scholarly journals Design and Simulation of a 1 DOF Planetary Speed Increaser for Counter-Rotating Wind Turbines with Counter-Rotating Electric Generators

Energies ◽  
2019 ◽  
Vol 12 (9) ◽  
pp. 1754 ◽  
Author(s):  
Mircea Neagoe ◽  
Radu Saulescu ◽  
Codruta Jaliu
Keyword(s):  
Wind Turbines ◽  
Large Scale ◽  
Computing Methodology ◽  
Patent Application ◽  
Analytical Models ◽  
Small Scale ◽  
Efficient Operation ◽  
Electric Generator ◽  
Planetary Gearbox ◽  
Electric Generators

The improvement of wind turbine performance poses a constant challenge to researchers and designers in the field. As a result, the literature presents new concepts of wind turbines (WTs), such as: counter-rotating wind turbines (CRWTs) with two coaxial wind rotors revolving in opposite directions, WTs with higher-efficiency and downsized transmission systems, or WTs with counter-rotating electric generators (CREGs). Currently, there are a few solutions of WTs, both containing counter-rotating components; however, they can only be used in small-scale applications. Aiming to extend the use of WTs with counter-rotating wind rotors (CRWRs) and CREGs to medium- and large-scale applications, this paper introduces and analyzes a higher-performance WT solution, which integrates two counter-rotating wind rotors, a 1 degree of freedom (DOF) planetary speed increaser with four inputs and outputs, and a counter-rotating electric generator. The proposed system yields various technical benefits: it has a compact design, increases the output power (which makes it suitable for medium- and large-scale wind turbines) and allows a more efficient operation of the electric generator. The kinematic and static computing methodology, as well as the analytical models and diagrams developed for various case studies, might prove useful for researchers and designers in the field to establish the most advantageous solution of planetary speed increasers for the CRWTs with CREGs. Moreover, this paper extends the current database of WT speed increasers with an innovative concept of 1 DOF planetary gearbox, which is subject to a patent application.

Detailed Analysis of the Wake Structure of a Straight-Blade H-Darrieus Wind Turbine by Means of Wind Tunnel Experiments and Computational Fluid Dynamics Simulations

2017 ◽  
Vol 140 (3) ◽  
Author(s):  
Alessandro Bianchini ◽  
Francesco Balduzzi ◽  
Giovanni Ferrara ◽  
Lorenzo Ferrari ◽  
Giacomo Persico ◽  
...  
Keyword(s):  
Fluid Dynamics ◽  
Experimental Data ◽  
Computational Fluid Dynamics ◽  
Wind Tunnel ◽  
Wind Turbines ◽  
Large Scale ◽  
Vertical Axis ◽  
Performance Estimation ◽  
Small Scale ◽  
Dynamics Simulations

Darrieus vertical axis wind turbines (VAWTs) have been recently identified as the most promising solution for new types of applications, such as small-scale installations in complex terrains or offshore large floating platforms. To improve their efficiencies further and make them competitive with those of conventional horizontal axis wind turbines, a more in depth understanding of the physical phenomena that govern the aerodynamics past a rotating Darrieus turbine is needed. Within this context, computational fluid dynamics (CFD) can play a fundamental role, since it represents the only model able to provide a detailed and comprehensive representation of the flow. Due to the complexity of similar simulations, however, the possibility of having reliable and detailed experimental data to be used as validation test cases is pivotal to tune the numerical tools. In this study, a two-dimensional (2D) unsteady Reynolds-averaged Navier–Stokes (U-RANS) computational model was applied to analyze the wake characteristics on the midplane of a small-size H-shaped Darrieus VAWT. The turbine was tested in a large-scale, open-jet wind tunnel, including both performance and wake measurements. Thanks to the availability of such a unique set of experimental data, systematic comparisons between simulations and experiments were carried out for analyzing the structure of the wake and correlating the main macrostructures of the flow to the local aerodynamic features of the airfoils in cycloidal motion. In general, good agreement on the turbine performance estimation was constantly appreciated.

