficients and the output powers of the optimized blades were increased. The wind power coefficients of two optimized blades were increased by 4.83% and 3.44%, respectively. The optimized blades were able to capture more kinetic energy from the wind, but the optimized blades were subjected to a greater structural load. The thrust and torque coefficients maintained an increasing tendency for the optimized blades.

Structural optimization of a horizontal axis wind turbine blade made from new hybrid composites with kenaf fibers

This manuscript presents a continuation of a previous work of the same authors that aims to optimize the materials of wind turbine blades using natural fiber through a hybridization technique. This new conception consists of introducing kenaf fibers into a hybrid composite material initially made with synthetic fibers. Firstly, a detailed analysis was performed to optimize the aerodynamic shape of the wind turbine blade while maintaining an optimal aerodynamic performance. Secondly, ANSYS® Computational Fluid Dynamics (CFD) was used to calculate the aerodynamic parameters needed later in the structural justification. Finally, the blade geometry was imported to PATRAN® software within the objective of establishing a deep analysis of the blade structure taking into account the new combination of the three kinds of fibers: Carbon, glass and kenaf fibers. This fibers combination consists of a skin blade composed with kenaf and glass fibers, a spar cap made of carbon and glass fibers and a spar web made entirely with glass fibers.Compared to the non-optimized model, an evaluation based on materials resistance, weight and cost savings, has shown a weight saving of 40%, a material cost saving of 67% and a tip deflection of about 17% lower than the allowable threshold.

Direct numerical simulation of transitional boundary layers on a horizontal axis wind turbine blade

In boundary layer flow around rotating machines, a radial (or cross-flow) velocity exists due to Coriolis and centrifugal forces. This velocity component can be of great importance for laminar-turbulent transition. A series of direct numerical simulations (DNS) are performed to study the boundary layer flow transition on a rotating Horizontal Axis Wind Turbine blade. To quantify the effect of blade rotation, results are compared with that from airfoil DNS, where the section is taken from 3D blades and does not rotate. It is shown that the rotation gives rise to a small radial velocity and slightly modifies the shape of unstable waves. However, the transition location and mechanism of 3D blade boundary layer flow resemble 2D flow for the investigated case.