Novel Vertical-Axis Wind Turbine With Articulated Blading

2012 ◽  
Author(s):  
H. Jericha ◽  
E. Göttlich ◽  
T. Selic ◽  
W. Sanz
Keyword(s):  
Wind Turbine ◽  
Wind Direction ◽  
Vertical Axis ◽  
Bevel Gear ◽  
Power Coefficient ◽  
Return Flow ◽  
Vertical Axis Wind Turbine ◽  
Guide Vanes ◽  
Wide Range ◽  
Gear Box

In this work a novel vertical-axis wind turbine is presented which can catch a wide range of wind velocities at high efficiencies. The wind turbine consists of a rotatable horizontal platform, where three symmetric blades are arranged which rotate with half of the platform angular speed but in opposite direction relative to it. The rotation of the blades allows them to adapt to the varying angle of attack of the wind during one revolution of the platform. The important characteristic is the design feature that the blades are inclined outwards to the vertical axis of the platform by an angle of about 20 deg. The inclination leads to an increased circumferential velocity along the blade span, so that the increasing wind velocity with height can be better captured. Also the chord length of the blades increases with the spanwise position. In order to better utilize the wind flow, guide vanes can be arranged which increase the flow to those blades currently moving with the wind and in return flow can even give proper windshield. The articulated blades are connected to the horizontal platform via a special planetary bevel gear box, so that the relative rotational movement of them is controlled by the rotating platform, in fact a rotating gear box. This unit itself is connected to a generator thus producing electrical energy. The wind turbine can be tracked to a changed wind direction by means of rotating the stationary center bevel-gear wheel, which at given wind direction is then kept at constant position. In this paper the design of wind turbine is described in detail and the advantages of the novel vertical-axis turbine are discussed. First CFD investigations of a 2D section without guide vanes are presented. They show that maximum power can be achieved for a wide range of speed ratios. The calculated power coefficient is about 0.36, an interesting value for vertical-axis wind turbines.

Aerodynamic and aeroacoustic performance investigations on modified H-rotor Darrieus wind turbine

2021 ◽  
pp. 0309524X2110039
Author(s):  
Amgad Dessoky ◽  
Thorsten Lutz ◽  
Ewald Krämer
Keyword(s):  
Wind Turbine ◽  
High Speed ◽  
Cfd Simulation ◽  
Vertical Axis ◽  
3D Models ◽  
Power Coefficient ◽  
Design Parameters ◽  
Second Phase ◽  
Vertical Axis Wind Turbine ◽  
Guide Vanes

The present paper investigates the aerodynamic and aeroacoustic characteristics of the H-rotor Darrieus vertical axis wind turbine (VAWT) combined with very promising energy conversion and steering technology; a fixed guide-vanes. The main scope of the current work is to enhance the aerodynamic performance and assess the noise production accomplished with such enhancement. The studies are carried out in two phases; the first phase is a parametric 2D CFD simulation employing the unsteady Reynolds-averaged Navier-Stokes (URANS) approach to optimize the design parameters of the guide-vanes. The second phase is a 3D CFD simulation of the full turbine using a higher-order numerical scheme and a hybrid RANS/LES (DDES) method. The guide-vanes show a superior power augmentation, about 42% increase in the power coefficient at λ = 2.75, with a slightly noisy operation and completely change the signal directivity. A remarkable difference in power coefficient is observed between 2D and 3D models at the high-speed ratios stems from the 3D effect. As a result, a 3D simulation of the capped Darrieus turbine is carried out, and then a noise assessment of such configuration is assessed. The results show a 20% increase in power coefficient by using the cap, without significant change in the noise signal.