An Analysis and Experimental Study of the Rotor Blade with Composite Material Fiber Reinforced Plastics

2006 ◽  
Vol 306-308 ◽  
pp. 851-856
Author(s):  
C.Y. Son ◽  
H.I. Byun ◽  
K.H. Kim ◽  
J.K. Choi ◽  
J.Y. Shin
Keyword(s):  
Wind Turbines ◽  
Rotor Blade ◽  
Large Scale ◽  
Fem Analysis ◽  
Small Scale ◽  
Fiber Reinforced ◽  
Fatigue Load ◽  
Reinforced Plastics ◽  
Bending Load ◽  
Behavior Characteristic

In these days, large-scale wind turbines are being made of the Glass Fiber Reinforced Plastic (hereinafter F.R.P). Some reinforcement stiffeners such as carbon fiber and polyamide (Kevlar) are not economical for the wind turbine. In addition, the steel or aluminum alloy, featuring heavy weight and metallic fatigue load, is not suitable for global use, except very small-scale wind turbines. In this study, we manufactured a 10kW-grade small Rotor Blade with the F. R. P featuring high stiffness and good dynamic behavior characteristic, and carried out experiments for understanding the bending behavior characteristic of the fatigue load and bending load. And, we examined the experiment results through the Finite Element Method. We compared the experiment results and FEM analysis outputs using the commercial ANSYS FEM program.

scholarly journals Unsteady aerodynamic analysis for offshore floating wind turbines under different wind conditions

2015 ◽  
Vol 373 (2035) ◽  
pp. 20140080 ◽  
Author(s):  
B. F. Xu ◽  
T. G. Wang ◽  
Y. Yuan ◽  
J. F. Cao
Keyword(s):  
Experimental Data ◽  
Wind Turbine ◽  
Wind Turbines ◽  
Large Scale ◽  
Aerodynamic Performance ◽  
Small Scale ◽  
Floating Platform ◽  
Unsteady Aerodynamic ◽  
Blade Root ◽  
Platform Motions

A free-vortex wake (FVW) model is developed in this paper to analyse the unsteady aerodynamic performance of offshore floating wind turbines. A time-marching algorithm of third-order accuracy is applied in the FVW model. Owing to the complex floating platform motions, the blade inflow conditions and the positions of initial points of vortex filaments, which are different from the fixed wind turbine, are modified in the implemented model. A three-dimensional rotational effect model and a dynamic stall model are coupled into the FVW model to improve the aerodynamic performance prediction in the unsteady conditions. The effects of floating platform motions in the simulation model are validated by comparison between calculation and experiment for a small-scale rigid test wind turbine coupled with a floating tension leg platform (TLP). The dynamic inflow effect carried by the FVW method itself is confirmed and the results agree well with the experimental data of a pitching transient on another test turbine. Also, the flapping moment at the blade root in yaw on the same test turbine is calculated and compares well with the experimental data. Then, the aerodynamic performance is simulated in a yawed condition of steady wind and in an unyawed condition of turbulent wind, respectively, for a large-scale wind turbine coupled with the floating TLP motions, demonstrating obvious differences in rotor performance and blade loading from the fixed wind turbine. The non-dimensional magnitudes of loading changes due to the floating platform motions decrease from the blade root to the blade tip.

Detailed Analysis of the Wake Structure of a Straight-Blade H-Darrieus Wind Turbine by Means of Wind Tunnel Experiments and CFD Simulations

2017 ◽  
Author(s):  
Alessandro Bianchini ◽  
Francesco Balduzzi ◽  
Giovanni Ferrara ◽  
Lorenzo Ferrari ◽  
Giacomo Persico ◽  
...  
Keyword(s):  
Experimental Data ◽  
Wind Tunnel ◽  
Wind Turbines ◽  
Large Scale ◽  
Vertical Axis ◽  
Performance Estimation ◽  
Small Scale ◽  
Horizontal Axis Wind Turbines ◽  
Floating Platforms ◽  
Physical Phenomena

Darrieus Vertical Axis Wind Turbines (VAWTs) have been recently identified as the most promising solution for new types of applications, such as small-scale installations in complex terrains or offshore large floating platforms. To improve their efficiencies further and make them competitive with those of conventional horizontal axis wind turbines, a more in depth understanding of the physical phenomena that govern the aerodynamics past a rotating Darrieus turbine is needed. Within this context, Computational Fluid Dynamics (CFD) can play a fundamental role, since it represents the only model able to provide a detailed and comprehensive representation of the flow. Due to the complexity of similar simulations, however, the possibility of having reliable and detailed experimental data to be used as validation test cases is pivotal to tune the numerical tools. In this study, a two-dimensional U-RANS computational model was applied to analyze the wake characteristics on the mid plane of a small-size H-shaped Darrieus VAWT. The turbine was tested in a large-scale, open-jet wind tunnel, including both performance and wake measurements. Thanks to the availability of such a unique set of experimental data, systematic comparisons between simulations and experiments were carried out analyzing the structure of the wake, and correlating the main macro-structures of the flow to the local aerodynamic features of the airfoils in cycloidal motion. In general, good agreement on the turbine performance estimation was constantly appreciated.

