Design and Analysis of the Aerodynamic Components for a Kilowatt Scale VAWT Optimized for Low Altitude Implementation in Remote Rural Villages

2011 ◽  
Author(s):  
Nathan E. Fuller ◽  
David M. Wiens ◽  
Allison L. Johnston ◽  
Jesse J. French
Keyword(s):  
Wind Turbine ◽  
Transmission Lines ◽  
Low Income ◽  
Vertical Axis ◽  
Operating Conditions ◽  
Maximum Efficiency ◽  
Vertical Axis Wind Turbine ◽  
Rural Villages ◽  
Aerodynamic Properties ◽  
Horizontal Axis Wind Turbines

The ideal operating conditions for traditional horizontal axis wind turbines (HAWTs) are generally described by high velocity, steady winds, and undisturbed, laminar air flow. In the direct vicinity of populated areas, these conditions can only be achieved at altitudes significantly above or beyond the built-up area, typically twice the height of the tallest surrounding obstruction. The cost of tower material and transmission lines makes placing turbines at optimal operating heights cost-prohibitive in low-income, remote villages. Though not ideal for HAWT operation, the wind close to the earth’s surface and in proximity of residences can be utilized with an appropriately designed vertical axis wind turbine (VAWT). These turbines, while having a lower theoretical maximum efficiency, can survive and utilize the turbulent multidirectional winds in this operating region while still providing usable power. This paper highlights the design and analysis work performed by the authors to increase the aerodynamic efficiency of a unique and patented VAWT design in order to optimize it for implementation in remote rural villages. The final product is a kW capacity VAWT of unique geometry based on the previous successful testing of a 100W prototype. Specifically, the authors explored the aerodynamic effects of varying the geometry of the radial arms and center hubs of the turbine using CFD and wind tunnel testing. The design goal was to develop arms with aerodynamic properties that complemented the function of the blades at the appropriate phases of a single revolution. While the previous prototype focused mainly on minimizing drag, this effort sought to design an arm profile that develops high drag in one airflow direction and minimizes drag in the opposite direction. Implementation of these results was realized in a fully functioning drag VAWT. Furthermore, the system was designed to keep the turbine affordable for remote populations with limited resources. This data is compared to theoretical performance calculations, existing wind turbine designs, and against predictions made using scaling factors on preexisting data from the smaller prototype.

Vertical axis wind turbine operation in icing conditions: A review study

2021 ◽  
pp. 0309524X2110618
Author(s):  
Syed Abdur Rahman Tahir ◽  
Muhammad Shakeel Virk
Keyword(s):  
Wind Turbine ◽  
Wind Turbines ◽  
Vertical Axis ◽  
Electricity Production ◽  
Vertical Axis Wind Turbine ◽  
Vertical Axis Wind Turbines ◽  
Horizontal Axis Wind Turbines ◽  
Promising Solution ◽  
Review Study ◽  
Accretion Physics

Vertical Axis Wind Turbine (VAWT) can be a promising solution for electricity production in remote ice prone territories of high north, where good wind resources are available, but icing is a challenge that can affect its optimum operation. A lot of research has been made to study the icing effects on the conventional horizontal axis wind turbines, but the literature about vertical axis wind turbines operating in icing conditions is still scarce, despite the importance of this topic. This paper presents a review study about existing knowledge of VAWT operation in icing condition. Focus has been made in better understanding of ice accretion physics along VAWT blades and methods to detect and mitigate icing effects.

Development and Application of a Simulation Tool for Vertical and Horizontal Axis Wind Turbines

2013 ◽  
Author(s):  
David Marten ◽  
Juliane Wendler ◽  
Georgios Pechlivanoglou ◽  
Christian Navid Nayeri ◽  
Christian Oliver Paschereit
Keyword(s):  
Wind Turbine ◽  
Wind Turbines ◽  
Vertical Axis ◽  
Turbine Rotor ◽  
Horizontal Axis ◽  
Vertical Axis Wind Turbine ◽  
First Case ◽  
Horizontal Axis Wind Turbines ◽  
Lift And Drag ◽  
The Impact

A double-multiple-streamtube vertical axis wind turbine simulation and design module has been integrated within the open-source wind turbine simulator QBlade. QBlade also contains the XFOIL airfoil analysis functionalities, which makes the software a single tool that comprises all functionality needed for the design and simulation of vertical or horizontal axis wind turbines. The functionality includes two dimensional airfoil design and analysis, lift and drag polar extrapolation, rotor blade design and wind turbine performance simulation. The QBlade software also inherits a generator module, pitch and rotational speed controllers, geometry export functionality and the simulation of rotor characteristics maps. Besides that, QBlade serves as a tool to compare different blade designs and their performance and to thoroughly investigate the distribution of all relevant variables along the rotor in an included post processor. The benefits of this code will be illustrated with two different case studies. The first case deals with the effect of stall delaying vortex generators on a vertical axis wind turbine rotor. The second case outlines the impact of helical blades and blade number on the time varying loads of a vertical axis wind turbine.

