Vertical Axis Wind Turbine Blade Research Articles

Design and fabrication of NACA 0018 straight bladed vertical axis wind turbine

The most important advantage in generation of electric power using renewable sources of energy, like wind, are the non availability of toxic exhaust emission products, highly uncluttered and the infinite presence of wind that is finally transformed into electricity. The generation and utilization of wind has been considered as one of the mature and cost effective resources among the various available renewable energy technologies. A wind turbine is a rotating machine that is converting the winds kinetic energy initially to mechanical energy, which finally getting converted into electric power. The wind turbines basically are of two types, i.e. Horizontal Axis Wind Turbine (HAWT) and Vertical Axis Wind Turbine (VAWT). The main point of difference between the two is the position of their axis of rotation. When wind blows over the VAWT, only a fractional part of the blades generates the torque whereas the remaining parts simply rotate. The end result of this is a comparably reduced efficiency in power generation. Here, a miniature Darrieus type VAWT with straight blade - NACA 0018 Airfoil, is designed and fabricated so as to develop maximum possible power output. The blades are designed in way were majority of the air covers majority of blade surface area and thus rotating it at its maximum possible speed. The results shows that the system we developed could produce power of 23.45 watts, with blades designed for aspect ratio of 0.24. This is the maximum possible result that can be attained for this dimension. The entire system is made of strong material so that it could also withstand high wind speed and high energetic wind possible.

Structural analysis of an offshore vertical axis wind turbine composite blade experiencing an extreme wind load

The vertical axis wind turbine (VAWT) configuration has many advantages for an offshore wind turbine installation. The VAWT is omnidirectional and its rotating mechanical components can be placed close to sea level. In this paper, the structural analysis of a VAWT blade structure subject to a critical load case was investigated with two methods, an analytical model and a finite element (FE) model. It was shown that the utilisation of a composite blade topology can resist the induced flapwise loading and the material strains were contained within their allowable limits. The analytical approach was demonstrated to be a quick and accurate technique to compute the composite blade strain distribution when compared to the FE model results.

Design and Analysis of Vertical Axis Wind Turbine Blade

Design and Analysis of Vertical Axis Wind Turbine Blade

A Note on the Decomposition of Aerodynamic Forces Induced by A Wind Turbine Flaps

ABSTRACTIn this study, the aerodynamic characteristics of a vertical-axis wind turbine blade coupled with a high-lift device, such as the Gurney flap at the trailing edge, are investigated. For numerical analysis, the force element theory is used to understand how the Gurney flap influences the force evolution of the lift-type vertical-axis wind turbine. This study shows that the lift and drag can be respectively approximated into four elements, which are induced by volume vorticity, rotational velocity, angular acceleration and surface friction of the flow around the blades. Based on the perspective of the force element theory, the present simulation provides a clear picture of how the Gurney flap influences the formation of the aerodynamic force elements during a rotational cycle for a vertical-axis wind turbine. Simulation results show that the contributions mainly result from the surface vorticities, the rotational acceleration of the airfoil, and the acceleration of the surface.

Design, Fabrication and Performance Evaluation of Hybrid Vertical Axis Wind Turbine

Vertical axis wind turbines (VAWT) have attracted a lot of attention recently as an efficient tool in harnessing wind energy; however these types of wind turbine are faced with some challenges which affect their overall performance. The Darrieus rotor has difficulty to self-start by itself while the Savonius rotor has low efficiency. The performance of these turbines can be improved by combining the two VAWTs as one system. This paper presents the design of a hybrid VAWTs turbine. The Hybrid VAWTs combines the Darrieus rotor and the Savonius rotor as a single system to produce a high starting torque and enhanced efficiency. The Savonius rotor is placed at the centre of the three vertical blades of the Darrieus H-rotor to form the hybrid VAWTs. The hybrid VAWT was tested at four different wind speed i.e. V = 4.80 m/s, 4.50 m/s, 4.30 m/s and 3.90 m/s respectively. The performance of the hybrid VAWT was compared with the conventional straight bladed VAWT under similar experimental conditions. The obtained results showed that there is substantial improvement in the self-starting ability and coefficient of power (Cp). At V = 4.80 m/s, the Cp values for hybrid VAWT increased by 92% compared to straight bladed H-rotor VAWT. Similar improvement was also observed at wind speed of V = 4.50 m/s, 4.30 m/s, and 3.90 m/s where the Cp values increases by 71%, 10%, and 67% respectively compared to the straight bladed H-rotor.