Experimental Methodologies for the Measurement of Wind Turbines Performance

2010 ◽  
Author(s):  
Carlo Romano` ◽  
Vincenzo Orlando ◽  
Giuliana Mattiazzo ◽  
Ermanno Giorcelli
Keyword(s):  
Wind Turbines ◽  
Renewable Energy Sources ◽  
Operative Procedure ◽  
Angular Speed ◽  
Small Scale ◽  
Electric Generator ◽  
Research Activities ◽  
Wide Range ◽  
Load Cells ◽  
Physical Quantities

Wind Turbines are one of the most promising technologies to exploit renewable energy sources, and maybe the one which is the closest to achieve grid parity. Many modeling and experimental research activities are carried out in order to continuously improve devices performance. Another promising sector is small scale turbines, below 100kW installed power, for small installation, domestic use, and to be installed on ships. Moving within this scenario, a 1,5 kW turbine was tested inside a wind tunnel, and the following were measured: forces applied to the tower, angular speed, electric power output, mechanical power involved, and stress induced on the blades. Moreover, the cut in rotor speed and the turbine’s efficiency came as outputs of the activity. After some simple forecast calculations, to establish expected maximum values of physical quantities, the experiment was designed. The method used for acquiring all the values at one time involves a wi-fi device, attached to the rotor, in order to acquire signals coming from strain-gauges placed on the blades, avoiding long and cumbersome transmission lines towards the DAQ, coupled to anemometers, load cells, and a wattmeter. Coordination of operators during the tests had a crucial role in carrying out the procedure correctly. Since the main objects of study were blades, rotor and electric generator, the tower has been replaced with a robust support structure, designed to host and protect load cells and signal conditioners from accidental damage, thus permitting a correct measurement of axial force applied to the rotor and reacting momentum of the generator. The wi-fi device was linked to the rotor, in order to affect its mass and inertia characteristics as less as possible. This required the design of a proper linking structure, which was light and well balanced despite being mechanically resistant. Measured quantities are useful to evaluate the turbine’s performance (efficiency, power curve, cut in speed), and also to validate some fem and multi physics predictive models, that are currently under development, as possible tools for general wind turbines design. The outputs of these tests satisfy the need for a wide range of experimental data. This way of designing tests, the physical quantities involved and the schedule of experiments can be suggested as a valuable operative procedure.

Development of a High Efficiency and Long Life 500W Class H-Darrieus Type VAWT (Vertical Axis Wind Turbine) System Using Skin-Spar-Foam Sandwich Composite Structure

2012 ◽  
Author(s):  
Changduk Kong ◽  
Haseung Lee
Keyword(s):  
Wind Turbine ◽  
Wind Turbines ◽  
Large Scale ◽  
Performance Test ◽  
High Efficiency ◽  
Vertical Axis ◽  
Small Scale ◽  
Vertical Axis Wind Turbine ◽  
Horizontal Axis Wind Turbine ◽  
Structural Test

Since the energy crisis and the environmental issue have been focused due to excessive fossil fuel consumption, the wind power has been considered as an important renewable energy source. Recently, several MW class large scale wind turbine systems have been developed in some countries. Even though the large scale wind turbine can effectively produce the electrical power, the small scale wind turbines have been continuously developed due some advantages, for instance, it can be easily built by low cost without any limitation of location, i.e. even in city. In case of small scale wind turbines, the vertical axis wind turbine (VAWT) is used in city having frequent wind direction change, even though it has a bit lower efficient than the horizontal axis wind turbine. Furthermore, most small scale wind turbine systems have been designed at the rated wind speed of around 12m/s. This work is to design a high efficiency 500W class composite VAWT blade which is applicable to relatively low speed region. In the aerodynamic design of blade, the parametric studies are carried out to decide an optimal aerodynamic configuration. The aerodynamic efficiency and performance of the designed VAWT is confirmed by the CFD analysis. The structural design is performed by the load case study, the initial sizing using the netting rule and the rule of mixture, the structural analysis using FEM, the fatigue life estimation and the structural test. The prototype blade is manufactured by the hand lay-up and the matched die molding. The experimental structural test results are compared with the FEM analysis results. Finally, to evaluate the prototype VAWT including designed blades, the performance test is performed using a truck to simulate the various range wind speeds and some measuring equipments. According to the performance evaluation result, the estimated performance is well agreed with the experimental test result in all operating ranges.