Computational fluid dynamic analysis of roof-mounted vertical-axis wind turbine with diffuser shroud, flange, and vanes

2018 ◽  
Vol 42 (4) ◽  
pp. 404-415
Author(s):  
H. Abu-Thuraia ◽  
C. Aygun ◽  
M. Paraschivoiu ◽  
M.A. Allard
Keyword(s):  
Wind Turbine ◽  
Urban Areas ◽  
Guide Vane ◽  
Fluid Dynamic ◽  
Vertical Axis ◽  
Power Coefficient ◽  
Small Scale ◽  
Vertical Axis Wind Turbine ◽  
Guide Vanes ◽  
Turbine Design

Advances in wind power and tidal power have matured considerably to offer clean and sustainable energy alternatives. Nevertheless, distributed small-scale energy production from wind in urban areas has been disappointing because of very low efficiencies of the turbines. A novel wind turbine design — a seven-bladed Savonius vertical-axis wind turbine (VAWT) that is horizontally oriented inside a diffuser shroud and mounted on top of a building — has been shown to overcome the drawback of low efficiency. The objective this study was to analyze the performance of this novel wind turbine design for different wind directions and for different guide vanes placed at the entrance of the diffuser shroud. The flow field over the turbine and guide vanes was analyzed using computational fluid dynamics (CFD) on a 3D grid for multiple tip-speed ratios (TSRs). Four wind directions and three guide-vane angles were analyzed. The wind-direction analysis indicates that the power coefficient decreases to about half when the wind is oriented at 45° to the main axis of the turbine. The analysis of the guide vanes indicates a maximum power coefficient of 0.33 at a vane angle of 55°.

scholarly journals Performance Analysis of Highway Wind Turbine Enhanced with Wind Guide Vanes Using the Taguchi Method

CFD letters ◽  
2021 ◽  
Vol 13 (3) ◽  
pp. 25-42
Author(s):  
Mohamad Zahid Mazlan ◽  
Fazila Mohd Zawawi ◽  
Teeab Tahzib ◽  
Kamarulafizam Ismail ◽  
Syahrullail Samion
Keyword(s):  
Taguchi Method ◽  
Wind Turbine ◽  
Wind Velocity ◽  
Guide Vane ◽  
Vertical Axis ◽  
Power Coefficient ◽  
Vertical Axis Wind Turbine ◽  
Guide Vanes ◽  
Moving Vehicle ◽  
Low Wind Speed

Considerable efforts have been made by researchers to study the interaction between moving vehicles and wind turbines. The Savonius vertical-axis wind turbine was chosen due to its effectiveness in low-wind speed conditions. Speeding vehicles produce a scattered and non-uniform wind flow with disturbances. Hence, to prevent a negative torque, a row of wind guide vane panels was arranged in front of the blades of a wind turbine. The wind guide vane had the shape of an NACA4412 aerofoil to reduce the loss of wind energy, and to further increase wind velocity. A number of CFD simulations were designed using the Taguchi method to determine the optimum conditions for the power coefficient of the wind turbine in terms of the effects of three factors, namely, the distance between the guide vanes (d), the angle of the guide vanes (?), and the speed of the moving car (VC). An orthogonal array of L9(33) was designed. In addition, to observe the effects of the wind velocity induced by the moving vehicle, the wind turbine was incorporated with one degree of freedom (1DOF). The results showed that the speed of the moving car played a major role in determining the power coefficient. The order of influence of each factor was ranked as VC > ? > d. The performance of the wind turbine was sensitive to the speed of the car and the angle of the guide vanes, whereas it was insensitive to the distance between the guide vanes. Furthermore, the analysis of the signal-to-noise (S/N) ratio suggested that the optimal combination of factors for a maximum power coefficient were d = 0.4m, ? = 30°, and VC =30m/s. The optimum setting increased the Cp to 26% compared to the Cp that was produced without the installation of the guide vanes.

scholarly journals Performance Analysis of a H-Darrieus Wind Turbine for a Series of 4-Digit NACA Airfoils

Energies ◽  
2020 ◽  
Vol 13 (12) ◽  
pp. 3196 ◽  
Author(s):  
Krzysztof Rogowski ◽  
Martin Otto Laver Hansen ◽  
Galih Bangga
Keyword(s):  
Wind Turbine ◽  
Vertical Axis ◽  
Point Of View ◽  
Power Coefficient ◽  
Navier Stokes ◽  
Vertical Axis Wind Turbine ◽  
Wide Range ◽  
Sst Turbulence Model ◽  
Lift And Drag ◽  
Blade Loads

