The Straight-Bladed Morphing Vertical Axis Wind Turbine

Pitch Control ◽

Control Schemes ◽

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.

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

Wind Engineering ◽

10.1177/0309524x211061828 ◽

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 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.

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

10.1115/gtindia2021-74879 ◽

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 ◽

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.

An experimental study of the optimal design parameters of a wind power tower used to improve the performance of vertical axis wind turbines

Advances in Mechanical Engineering ◽

10.1177/1687814018799543 ◽

2018 ◽

Vol 10 (9) ◽

pp. 168781401879954

Author(s):

Soo-Yong Cho ◽

Sang-Kyu Choi ◽

Jin-Gyun Kim ◽

Chong-Hyun Cho

Keyword(s):

Experimental Study ◽

Optimal Design ◽

Wind Turbine ◽

Wind Power ◽

Wind Turbines ◽

Vertical Axis ◽

Power Coefficient ◽

Design Parameters ◽

Vertical Axis Wind Turbines

In order to augment the performance of vertical axis wind turbines, wind power towers have been used because they increase the frontal area. Typically, the wind power tower is installed as a circular column around a vertical axis wind turbine because the vertical axis wind turbine should be operated in an omnidirectional wind. As a result, the performance of the vertical axis wind turbine depends on the design parameters of the wind power tower. An experimental study was conducted in a wind tunnel to investigate the optimal design parameters of the wind power tower. Three different sizes of guide walls were applied to test with various wind power tower design parameters. The tested vertical axis wind turbine consisted of three blades of the NACA0018 profile and its solidity was 0.5. In order to simulate the operation in omnidirectional winds, the wind power tower was fabricated to be rotated. The performance of the vertical axis wind turbine was severely varied depending on the azimuthal location of the wind power tower. Comparison of the performance of the vertical axis wind turbine was performed based on the power coefficient obtained by averaging for the one periodic azimuth angle. The optimal design parameters were estimated using the results obtained under equal experimental conditions. When the non-dimensional inner gap was 0.3, the performance of the vertical axis wind turbine was better than any other gaps.

CFD Investigation of the Multiple Rotors Darrieus Type Turbine Performance

Volume 9: Oil and Gas Applications; Supercritical CO2 Power Cycles; Wind Energy ◽

10.1115/gt2019-91491 ◽

2019 ◽

Cited By ~ 1

Author(s):

Omar Sherif Mohamed ◽

Ahmed Ibrahim ◽

Ahmed M. R. El Baz

Keyword(s):

Urban Areas ◽

Low Cost ◽

Vertical Axis ◽

Power Coefficient ◽

Cfd Simulations ◽

Close Proximity ◽

Computational Fluid Dynamics Cfd ◽

Overall Performance

Abstract The last few years have witnessed researches concerned by vertical axis wind turbine (VAWT) performance considering its advantages compared to the horizontal axis wind turbines, as it can be operated in urban areas without producing noise, ease of maintenance and simple construction, in addition to its low cost. More interest is growing in developing efficient clusters of VAWT in order to increase power generation at specific sites by using multiple turbines. In the present work, the performance of various configurations of Darrieus type VAWT clusters is examined using computational fluid dynamics (CFD) simulations. The objective of this work is to increase the overall power coefficient of the turbines cluster compared to single rotor performance. This objective shall be achieved by examining mutual interactions between rotors arranged in close proximity and examining the effect of oblique angle between rotors on overall performance of the cluster of rotors. The performance is assessed by observing the overall power coefficient of the cluster. Also, the velocity wake of the simulated three rotors turbine cases was analyzed and compared to the that of the single rotor.

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

Volume 8: Supercritical CO2 Power Cycles; Wind Energy; Honors and Awards ◽

10.1115/gt2013-94979 ◽

2013 ◽

Cited By ~ 5

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 ◽

First Case ◽

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.

Wind Tunnel Experiment on the Aerodynamic Interaction Between Vertical Axis Wind Turbine Pair

10.1115/fedsm2021-65280 ◽

2021 ◽

Author(s):

Hao Su ◽

Haoran Meng ◽

Jia Guo ◽

Timing Qu ◽

Liping Lei

Keyword(s):

Wind Tunnel ◽

Wind Turbine ◽

Wind Turbines ◽

Vertical Axis ◽

Power Coefficient ◽

Power Performance ◽

Array Configuration ◽

Aerodynamic Interaction ◽

Positive Effect

Abstract Wind energy has attracted worldwide attention as a pollution-free and widely distributed renewable energy source. Increasing the power density by optimizing the arrangement of wind turbines has been a popular field of research in recent years. In the present work, a systematic study on the influence of array configuration on vertical axis wind turbines is made through wind tunnel experiments. Firstly, the power performance of an isolated vertical axis wind turbine at different tip speed ratios is tested as a benchmark of comparison. Multiple situations of two-turbine configurations are then tested and the results are compared with the isolated wind turbine. The power coefficient of the turbine pair increases by 34% when the turbines are 2.4 rotor diameters apart and rotate in the same direction. In the counter-rotating co-leeward case, it is demonstrated that the turbine pairs will have a positive effect on each other when they are separated by 2.1 rotor diameters to 2.4 rotor diameters. The lateral spacing between the counter-rotating co-windward turbine pair should be greater than 1.5 rotor diameters to avoid turbulence interference between the rotors.

Power Enhancement of a Vertical Axis Wind Turbine Equipped with an Improved Duct

Energies ◽

10.3390/en14185780 ◽

2021 ◽

Vol 14 (18) ◽

pp. 5780

Author(s):

Mohammad Hassan Ranjbar ◽

Behnam Rafiei ◽

Seyyed Abolfazl Nasrazadani ◽

Kobra Gharali ◽

Madjid Soltani ◽

...