Performance Evaluation of a 1 kW Variable Pitch-Straight Blade Vertical Axis Wind Turbine

Abstract This research work represents a study of the design, analysis, and experimental study of a 1 kW variable pitch-straight blade vertical axis wind turbine (VAWT) using natural fiber reinforced composite. Wind turbine which is an emerging technology is of great interest for researchers nowadays. The VAWT was chosen for this study because of its numerous advantages over horizontal axis wind turbine (HAWT). A new concept of variable pitch was implemented by the introduction of a pitching mechanism associated with the turbine blades which helps the blade to maximize the generation of torque and power. For this purpose, the straight blade H-rotor design was chosen. The analytical calculations were performed for variable pitch and the fixed pitch blade followed by the computer aided design modeling of the rotor exhibiting the variable pitching mechanism. Computational fluid dynamics (CFD) analysis of the blade at the azimuth position of 0–360 deg was performed and the CFD results were imported into static structural module of ansys for the finite element analysis of the blade. The blade was 3D-printed at a reduced scale and tested in a wind tunnel for aerodynamic properties including lift, drag, and aerodynamic forces. A comparison was done between the analytical, software, and experimental values. Furthermore, basalt fiber which is a natural fiber was used as the material for the turbine blade and analysis was performed to obtain high strength to weight ratio of the composite material. The structure was analyzed under the damage tolerance study to determine for how long the structure can bear damage. The experimental results showed a good agreement with the analytical and numerical values. The introduction of the variable pitching mechanism resulted in an increase in the cumulative torque as compared with the fixed pitching mechanism which in turn enhanced the resulting power.

The effect of gurney flap on flow characteristics of vertical axis wind turbine

Recently, the Gurney Flap (GF) has been used to improve the performance of Horizontal Axis Wind Turbine (HAWT) by enhancing its lift coefficient. Compared to HAWT, research on GF application for Vertical Axis Wind Turbine (VAWT) is very limited. Moreover, most works studied a GF geometry attached to the trailing edge of a stationary airfoil, without considering the rotating effect experienced by VAWT. For this reason, a three-straight-bladed VAWT rotating blade with GF is studied by transient RANS simulation together with a stress-blended eddy simulation (SBES) turbulence model to investigate the GF height effect and the flow characteristics near the blade trailing edge. Results have shown that by introducing the blade rotating, an optimum GF height is found to be 3% of the blade chord, slightly higher than 2% chord in a stationary airfoil case. In addition, the presence of GF can delay deep stall of VAWT blades, thus eliminating negative instantaneous moment coefficient and improving the turbine performance.

Low wind speed aerodynamics of asymmetric blade H-Darrieus wind turbine-its desired blade pitch for performance improvement in the built environment

An asymmetric blade vertical-axis wind turbine (VAWT) is one of the emerging technologies for harvesting power in the built environment, which has low wind speed. Although asymmetric blade improves VAWT’s performance, the effect of blade pitch angle on its design is hardly ascertained. In this paper, unsteady 2D Reynolds-averaged Navier–Stokes CFD simulations are carried out to investigate the effect of blade pitch angle on the aerodynamic performance of a NACA 63-415 asymmetric blade H-Darrieus VAWT at a low wind speed of 6.0 m/s. Its detailed flow physics at different operating and pitch angle conditions is investigated, and important performance insights are obtained to elucidate its desired blade pitch for performance improvement. The present study shows that positive pitch angle (+ 5°) improves the turbine performance in upwind position, whereas negative pitch angle (− 5°) augments the turbine performance in downwind position as well as causes less wake effect than positive pitch angle. Further, optimal pitch angle (+ 5°) is found out at which the maximum power coefficient of 0.271 is obtained for an operating tip speed ratio 2.4. The present study delineates how desired blade pitch improves the performance of asymmetric blade VAWT for sustainable power generation in the built environment.