scholarly journals A supervised machine-learning method for optimizing the automatic transmission system of wind turbines

2022 ◽  
Vol 10 (1) ◽  
pp. 35-56 ◽  
Author(s):  
Habeeb A. H. R. Aladwani ◽  
Mohd Khairol Anuar Ariffin ◽  
Faizal Mustapha
Keyword(s):  
Machine Learning ◽  
Wind Speed ◽  
Wind Turbines ◽  
Large Scale ◽  
Learning Algorithm ◽  
Automatic Transmission ◽  
Transmission System ◽  
Supervised Machine Learning ◽  
Small Scale ◽  
Low Efficiency

Large-scale wind turbines mostly use Continuously Variable Transmission (CVT) as the transmission system, which is highly efficient. However, it comes with high complexity and cost too. In contrast, the small-scale wind turbines that are available in the market offer a one-speed gearing system only where no gear ratios are varied, resulting in low efficiency of harvesting energy and leading to gears failure. In this research, an unsupervised machine-learning algorithm is proposed to address the energy efficiency of the automatic transmission system in vertical axis wind turbines (VAWT), to increase its efficiency in harvesting energy. The aim is to find the best adjustment for VAWT while the automatic transmission system is taken into account. For this purpose, the system is simulated and tested under various gear ratios conditions while a centrifugal clutch is applied to automatic gear shifting. The outcomes indicated that the automatic transmission system could successfully adjust the spinning in line with the wind speed. As a result, the obtained level of harvested voltage and power by VAWT with the automatic transmission system are improved significantly. Consequently, it is concluded that automatic VAWTs, equipped with the machine-learning capability can readjust themselves with the wind speed more efficiently.

scholarly journals Dimensional Analysis in Power Predicting of a Real Scale Wind Turbine Based on Wind Tunnel Torque Measurement of Small Scaled Models

2018 ◽  
Author(s):  
Sutrisno Sutrisno ◽  
Sigit Iswahyudi ◽  
Setyawan Wibowo
Keyword(s):  
Wind Tunnel ◽  
Wind Turbine ◽  
Wind Turbines ◽  
Large Scale ◽  
Correlation Equation ◽  
Field Size ◽  
Speed Ratio ◽  
Small Scale ◽  
Torque Measurement ◽  
Turbine Design

A preliminary study of a wind turbine design is carried out using a wind tunnel to obtain its aerodynamic characteristics. Utilization of data from the study to develop large-scale wind turbines requires further study. This paper aims to discuss the use of wind turbine data obtained from the wind tunnel measurements to estimate the characteristics of wind turbines that have field size. The torque of two small-scale turbines was measured inside the wind tunnel. The first small-scale turbine has a radius of 0.14 m and the second small turbine has a radius of 0.19 m. Torque measurement results from both turbines were analyzed using Buckingham π theorem to obtain a correlation between torsion and diameter variations. The obtained correlation equation is used to estimate the field measurement of turbine power with a radius of 1.2 m. The resulting correlation equation can be used to estimate the power generated by the turbine by the size of the field well in the operating area of the tip speed ratio of the turbine design.

scholarly journals Barotropic Instability of a Cyclone Core at Kilometer‐Scale Resolution

2020 ◽  
Author(s):  
David Leutwyler ◽  
Christoph Schär
Keyword(s):  
Large Scale ◽  
Low Pressure ◽  
Analytical Models ◽  
Real Case ◽  
Horizontal Wind ◽  
Small Scale ◽  
Barotropic Instability ◽  
Instability Mechanism ◽  
Frontal Systems ◽  
Case Simulation