The Straight-Bladed Morphing Vertical Axis Wind Turbine

2016 ◽  
Author(s):  
David MacPhee ◽  
Asfaw Beyene
Keyword(s):  
Wind Turbine ◽  
Wind Turbines ◽  
Low Cost ◽  
Vertical Axis ◽  
Power Coefficient ◽  
Vertical Axis Wind Turbine ◽  
Pitch Control ◽  
Control Schemes ◽  
Horizontal Axis Wind Turbines ◽  
Novel Concept

Blade pitch control has been extremely important for the development of Horizontal-Axis Wind Turbines (HAWTs), allowing for greater efficiency over a wider range of operational regimes when compared to rigid-bladed designs. For Vertical-Axis Wind Turbines (VAWTs), blade pitching is inherently more difficult due to a dependence of attack angle on turbine armature location, shaft speed, and wind speed. As a result, there have been very few practical pitch control schemes put forward for VAWTs, which may be a major reason why this wind turbine type enjoys a much lower market share as compared to HAWTs. To alleviate this issue, the flexible, straight-bladed vertical-axis turbine is presented, which can passively adapt its geometry to local aerodynamic loadings and serves as a low-cost blade pitch control strategy increasing efficiency and startup capabilities. Using two-dimensional fluid-structure action simulations, this novel concept is compared to an identical rigid one and is proven to be superior in terms of power coefficient due to decreased torque minima. Moreover, due to the flexible nature of the blades, the morphing turbine achieves less severe oscillatory loadings. As a result, the morphing blade design is expected to not only increase efficiency but also system longevity without additional system costs usually associated with active pitch control schemes.

scholarly journals Effects of turbulence models and grid densities on computational accuracy of flows over a vertical axis wind turbine

2018 ◽  
Vol 7 (3) ◽  
pp. 213-222
Author(s):  
Jaruwan Chaiyanupong ◽  
Tawit Chitsomboon
Keyword(s):  
Shear Stress ◽  
Wind Turbine ◽  
Turbulence Model ◽  
Turbulence Models ◽  
Vertical Axis ◽  
Operating Conditions ◽  
Speed Ratio ◽  
Vertical Axis Wind Turbine ◽  
Computational Accuracy ◽  
Shear Stress Transport

Flows through a vertical axis wind turbine (VAWT) are very complex due to their inherent unsteadiness caused by large variations of the angle of attacks as the turbine is rotating and changing its azimuth angles simultaneously. In addition, a turbine must go through a wide range of operating conditions especially the change in blade speed ratio (BSR). Accurate prediction of flows over VAWT using Reynolds-Averaged Navier-Stokes (RANS) model needs a well-tested turbulence model as well as a careful grid control around the airfoil. This paper aimed to compare various turbulence models and seek the most accurate one. Furthermore, grid convergence was studied using the Roache method to determine the sufficient number of grid elements around the blade section. The three-dimensional grid was generated by extrution from the two-dimensional grid along with the appropriate y+ controlling. Comparisons were made among the three turbulence models that are widely used namely: the RNG model, the shear stress transport k-ω model (SST) and the Menter’s shear stress transport k-ω model (transition SST). Results obtained clearly showed that turbulence models significantly affected computational accuracy. The SST turbulence model showed best agreement with reported experimental data at BSR lower than 2.35, while the transition SST model showed better results when BSR is higher than 2.35. In addition, grid extruding technique with y+ control could reduce total grid requirement while maintaining acceptable prediction accuracy.Article History: Received April 15th 2018; Received in revised form June 16th 2018; Accepted September 17th 2018; Available onlineHow to Cite This Article: Chaiyanupong,J and Chitsomboon, T. (2018) Effects of Turbulence Models and Grid Densities on Computational Accuracy of Flows Over a Vertical Axis Wind Turbine. Int. Journal of Renewable Energy Development, 7(3), 213-222.http://dx.doi.org/10.14710/ijred.7.3.213-222