Optimization of the power output of a vertical axis wind turbine augmented with a flat plate deflector

Power performance of a straight blade vertical axis wind turbine augmented with a flat plate deflector was studied. A design of experiment method based on Taguchi’s L16 orthogonal array was employed to optimize the position, orientation, and dimensions of the deflector. Five parameters, including the horizontal distance of the top edge of the deflector from the axis of rotation of the turbine (X), the vertical distance of the top edge of the deflector from the bottom of the blades (W), the length of the deflector (L), the width of the deflector (W), and the angle of the deflector with respect to the axis of rotation of the turbine (φ) were investigated. 16 three-dimensional numerical experiments were conducted to assess the effect of theses parameters on the power output of the wind turbine. Analyzing the results showed that the level of the influence of these five parameters can be ordered as φ>W>X>Y>L, which means that φ has the strongest impact on the performance of the wind turbine and L has the weakest impact. Utilizing the deflector with optimum parameters increased the efficiency of the wind turbine by 16.42% compare to the bare turbine.

Examination of Structural and Dynamic Properties for Vertical Axis Wind Turbine Blade Made of Stainless Steel using Ansys

This paper studies the potential for installing savonius type Vertical Axis Wind Turbine systems with the goal of maximizing the efficiency and reducing the cost. The wind turbine efficiency depends on the material of the blade, angle of the blade and shape of the blade. So material of the wind turbine blade plays an important role in the design of wind turbine. In this paper, Stainless Steel is used to design savonius wind blades of 1 m height and 0.5 m chord length with 4 different arc radii. For this purpose, CAD modeling software Solid Works is used to model savonius wind blade and static structural and modal analysis of the Stainless Steel blade is done by using ANSYS Workbench software. Static structural analysis is used to determine stress, strain, deformation and displacement under static loading condition. The response of structure for dynamic loading is determined by modal analysis. It is used to determine the natural frequency and mode shape of vibration of any structure. This wind turbine is suitable to install in small houses in urban areas.

Green touch for hydrogen production via alkaline electrolysis: The semi-flexible PV panels mounted wind turbine design, production and performance analysis

The novel solar-wind integrated system has been firstly used for hydrogen production in literature with validating theoretical, simulated and experimental studies. This integrated system consists of two main parts; solar-assisted wind turbine and alkaline electrolysis cell.In the first part of this system, the semi-flexible PV panels are smoothly integrated on the vertical axis wind turbine blade. This is a unique design in literature, unlike the hybrid systems that include wind turbines and solar PV panels in published literature. The production and testing of the hybrid integrated system in a single structure were performed both in laboratory conditions and also the system was set up the roof of ATU (Adana Alparslan Turkes Science and Technology University) in Adana. The second part includes hydrogen production via alkaline electrolysis system. The cathodes consist of nickel-coated copper (Cu/Ni) and nickel-vanadium binary coated copper (Cu/NiV), that was produced via electrodeposition technique by self-supporting. The performance of electrodes was compared in 1 M KOH solution via I–V behavior, electrochemical impedance spectroscopy, and long term cathodic polarization analysis. Results showed that polarization resistance was decreased almost 4 times by NiV when comparing the Ni. The surface inhomogeneity values were 0.91 and 0.81 for Cu/Ni and Cu/NiV respectively. The hydrogen gas evolved at the cathodes was also measured and higher volumes were detected for NiV binary coating.

