scholarly journals Numerical Investigation of the Savonius Vertical Axis Wind Turbine and Evaluation of the Effect of the Overlap Parameter in Both Horizontal and Vertical Directions on Its Performance

Symmetry ◽  
2019 ◽  
Vol 11 (6) ◽  
pp. 821 ◽  
Author(s):  
Mohammad Ebrahimpour ◽  
Rouzbeh Shafaghat ◽  
Rezvan Alamian ◽  
Mostafa Safdari Shadloo
Keyword(s):  
Wind Turbine ◽  
Urban Areas ◽  
Weather Conditions ◽  
Vertical Axis ◽  
Power Coefficient ◽  
External Diameter ◽  
Vertical Axis Wind Turbine ◽  
Complex Process ◽  
Overlap Ratio ◽  
Volume Method

Exploiting wind energy, which is a complex process in urban areas, requires turbines suitable for unfavorable weather conditions, in order to trap the wind from different directions; Savonius turbines are suitable for these conditions. In this paper, the effect of overlap ratios and the position of blades on a vertical axis wind turbine is comprehensively investigated and analyzed. For this purpose, two positive and negative overlap situations are first defined along the X-axis and examined at the different tip speed ratios of the blade, while maintaining the size of the external diameter of the rotor, to find the optimum point; then, the same procedure is done along the Y-axis. The finite volume method is used to solve the computational fluid dynamics. Two-dimensional numerical simulations are performed using URANS equations and the sliding mesh method. The turbulence model employed is a realizable K-ε model. According to the values of the dynamic torque and power coefficient, while investigating horizontal and vertical overlaps along the X- and Y-axis, the blades with overlap ratios of HOLR = +0.15 and VOLR = +0.1 show better performances when compared to other corresponding overlaps. Accordingly, the average Cm and Cp improvements are 16% and 7.5%, respectively, compared to the base with a zero overlap ratio.

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°.

Development of the Dual Vertical Axis Wind Turbine Using Computational Fluid Dynamics

2017 ◽  
Vol 139 (12) ◽  
Author(s):  
Gabriel Naccache ◽  
Marius Paraschivoiu
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Wind Turbine ◽  
Urban Areas ◽  
High Efficiency ◽  
Three Dimensional ◽  
Vertical Axis ◽  
Power Coefficient ◽  
Circular Path ◽  
Vertical Axis Wind Turbine

Small vertical axis wind turbines (VAWTs) are good candidates to extract energy from wind in urban areas because they are easy to install, service, and do not generate much noise; however, the efficiency of small turbines is low. Here-in a new turbine, with high efficiency, is proposed. The novel design is based on the classical H-Darrieus VAWT. VAWTs produce the highest power when the blade chord is perpendicular to the incoming wind direction. The basic idea behind the proposed turbine is to extend that said region of maximum power by having the blades continue straight instead of following a circular path. This motion can be performed if the blades turn along two axes; hence, it was named dual vertical axis wind turbine (D-VAWT). The analysis of this new turbine is done through the use of computational fluid dynamics (CFD) with two-dimensional (2D) and three-dimensional (3D) simulations. While 2D is used to validate the methodology, 3D is used to get an accurate estimate of the turbine performance. The analysis of a single blade is performed and the turbine shows that a power coefficient of 0.4 can be achieved, reaching performance levels high enough to compete with the most efficient VAWTs. The D-VAWT is still far from full optimization, but the analysis presented here shows the hidden potential and serves as proof of concept.

scholarly journals Design of Rotor Blades for Vertical Axis Wind Turbine with Wind Flow Modifier for Low Wind Profile Areas

2020 ◽  
Vol 12 (19) ◽  
pp. 8050 ◽  
Author(s):  
Mohanasundaram Anthony ◽  
Valsalal Prasad ◽  
Kannadasan Raju ◽  
Mohammed H. Alsharif ◽  
Zong Woo Geem ◽  
...  
Keyword(s):  
Wind Turbine ◽  
Urban Areas ◽  
Wind Profile ◽  
Vertical Axis ◽  
Maximum Power ◽  
Power Coefficient ◽  
Wind Flow ◽  
Efficient Design ◽  
Vertical Axis Wind Turbine ◽  
Flow Modifier