Keyword(s):

Wind Turbine ◽

Wind Turbines ◽

Flow Characteristics ◽

Maximum Velocity ◽

Leading Edge ◽

Vertical Axis ◽

Power Coefficient ◽

Numerical Solver ◽

Main Components

Efforts to increase the power output of wind turbines include Diffuser Augmented Wind Turbines (DAWT) or a shroud for the rotor of a wind turbine. The selected duct has three main components: a nozzle, a diffuser, and a flange. The combined effect of these components results in enriched upstream velocity for the rotor installed in the throat of the duct. To obtain the maximum velocity in the throat of the duct, the optimum angles of the three parts have been analyzed. A code was developed to allow all the numerical steps including changing the geometries, generating the meshes, and setting up the numerical solver simultaneously. Finally, the optimum geometry of the duct has been established that allows a doubling of the flow velocity. The flow characteristics inside the duct have also been analyzed in detail. An H-Darrieus Vertical Axis Wind Turbine (VAWT) has been simulated inside the optimized duct. The results show that the power coefficient of the DAWT can be enhanced up to 2.9 times. Deep dynamic stall phenomena are captured perfectly. The duct advances the leading-edge vortex generation and delays the vortex separation.

Recent Development in the Design of Wind Deflectors for Vertical Axis Wind Turbine: A Review

Energies ◽

10.3390/en14165140 ◽

2021 ◽

Vol 14 (16) ◽

pp. 5140

Author(s):

Altaf Hussain Rajpar ◽

Imran Ali ◽

Ahmad E. Eladwi ◽

Mohamed Bashir Ali Bashir

Keyword(s):

Wind Turbines ◽

Vertical Axis ◽

Optimization Techniques ◽

Rotor Blades ◽

Power Coefficient ◽

Potential Contribution ◽

Vertical Axis Wind Turbines ◽

Network Costs

Developments in the design of wind turbines with augmentation are advancing around the globe with the goal of generating electricity close to the user in built-up areas. This is certain to help lessen the power generation load as well as distribution and transmission network costs by reducing the distance between the user and the power source. The main objectives driving the development and advancement of vertical-axis wind turbines are increasing the power coefficient and the torque coefficient by optimizing the upstream wind striking on the rotor blades. Unlike horizontal-axis wind turbines, vertical axis turbines generate not only positive torque but also negative torque during operation. The negative torque generated by the returning blade is a key issue for vertical-axis wind turbines (VAWTs) that is counterproductive. Installation of wind deflectors for flow augmentation helps to reduce the negative torque generated by the returning blades as well as enhance the positive torque by creating a diversion in the upstream wind towards the forwarding blade during operation. This paper reviews various designs, experiments, and CFD simulations of wind deflectors reported to date. Optimization techniques for VAWTs incorporating wind deflectors are discussed in detail. The main focus of the review was on the installation position and orientation of the deflectors and their potential contribution to increasing the power coefficient. Topics for future study are suggested in the conclusion section of the paper.

Blades Optimization for Maximum Power Output of Vertical Axis Wind Turbine

International Journal of Renewable Energy Development ◽

10.14710/ijred.2021.35530 ◽

2021 ◽

Vol 10 (3) ◽

pp. 585-595

Author(s):

Ahmad Adnan Shoukat ◽

Adnan Aslam Noon ◽

Muhammad Anwar ◽

Hafiz Waqar Ahmed ◽

Talha Irfan Khan ◽

...

Keyword(s):

Wind Turbine ◽

Wind Turbines ◽

Vertical Axis ◽

Edge Length ◽

Research Network ◽

Power Coefficient ◽

Low Wind Speed ◽

Edge Profile ◽

Power Yield

Wind power is a significant and urging sustainable power source asset to petroleum derivatives. Wind machines, for example, H-Darrieus vertical pivot wind turbines (VAWTs) have increased much notoriety in research network throughout the most recent couple of decades because of their applications at destinations having moderately low wind speed. Be that as it may, it is noticed that such wind turbines have low effectiveness. The point of this examination is to plan rotor cutting edges which could create most extreme power yield and execution. Different plan factors, for instance, harmony length, pitch edge, rotor distance across, cutting edge length and pitch point are explored to upgrade the presentation of VAWT. Rotor cutting edges are manufactured using the NACA-0030 structure and tried in wind burrow office and contrast its outcomes and DSM 523 profile. Numerical simulations are performed to get best geometry and stream conduct for achieving greatest power. It is seen that for higher tip-speed-proportion (TSR), shorter harmony length and bigger distance across the rotor (i.e., lower robustness) yields higher effectiveness in NACA 0030. Nevertheless, for lower TSR, the more drawn out agreement length and slighter distance across rotor (i.e., higher strength) gives better implementation. The pitch point is - 2° for TSR = 3 and - 3° for TSR = 2.5. The most extreme power yield of the wind turbine is acquired for the sharp edge profile NACA 0030. Besides, instantaneous control coefficient, power coefficient (CP) is the greatest reason for azimuthal edge of 245° and least esteem for 180°.

Generator-Damped Torsional Vibrations of a Vertical Axis Wind Turbine

Wind Engineering ◽

10.1260/030952405775992625 ◽

2005 ◽

Vol 29 (5) ◽

pp. 449-461 ◽

Cited By ~ 14

Author(s):

Sandra Eriksson ◽

H. Bernhoff

Keyword(s):

Wind Turbine ◽

Wind Turbines ◽

Synchronous Generator ◽

Vertical Axis ◽

Critical Issue ◽

Torsional Vibrations ◽

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.