CFD and Control Analysis of a Smart Hybrid Vertical Axis Wind Turbine

2018 ◽  
Author(s):  
Arian Hosseini ◽  
Navid Goudarzi
Keyword(s):  
Wind Turbine ◽  
Vertical Axis ◽  
Power Coefficient ◽  
Control Analysis ◽  
Vertical Axis Wind Turbine ◽  
Aerodynamic Properties ◽  
Switch Mechanism ◽  
Electro Magnetic ◽  
Operational Range ◽  
And Control

Wind energy has become a dominant source of renewable energy during the past decade. Current hybrid wind turbines are primarily designed and manufactured based on a combination of aerodynamic properties for both Darrieus and Savonius turbines. In this work, the aerodynamic performance characteristics of a smart vertical axis wind turbine (VAWT) with an electro-magnetic switch mechanism for dis-/engagement mechanism is studied analytically and numerically. The proposed novel VAWT offers a high start-up torque by a Savonius turbine and high power coefficient values by a Darrieus turbine. The switch mechanism can further improve the system efficiency by running the turbines together or independently. The proposed hybrid VAWT was modeled as a combined Savonius-type Bach turbine and a 3-bladed H-Darrieus turbine. The hybrid turbine has a self-startup feature and reaches a coefficient of power (Cp) of over 40%. The turbine is also estimated to cover a wide operational range up to TSR 6. The follow on research phases of the project include studying the proposed smart VAWT experimentally and validating the results with those obtained through computational analysis.

scholarly journals Numerical evaluation of aerodynamic performances of vertical-axis wind turbine rotor with flow concentrator

2020 ◽  
Author(s):  
Jelena Svorcan ◽  
◽  
Ognjen Peković ◽  
Toni Ivanov ◽  
Miloš Vorkapić ◽  
...  
Keyword(s):  
Wind Turbine ◽  
Three Dimensional ◽  
Vertical Axis ◽  
Turbine Rotor ◽  
Operating Conditions ◽  
Power Coefficient ◽  
Small Scale ◽  
Vertical Axis Wind Turbine ◽  
Flow Simulations ◽  
Wind Speeds

With wind energy extraction constantly increasing, the interest in small-scale urban wind turbines is also expanding. Given that these machines often work in adverse operating conditions (Earth’s boundary layer, vortex trails of surrounding objects, small and changeable wind speeds), additional elements that locally augment wind velocity and facilitate turbine start may be installed. This paper investigates possible benefits of adding an optimized flow concentrator to a vertical-axis wind turbine (VAWT) rotor. Three-dimensional, unsteady, turbulent, incompressible flow simulations of both isolated rotor consisting of three straight blades and a rotor with flow concentrator have been performed in ANSYS FLUENT by finite volume method for several different operational regimes. This type of flow simulations is challenging since flow angles are high, numerous flow phenomena and instabilities are present and the interaction between the blades and detached vortices can be significant. The rotational motion of the blades is solved by the unsteady Sliding Mesh (SM) approach. Flow field is modeled by Unsteady Reynolds Averaged Navier-Stokes (URANS) equations with k-ω SST turbulence model used for closure. Both quantitative and qualitative examinations of the obtained numerical results are presented. In particular, the two computed power coefficient curves are compared and the advantages of installing a flow concentrator are accentuated.

Generator-Damped Torsional Vibrations of a Vertical Axis Wind Turbine

2005 ◽  
Vol 29 (5) ◽  
pp. 449-461 ◽  
Author(s):  
Sandra Eriksson ◽  
H. Bernhoff
Keyword(s):  
Wind Turbine ◽  
Wind Turbines ◽  
Synchronous Generator ◽  
Vertical Axis ◽  
Critical Issue ◽  
Torsional Vibrations ◽  
Vertical Axis Wind Turbine ◽  
Fundamental Vibration ◽  
Drive Trains ◽  
Horizontal Axis Wind Turbines

Torsional vibrations may be a critical issue for those vertical axis wind turbines having long drive trains as compared with standard horizontal axis wind turbines. Such vibrations are studied by simulation for two different types of generators used with a vertical axis wind turbine, namely a conventional induction generator with a gearbox and a directly-driven multipole synchronous generator. The synchronous generator has been designed with FEM simulations. The didactic calculations show from first principles that a directly-driven generator is to be preferred when torsional vibrations are considered, since the eigenfrequency of the fundamental vibration is greater for a directly driven generator than otherwise. Thus, the risk of resonance is reduced in a stiff assembly. The generator damping of the vibrations for the simulated, directly-driven synchronous generator is also studied.