Effects of blade shape and its corresponding moment of inertia on self-starting and power extraction performance of the novel bowl-shaped floating straight-bladed vertical axis wind turbine

In this paper, the effects of the blade shape and its corresponding moment of inertia on the performance of a novel bowl-shaped floating straight bladed vertical axis wind turbine (VAWT) have been investigated. A numerical method was developed and validated to accurately simulate the interaction between the wind and VAWT. Three inferential parameters, the starting time, mean power coefficient, and standard deviation of the aerodynamic force, were employed to evaluate the performance of the turbine with different blade shapes. Performance indicators including the self-starting capability, power extraction efficiency, and fatigue characteristics, were assessed. The results indicated that the VAWT with S-1046 blade had better overall performance as compared to the one with NACA0018 blade, where the reduced self-starting time, slight more or identical mean power coefficient, and minor standard deviation of Ft and Fn were observed. Further, the flow structure around the blade was also analyzed, it was found that at low wind speed (less than 6.0 m/s) separated vortex around the turbine is observed, whereas at high wind speed, attached vortex is observed. Fluctuation curves of power coefficient variation with tip speed ratio ‘λ’ were also noted for the wind induced rotation of VAWT. At low wind speed, the highest power coefficient amplitude was obtained when the turbine was at maximum tip speed ratio, whereas at high wind speed, the highest power coefficient amplitude was obtained when the tip speed ratio of the turbine was slight less than the maximum value. Based on these results, it is strongly recommended to apply thinner symmetry (S-1046) blade for designing VAWT.

Experimental and Numerical Investigations for Combined Blade Vertical Axis Wind Turbine

In this paper, experimental and numerical investigations were carried out to evaluate the drag force of a combined frame with movable vanes. For this purpose, the combined frame model was developed from a flat plate with three movable vanes and one Darrieus straight bladed NACA0012. A straight-bladed Darrieus NACA0012 airfoil is attached at the tip of the model structure. The design increases the starting and total torque of the model on the side, which rotates to wind direction, hence increasing the drag coefficient and reduces the negative torque on the other side of the frame that rotates opposite to the wind. Combined frame in experimental work is tested in the subsonic wind tunnel to analyze the performance parameters like drag force and drag coefficient . The frame is tested under different wind speed ranging from 4 m/s to 28 m/s, test results show the reliable and efficient performance. The results indicated that the maximum drag force for the combine frame is 6 N at experimental work and 5.649 at numerical simulation under the same condition (wind speed V=28 m/s and azimuth angle θ = 90°). Computational Fluid Dynamic software (CFD) ANSYS FLUENT is used in this simulation which is carried out for the combined frame to investigate the drag force and drag coefficient, The finite volume method with Shear Stress Transport (STT), k- turbulence model is used, the predicted results show that the flow through the combined frame at the negative side when all the vanes are freely open. The static pressure drops across the combined frame when the combined frame rotates to the negative side and the resistance of the combined frame to the flow decreased. This case helps to increase turbine angular velocity and this leads to an increase in the power coefficient of the turbine.

Blade thickness effect on the aerodynamic performance of an asymmetric NACA six series blade vertical axis wind turbine in low wind speed

ABSTRACTVertical axis wind turbine (VAWT) is an economic and widely used energy converter for converting wind energy into useful form of energy, like mechanical and electrical energy. For efficient energy conversion in low wind speed and to have improved power coefficient of asymmetric blade VAWT, selection of optimum blade thickness is needed thus entailing its detailed investigation with respect to different operating wind speed conditions. Present study methodically explores the impact of thickness to chord (t/c) ratio on aerodynamic performance of a three bladed asymmetrical blade H-Darrieus VAWT at different low wind speed conditions by using 2D unsteady CFD simulations. The optimal t/c is obtained on the basis of maximum power coefficient and average moment coefficient of the turbine. The aerodynamic performance curves are obtained at different operating and t/c conditions and the performance insights are corroborated with the findings from the flow physics study to come to some concrete conclusions on the effects of the thickness to chord ratio. The present study identifies large blade curvature to create a large diverging passage on the blade suction surface as the prominent reason for aerodynamic performance drop at a high t/c ratio.

Simulation studies to analyze the static mechanical properties of helical Savonius vertical axis wind turbine blade

The focus of this study is to analyze the static mechanical properties of the helical Savonius vertical axis wind turbine blade. Commercial finite element code ANSYS is used to perform the static structural analysis. The helical Savonius wind turbine blade is tested by force varying from 15 N to 25 N representing the wind conditions ranging from 5 m/s to 11 m/s. The properties namely, maximum principal stress, equivalent (von-misses) stress, shear stress, maximum shear stress, equivalent elastic strain, and total deformation are analysed. The various static mechanical properties are observed to be the maximum for wind load of 15 N. The outer edges of the helical Savonius vertical axis wind turbine blade is observed to have the maximum total deformation values and the prolonged use of the helical Savonius wind turbine blade will lead to damage along the outer edges of the turbine blade leading to failure of the wind turbine blade.