<p>Secondary disturbances spawning frontal waves along the fronts of mature midlatitude low-pressure systems were identified decades ago from satellite images. While their development has been studied using analytical models, field campaigns (e.g. FASTEX) and re-analysis datasets, simulation of the phenomenon in state-of-the-art global weather and climate models so far remained unattainable.</p><p>Today's flagship supercomputers allow performing simulations at kilometer-scale resolution on computational domains covering the entire lifecycle of synoptic-scale systems and thus enable explicit representation of small-scale disturbances embedded in large-scale circulations. We demonstrate these capabilities in two different types of kilometer-scale simulations. The first is a 10-day-long near-global simulation of an idealized moist baroclinic wave, performed at 1 km grid spacing and employing 16,001 × 36,006 × 60 grid points. The second is a real-case simulation of an extratropical low-pressure system, driven by the European Centre for Medium-Range Weather Forecasts's operational analysis. At kilometer-scale resolution, both simulations display clear evidence of embedded mesoscale vortices spawning along frontal systems of mature extratropical cyclones. The vortices appearing in the real-case simulation can also be identified in satellite imagery of the system.</p><p> The simulated developments are due to a barotropic instability mechanism and driven by strong low-level horizontal wind shear. While the simulation of the frontal systems is amenable at model resolutions around 10–50 km, the instability mechanism itself relies on the representation of a narrow shear zone, requiring about 5 times finer resolution. Results suggest that the flow regimes suppressing or fostering barotropic vortices can coexist in the same synoptic system. Far away from the cyclone core, the instability is suppressed by deformation associated with the large-scale flow, while close to the mature cyclone core, the narrow frontal structure becomes unstable.</p><p><strong>Leutwyler, D. </strong>and C. Schär (2019): Barotropic instability of a cyclone core at kilometer-scale resolution, J. Adv. Model. Earth Sy., 11. <span></span></p>

An Examination of the Effect of Reynolds Number on Airfoil Performance

2011 ◽  
Author(s):  
Tim Burdett ◽  
Jason Gregg ◽  
Kenneth Van Treuren
Keyword(s):  
Experimental Data ◽  
Reynolds Number ◽  
Wind Turbines ◽  
Large Scale ◽  
Reynolds Numbers ◽  
Energy Sources ◽  
Small Scale ◽  
Number Range ◽  
Low Reynolds Numbers ◽  
Low Reynolds

The standard of living throughout the world has increased dramatically over the last 30 years and is projected to continue to rise. This growth leads to an increased demand on conventional energy sources, such as fossil fuels. However, these are finite resources. Thus, there is an increasing demand for alternative energy sources, such as wind energy. Much of current wind turbine research focuses on large-scale (>1 MW), technologically-complex wind turbines installed in areas of high average wind speed (>20 mph). An alternative approach is to focus on small-scale (1–10kW), technologically-simple wind turbines built to produce power in low wind regions. While these turbines may not be as efficient as the large-scale systems, they require less industrial support and a less complicated electrical grid since the power can be generated at the consumer’s location. To pursue this approach, a design methodology for small-scale wind turbines must be developed and validated. This paper addresses one element of this methodology, airfoil performance prediction. In the traditional design process, an airfoil is selected and published lift and drag curves are used to optimize the blade twist and predict performance. These published curves are typically generated using either experimental testing or a numeric code, such as PROFIL (the Eppler Airfoil Design and Analysis Code) or XFOIL. However, the published curves often represent performance over a different range of Reynolds numbers than the actual design conditions. Wind turbines are typically designed from 2-D airfoil data, so having accurate airfoil data for the design conditions is critical. This is particularly crucial for small-scale, fixed-pitched wind turbines, which typically operate at low Reynolds numbers (<500,000) where airfoil performance can change significantly with Reynolds number. From a simple 2-D approach, the ideal operating condition for an airfoil to produce torque is the angle of attack at which lift is maximized and drag is minimized, so prediction of this angle will be compared using experimental and simulated data. Theoretical simulations in XFOIL of the E387 airfoil, designed for low Reynolds numbers, suggest that this optimum angle for design is Reynolds number dependent, predicting a difference of 2.25° over a Reynolds number range of 460,000 to 60,000. Published experimental data for the E387 airfoil demonstrate a difference of 2.0° over this same Reynolds number range. Data taken in the Baylor University Subsonic Wind Tunnel for the S823 airfoil shows a similar trend. This paper examines data for the E387 and S823 airfoils at low Reynolds numbers (75,000, 150,000, and 200,000 for the S823) and compares the experimental data with XFOIL predictions and published PROFIL predictions.

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