The purpose of this paper is to estimate the H-Darrieus wind turbine aerodynamic performance, aerodynamic blade loads, and velocity profiles downstream behind the rotor. The wind turbine model is based on the rotor designed by McDonnell Aircraft Company. The model proposed here consists of three fixed straight blades; in the future, this model is planned to be developed with controlled blades. The study was conducted using the unsteady Reynolds averaged Navier–Stokes (URANS) approach with the k-ω shear stress transport (SST) turbulence model. The numerical two-dimensional model was verified using two other independent aerodynamic approaches: a vortex model and the extended version of the computational fluid dynamics (CFD) code FLOWer. All utilized numerical codes gave similar result of the instantaneous aerodynamic blade loads. In addition, steady-state calculations for the applied airfoils were also made using the same numerical model as for the vertical axis wind turbine (VAWT) to obtain lift and drag coefficients. The obtained values of lift and drag force coefficients, for a Reynolds number of 2.9 million, agree with the predictions of the experiment and XFOIL over a wide range of angle of attack. A maximum rotor power coefficient of 0.5 is obtained, which makes this impeller attractive from the point of view of further research. Research has shown that, if this rotor were to work with fixed blades, it is recommended to use the NACA 1418 airfoil instead of the original NACA 0018.

Numerical Study of Pitch Angle on H-Type Vertical Axis Wind Turbine

2012 ◽  
Vol 499 ◽  
pp. 259-264
Author(s):  
Qi Yao ◽  
Ying Xue Yao ◽  
Liang Zhou ◽  
S.Y. Zheng
Keyword(s):  
Wind Turbine ◽  
Pitch Angle ◽  
Numerical Study ◽  
Vertical Axis ◽  
Azimuth Angle ◽  
Power Coefficient ◽  
Cfd Model ◽  
Vertical Axis Wind Turbine ◽  
Sliding Mesh ◽  
Mesh Technique

This paper presents a simulation study of an H-type vertical axis wind turbine. Two dimensional CFD model using sliding mesh technique was generated to help understand aerodynamics performance of this wind turbine. The effect of the pith angle on H-type vertical axis wind turbine was studied based on the computational model. As a result, this wind turbine could get the maximum power coefficient when pitch angle adjusted to a suited angle, furthermore, the effects of pitch angle and azimuth angle on single blade were investigated. The results will provide theoretical supports on study of variable pitch of wind turbine.

Numerical Research on the Characteristics of Lift-Drag Type Vertical Axis Wind Turbine

2012 ◽  
Vol 189 ◽  
pp. 448-452
Author(s):  
Yan Jun Chen ◽  
Guo Qing Wu ◽  
Yang Cao ◽  
Dian Gui Huang ◽  
Qin Wang ◽  
...  
Keyword(s):  
Wind Turbine ◽  
Vertical Axis ◽  
Chord Length ◽  
Power Coefficient ◽  
Speed Ratio ◽  
Vertical Axis Wind Turbine ◽  
Tip Speed Ratio ◽  
Middle Range ◽  
Parabolic Form ◽  
Cfd Method

Numerical studies are conducted to research the performance of a kind of lift-drag type vertical axis wind turbine (VAWT) affected by solidity with the CFD method. Moving mesh technique is used to construct the model. The Spalart-Allmaras one equation turbulent model and the implicit coupled algorithm based on pressure are selected to solve the transient equations. In this research, how the tip speed ratio and the solidity of blade affect the power coefficient (Cp) of the small H-VAWT is analyzed. The results indicate that Cp curves exhibit approximate parabolic form with its maximum in the middle range of tip speed ratio. The two-blade wind turbine has the lowest Cp while the three-blade one is more powerful and the four-blade one brings the highest power. With the certain number of blades, there is a best chord length, and too long or too short chord length may reduce the Cp.