Evaluation of shape of Magatama type vertical axis wind turbine blade using Genetic Algorithm

Evaluation of shape of Magatama type vertical axis wind turbine blade using Genetic Algorithm

Aspects Regarding the Use of 3D Printing Technology and Composite Materials for Testing and Manufacturing Vertical Axis Wind Turbines

The article presents the technology and process, whereby a small-scale demonstration model and the real-scale prototype of vertical axis wind turbine blades are produced using rapid prototyping technology (3DP) and GFRP surface coatings, which help to improve the mechanical properties. In the end of the article the results of the production process and the advantages of combining these technologies are presented.

Turbulence and Energy Assessment of a Two Bladed H-Type Vertical Axis Wind Turbine Between Two High-Rise Buildings

Turbulence and Energy Assessment of a Two Bladed H-Type Vertical Axis Wind Turbine Between Two High-Rise Buildings

Investigation of V-shaped blade for the performance improvement of vertical axis wind turbines

The vertical axis wind turbine (VAWT) is regarded as an important device to utilize the renewable offshore wind energy to supplement the existing power systems. Hence, the demand for higher wind energy conversion makes the research focus on the blade optimization of wind turbines. This paper attempts to propose a novel VAWT structure with V-shaped blade to improve the power outputs at moderate tip speed ratios. The feasibility of the Reynolds-Averaged Navier-Stokes SST k-ω turbulence model applied on the VAWT was verified against available experiments at first. Then a comprehensive investigation on the aerodynamic performance of such V-shaped VAWT was carried out using the SST k-ω model. The results indicated that the maximum enhancement in power coefficient obtained in the optimal V-shaped blade was about 24.1%. In addition to the great improvement of the power efficiency, the V-shaped blade was proven to alleviate the damage caused by lateral loads to the wind turbine. Besides, the flow structures over the blade surface were studied to reveal the mechanism of dynamic stall with the reason of power increase explained. Moreover, it was found that the V-shaped blade could effectively suppress the flow separation and delay the dynamic stall in the middle of the blade, and the undesirable blade tip effect would not be more serious comparing to that of the conventional straight blade. It was finally concluded that the current work could be practically applied to the design and optimization of the VAWT blades.

Aerodynamic Performance of Trailing-Edge Modification of H-Type VAWT Blade Considering Camber Effect

This paper investigates the flow characteristics and wind energy utilizations of H-type vertical axis wind turbine (VAWT) blade and its trailing-edge modification while having a certain camber to facilitate a greater understanding of the effects of airfoil’s trailing-edge thickness and relative camber. The geometric dimensions are designed for 100 W wind wheel with NACA0021 airfoil, whose trailing-edge thickness is 0.442%c (with c the chord length), and the simulation accuracy of the Computational Fluid Dynamics (CFD) approach is validated through comparing the calculated results of the Realizable k–e turbulence model with experimental data. The blunt trailing-edge optimization of NACA0021 airfoil is performed by taking the maximum lift-drag ratio as the optimization objective, but the wind energy utilization of wind wheel with the optimized airfoil decreases with the increase of the trailing-edge thickness. Thus, the airfoil NACA0021 is modified to a sharp trailing-edge airfoil, namely, NACA0021S, and the wind energy utilization increases slightly. The airfoil’s relative camber is then increased by making the middle arc line locate on the circumference of wind wheel, and the effects of the relative camber on the pressure and vorticity distribution, torque, and wind energy utilization are analyzed. The results indicate that after the relative camber increases, the positive and negative pressure region areas decrease for NACA0021 and NACA0021S airfoils, and so do the length and distribution of the wake, but the torque coefficient and wind energy utilization increase.