This work focuses on the design and analysis of wind flow modifier (WFM) modeling of a vertical axis wind turbine (VAWT) for low wind profile urban areas. A simulation is carried out to examine the performance of an efficient low aspect ratio C-shaped rotor and a proposed involute-type rotor. Further, the WFM model is adapted with a stack of decreased diameter tubes from wind inlet to outlet. It accelerates the wind velocity, and its effectiveness is examined on the involute turbine. Numerical analysis is performed with a realizable K-ε model to monitor the rotor blade performance in the computational fluid dynamics (CFD) ANSYS Fluent software tool. This viscous model with an optimal three-blade rotor with 0.96 m2 rotor swept area is simulated between the turbine rotational speeds ranging from 50 to 250 rpm. The parameters, such as lift–drag coefficient, lift–drag forces, torque, power coefficient, and power at various turbine speeds, are observed. It results in a maximum power coefficient of 0.071 for the drag force rotor and 0.22 for the lift force involute rotor. Moreover, the proposed WFM with an involute rotor extensively improves the maximum power coefficient to an appreciable value of 0.397 at 5 m/s wind speed, and this facilitates efficient design in the low wind profile area.

scholarly journals NUMERICAL STUDY OF TWO VERTICAL AXIS WIND TURBINES DARRIEU TYPE LINED UP IN FUNCTION OF POWER COEFFICIENT1

2017 ◽  
Vol 6 (3) ◽  
Author(s):  
Rodrigo Spotorno Vieira ◽  
Luiz Alberto Oliveira Rocha ◽  
Liércio André Isoldi ◽  
Elizaldo Domingues Dos Santos
Keyword(s):  
Wind Turbine ◽  
Numerical Study ◽  
Mass Conservation ◽  
Vertical Axis ◽  
Power Coefficient ◽  
Vertical Axis Wind Turbine ◽  
Worst Case ◽  
Study Power ◽  
Great Possibility ◽  
Volume Method

In this work is performed a numerical study of the main operational principle of a VAWT (Vertical Axis Wind turbine) and the influence of the distance between two aligned turbines over their power coefficient. The main aims here are to evaluate the applicability of the numerical model studied here in further optimization studies of VAWT and evaluate the effect of the distance between turbines (d) on the device power coefficient. To achieve these goals, it is considered an incompressible, transient and turbulent flow on a two dimensional domain with two fluid zones, one being rotational representing the rotation of the blades. The time-averaged mass conservation equations and momentum are numerically solved using the finite volume method, more precisely with the software FLUENTÒ. For the approach of turbulence is used to classical modeling of turbulence (RANS) with standard model k - ε. Other geometric parameters: turbine radius (R), the airfoil profile (NACA0018) and chorus were held constant. The verification results showed a good agreement with those presented in the literature, even employing a simplified domain. It was also observed that the distance (d) directly affects the power of the second turbine. For the best case, with d =10m, the downstream turbine showed an approximate 50% drop in power coefficient in comparison with that obtained for the upstream turbine. While in the worst case, with d =2m, the power coefficient for the downstream turbine decreased two hundred times in comparison with that achieved for the upstream one. It was also noted that there is a great possibility of disposal area optimization of turbines in future studies. Keywords: Vertical Axis Wind turbine, Numerical study, Power coefficient, turbine distance.

Reduction in the torque ripple of a vertical axis wind turbine through foil pitching optimization

2019 ◽  
Vol 44 (2) ◽  
pp. 115-124 ◽  
Author(s):  
Gareth Erfort ◽  
Theodor W. von Backström ◽  
Gerhard Venter
Keyword(s):  
Wind Turbine ◽  
Urban Areas ◽  
Vertical Axis ◽  
Torque Ripple ◽  
Power Coefficient ◽  
Small Scale ◽  
Vertical Axis Wind Turbine ◽  
Similar Reduction ◽  
Vertical Axis Wind Turbines ◽  
Gradient Based