Experimental Study of Vertical Axis Wind Turbine with Wind Speed Self-Adapting

2012 ◽  
Vol 215-216 ◽  
pp. 1323-1326
Author(s):  
Ming Wei Xu ◽  
Jian Jun Qu ◽  
Han Zhang
Keyword(s):  
Wind Speed ◽  
Wind Turbine ◽  
Wind Velocity ◽  
Vertical Axis ◽  
Maximum Power ◽  
The Self ◽  
Power Coefficient ◽  
Speed Ratio ◽  
Vertical Axis Wind Turbine ◽  
Opening And Closing

A small vertical axis wind turbine with wind speed self-adapting was designed. The diameter and height of the turbine were both 0.7m. It featured that the blades were composed of movable and fixed blades, and the opening and closing of the movable blades realized the wind speed self-adapting. Aerodynamic performance of this new kind turbine was tested in a simple wind tunnel. Then the self-starting and power coefficient of the turbine were studied. The turbine with load could reliably self-start and operate stably even when the wind velocity was only 3.6 m/s. When the wind velocity was 8 m/s and the load torque was 0.1Nm, the movable blades no longer opened and the wind turbine realized the conversion from drag mode to lift mode. With the increase of wind speed, the maximum power coefficient of the turbine also improves gradually. Under 8 m/s wind speed, the maximum power coefficient of the turbine reaches to 12.26%. The experimental results showed that the new turbine not only improved the self-starting ability of the lift-style turbine, but also had a higher power coefficient in low tip speed ratio.

scholarly journals Double multiple stream tube theory coupled with dynamic stall and wake correction for aerodynamic investigation of vertical axis wind turbine

2020 ◽  
Vol 23 (4) ◽  
pp. 771-780
Author(s):  
Anh Ngoc VU ◽  
Ngoc Son Pham
Keyword(s):  
Wind Turbine ◽  
Shape Function ◽  
Vertical Axis ◽  
Transformation Method ◽  
Aerodynamic Performance ◽  
Dynamic Stall ◽  
Power Coefficient ◽  
Vertical Axis Wind Turbine ◽  
Stream Tube ◽  
Aerodynamic Investigation

This study describes an effectively analytic methodology to investigate the aerodynamic performance of H vertical axis wind turbine (H-VAWT). An in-house code based on double multiple stream tube theory (DMST) coupled with dynamic stall and wake correction is implemented to estimate the power coefficient. Design optimization of airfoil shape is conducted to study the influences of the dynamic stall and turbulent wakes. Airfoil shape is universally investigated by using the Class/Shape function transformation method. The airfoil study shows that the upper curve tends to be less convex than the lower curve in order to extract more energy of the wind upstream and generate less drag of the blade downstream. The optimal results show that the power coefficient increases by 6.5% with the new airfoil shape.

Optimized Small Vertical Axis Wind Turbine (VAWT), Phase I

2021 ◽  
Author(s):  
Moshe Zilberman ◽  
Abdelaziz Abu Sbaih ◽  
Ibrahim Hadad
Keyword(s):  
Wind Energy ◽  
Wind Turbine ◽  
Wind Turbines ◽  
Cost Effective ◽  
Clean Energy ◽  
Vertical Axis ◽  
Low Noise ◽  
Power Coefficient ◽  
Vertical Axis Wind Turbine ◽  
Different Types

Abstract Wind energy has become an important resource for the growing demand for clean energy. In 2020 wind energy provided more than 6% of the global electricity demand. It is expected to reach 7% at the end of 2021. The installation growth rate of small wind turbines, though, is relatively slow. The reasons we are interested in the small vertical axis wind turbines are their low noise, environmentally friendly, low installation cost, and capable of being rooftop-mounted. The main goal of the present study is an optimization process towards achieving the optimal cost-effective vertical wind turbine. Thirty wind turbine models were tested under the same conditions in an Azrieli 30 × 30 × 90 cm low-speed wind tunnel at 107,000 Reynolds number. The different types of models were obtained by parametric variations of five basic models, maintaining the same aspect ratio but varying the number of bucket phases, the orientation angles, and the gaps between the vanes. The best performing turbine model was made of one phase with two vanes of non-symmetric bipolynomial profiles that exhibited 0.2 power coefficient, relative to 0.16 and 0.13 that were obtained for symmetrical polynomial and the original Savonius type turbines, respectively. Free rotation, static forces and moments, and dynamic moments and power were measured for the sake of comparison and explanation for the variations in performances of different types of turbines. CFD calculations were used to understand the forces and moment behaviors of the optimized turbine.

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