scholarly journals Predicted and measured performance of a vertical axis wind turbine with passive variable pitch compared to fixed pitch

2016 ◽  
Vol 41 (1) ◽  
pp. 74-90 ◽  
Author(s):  
Brian K Kirke ◽  
Benoit Paillard
Keyword(s):  
Wind Turbine ◽  
Control Mechanism ◽  
Vertical Axis ◽  
Dynamics Simulation ◽  
Maximum Efficiency ◽  
Vertical Axis Wind Turbine ◽  
Actual Performance ◽  
Variable Pitch ◽  
Starting Torque ◽  
Fixed Pitch

The performance of a 5-m diameter Darrieus vertical axis wind turbine was predicted using both a double multiple streamtube model and a two-dimensional unsteady Reynolds-averaged Navier–Stokes computational fluid dynamics simulation with constant rotational speed for a series of operational points. The actual performance was measured in both fixed and variable pitch modes. The aims were (1) to compare starting torque and peak efficiency in fixed and variable pitch modes and (2) to test an overspeed control mechanism. Starting torque was approximately three times higher in variable pitch mode and the maximum efficiency on some runs was significantly higher. The overspeed control mechanism functioned consistently as designed. Thus, variable pitch was shown to overcome two major disadvantages of normal fixed pitch vertical axis wind turbines, self-starting and overspeed control. Discrepancies between the predicted and measured results showed the importance of accurately assessing parasitic drag losses and the need for three-dimensional simulation to give reliable performance predictions.

scholarly journals Health Monitoring and Diagnosis System for a Small H-Type Darrieus Vertical-Axis Wind Turbine

Energies ◽  
2021 ◽  
Vol 14 (21) ◽  
pp. 7246
Author(s):  
Sungmok Hwang ◽  
Cheol Yoo
Keyword(s):  
Wind Turbine ◽  
Real Time ◽  
Wind Turbines ◽  
Health Monitoring ◽  
Vertical Axis ◽  
Power Production ◽  
Operating Conditions ◽  
Vertical Axis Wind Turbine ◽  
Diagnosis System ◽  
Monitoring And Diagnosis

As the wind power market grows rapidly, the importance of technology for real-time monitoring and diagnosis of wind turbines is increasing. However, most of the developed technologies and research mainly focus on large horizontal-axis wind turbines, and research conducted on small- and medium-sized wind turbines is rare. In this study, a novel low-cost and real-time health monitoring and diagnosis system for the small H-type Darrieus vertical axis wind turbine is proposed. Turbine operating conditions were classified into parked/idle and power production. In the case of the power production condition, abnormality diagnosis was performed using key monitoring parameters, including vibration, fundamental frequency, the bending stress of the tower and generator vibration. The turbine abnormalities were diagnosed in two stages by applying the alert and alarm limits, determined by referring to international standards and material properties and the long-term measurement data together.

scholarly journals Flow Characteristics of a Straight-Bladed Vertical Axis Wind Turbine with Inclined Pitch Axes

Energies ◽  
2020 ◽  
Vol 13 (23) ◽  
pp. 6281
Author(s):  
Jia Guo ◽  
Liping Lei
Keyword(s):  
Wind Turbine ◽  
Wind Turbines ◽  
Wind Farm ◽  
Flow Characteristics ◽  
Wind Farms ◽  
Vertical Axis ◽  
Incline Angle ◽  
Vertical Axis Wind Turbine ◽  
Unsteady Wake ◽  
Horizontal Axis Wind Turbines

Currently, vertical axis wind turbines (VAWT) are considered as an alternative technology to horizontal axis wind turbines in specific wind conditions, such as offshore farms. However, complex unsteady wake structures of VAWTs exert a significant influence on performance of wind turbines and wind farms. In the present study, instantaneous flow fields around and downstream of an innovative VAWT with inclined pitch axes are simulated by an actuator line model. Unsteady flow characteristics around the wind turbine with variations of azimuthal angles are discussed. Several fluid parameters are then evaluated on horizontal and vertical planes under conditions of various fold angles and incline angles. Results show that the total estimated wind energy in the shadow of the wind turbine with an incline angle of 30° and 150° is 4.6% higher than that with an incline angle of 90°. In this way, appropriate arrangements of wind turbines with various incline angles have the potential to obtain more power output in a wind farm.

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