Vertical axis wind turbines have a place in the small scale renewable energy market. They are not currently implemented on a commercial scale but have found a niche space in urban areas. Here, the turbulent wind conditions and limited space are more easily tapped into with a vertical axis wind turbine. However, the challenges facing these types of turbines have hampered deployment. One of these issues is the fluctuating torque experienced during operation, which can lead to over-designed power trains. Genetic- and gradient-based optimization is applied to an analytical model of a vertical axis wind turbine, in order to reduce the torque fluctuation while attempting to maintain a high power coefficient. The reduction in torque ripple is achieved through a sinusoidal pitching motion of the blades. The torque ripple can be reduced by 10% with a similar reduction in power coefficient.

scholarly journals MODELING AND SIMULATION OF THE VERTICAL AXIS WIND TURBINE BY QBLADE SOFTWARE

2020 ◽  
Vol 2 (02) ◽  
pp. 181-188
Author(s):  
MERAD ◽  
Asmae BOUANANI ◽  
Mama BOUCHAOUR
Keyword(s):  
Wind Energy ◽  
Wind Turbine ◽  
Wind Turbines ◽  
Urban Areas ◽  
Clean Energy ◽  
Vertical Axis ◽  
Aerodynamic Characteristics ◽  
Simulation Software ◽  
Power Coefficient ◽  
Vertical Axis Wind Turbine

The use of wind energy has no harmful effects on the environment. This makes it a clean energy that is a real alternative to the problem of nuclear waste management and greenhouse gas emissions. Vertical axis wind turbines have prospective advantages in the field of domestic applications, because they have proven effectual in urban areas where wind flow conditions are intermittent, omnidirectional, unsteady and turbulent. The wind cannot ensure a regular energy supply without optimising the aerodynamics of the blades. This article presents a reminder about wind energy and wind turbines, especially the VAWT type wind turbines and also gives a presentation on the aerodynamic side of VAWT by studying the geometry and aerodynamic characteristics of the blade profiles with the acting forces and also the explanation of the DMS multiple flow tube model. This work also gives the different simulation methods to optimize the behaviour of the blades from the selected NACA profiles; the analysis first goes through the design of the blades by the design and simulation software Qblade which is used to calculate also the forces on the blade and the coefficients of lift, drag and fineness. At the end of this article we have the DMS simulation of the VAWT turbines, by determining the power coefficient and the power collected by the turbine to select the wind turbine adapted to a well characterized site.

scholarly journals Performance Enhancement of a Darrieus Vertical Axis Wind Turbine using Divergent Ducting System

2018 ◽  
Vol 25 (3) ◽  
pp. 58-66
Author(s):  
Abdullateef A. Jadallah ◽  
Sahar R. Farag ◽  
Jinan D. Hamdi
Keyword(s):  
Wind Turbine ◽  
Urban Areas ◽  
Performance Enhancement ◽  
Vertical Axis ◽  
Power Coefficient ◽  
Opening Angle ◽  
Vertical Axis Wind Turbine ◽  
Ansys Fluent ◽  
Low Wind Speed ◽  
Enhancement Method

Ducting system is an effective way to potentially augment the performance of wind turbine for applications in building architectures. This paper is aimed to study one of the possible enhancement method of the vertical axis wind turbine performance. It is characterized by adding divergent duct to facilitate imparting more flow rate. The divergent duct was designed and adapted with wind turbine. The system was modelled and simulated analytically and numerically. A computer program built in MATLAB 16 to simulate the performance of system. The performance and flow are also solved numerically using ANSYS-FLUENT 17.2. Two opening angles of the divergent -duct were employed to study the behavior of air flow through divergent duct and results were compared with base vertical axis wind turbine. The duct turbine with a straight wall type diffuser demonstrate power coefficient augmentation by 24.2% and 9.09% for opening angle 20 and 12 respectively. The optimum half opening angle was attained for the diffuser. The diffuser’s length of a half of the throat opening is recommended, and its angle of opening is 20. The diffuser was located in a stream-was direction that adequately aligned with the center of the vertical axis wind turbine. Results showed a reasonable influence on the performance of wind turbine. This technology may be used in gates and in urban areas with a relatively low wind speed regime.

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.

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.

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