Evaluation Criteria and Estimate of Output From a Small-Scale Wind Turbine

2011 ◽  
Author(s):  
Dorothy S. Small
Keyword(s):  
Wind Turbine ◽  
Wind Turbines ◽  
Wind Profile ◽  
Historical Data ◽  
Three Dimensional ◽  
Evaluation Criteria ◽  
Specific Site ◽  
Small Scale ◽  
Site Conditions

This paper will evaluate a specific site located in southwestern Virginia, providing design criteria that are important considerations at this site. The evaluation will predict the output from a 6 blade HAWT model at the height and location of the site. As a small scale wind turbine, the process of determination of relevant considerations to establish the turbine selection and output are weighted to establish the evaluation criteria. A review of the specific site conditions are presented in detail. This information includes: three-dimensional topographic review, wind and weather profile of the site and surrounding environmental conditions of the site. With this information the decision path for the specific siting is discussed. Characteristics of the site that will be considered to calculate output are: historical data of wind profile of the region, height of tower, affect of other objects and affect of wind turbulence. A discussion of current modeling options will be compared. The design and components of the small scale wind turbine chosen for this application will be compared to other wind turbines of similar size and cost. Considerations of the turbine that are considered are: size of wind turbine, cost of wind turbine, predictable output of the wind turbine based on design of the various wind turbines, requirements for the tower for each turbine and predicted maintenance for each turbine. Initial performance of the selected turbine will be available by presentation of information.

Wind Profile Effect on Small Wind Turbine Noise Generation

2014 ◽  
Author(s):  
Aki Grönman ◽  
Jari Backman ◽  
Anna Avramenko
Keyword(s):  
Wind Turbine ◽  
Wind Profile ◽  
Three Dimensional ◽  
Ground Surface ◽  
Aerodynamic Noise ◽  
Speed Ratio ◽  
Small Scale ◽  
Noise Generation ◽  
Acoustic Analogy ◽  
Wind Profiles

Small wind turbines are usually located close to buildings, and therefore, the noise generation can be both annoying and a risk for the health. The number of wind turbine installations is growing, and the request for distributed small scale energy production is one of the future trends in the energy market. The wind behavior is usually non-linear close to the ground surface. Especially, small turbines with low nacelle heights have a relatively declined wind profile at the blades. The chosen modeling approach coupled three-dimensional RANS with the Ffowcs Williams-Hawkings acoustic analogy. A series of numerical simulations was performed to study the reliability of the modeling. Three different grids were used to study the grid independency close to the turbine nominal tip to speed ratio. A reasonable agreement in the noise trends was found between the modeling and the measurements and previous studies. This encouraged us to study three different wind profiles with a down scaled wind turbine model. The results indicate that the aerodynamic noise of small turbines is not markedly affected by the wind profile.

Statistical Analysis of Component Failures: A 16 Year Survey on More Than 550 Wind Turbines

2018 ◽  
Vol 140 (12) ◽  
Author(s):  
Lorenzo Ferrari ◽  
Guido Soldi ◽  
Alessandro Bianchini ◽  
Enzo Dalpane
Keyword(s):  
Statistical Analysis ◽  
Wind Turbine ◽  
Wind Turbines ◽  
Good Prediction ◽  
Component Failure ◽  
Machine Age ◽  
Detailed Survey ◽  
Maintenance Program ◽  
Component Failures

A good prediction of the failure ratio of wind turbine (WT) components is pivotal to define a correct maintenance program and reduce the downtime periods. Even a small failure can lead to long downtime periods and high repairing costs. The installation sites, which generally have limited accessibility, and the necessity of special facilities to reach the components inside the nacelle, also play a key role in the correct management of WTs. In this study, a detailed survey on the failures occurred to the WTs managed by the Italian operator “e2i energie speciali” (more than 550 machines) over 16 years was performed and the results were analyzed in detail. Each failure was classified by considering the damaged component and the related downtime period. The analysis allowed the determination of several useful results such as the trend of failure occurrence with machine age and the identification of components and macrocomponents which are more critical in terms of both number of occurrences and downtime periods. The combination of component failure occurrences and related downtime periods was also computed to estimate which component is most critical for WT operation.

scholarly journals Investigation of an Innovative Rotor Modification for a Small-Scale Horizontal Axis Wind Turbine

Energies ◽  
2020 ◽  
Vol 13 (10) ◽  
pp. 2649 ◽  
Author(s):  
Artur Bugała ◽  
Olga Roszyk
Keyword(s):  
Wind Speed ◽  
Wind Turbine ◽  
Cfd Simulation ◽  
Turbine Blades ◽  
Three Dimensional ◽  
Horizontal Axis ◽  
Power Coefficient ◽  
Small Scale ◽  
Horizontal Axis Wind Turbine ◽  
Airflow Distribution

This paper presents the results of the computational fluid dynamics (CFD) simulation of the airflow for a 300 W horizontal axis wind turbine, using additional structural elements which modify the original shape of the rotor in the form of multi-shaped bowls which change the airflow distribution. A three-dimensional CAD model of the tested wind turbine was presented, with three variants subjected to simulation: a basic wind turbine without the element that modifies the airflow distribution, a turbine with a plano-convex bowl, and a turbine with a centrally convex bowl, with the hyperbolic disappearance of convexity as the radius of the rotor increases. The momentary value of wind speed, recorded at measuring points located in the plane of wind turbine blades, demonstrated an increase when compared to the base model by 35% for the wind turbine with the plano-convex bowl, for the wind speed of 5 m/s, and 31.3% and 49% for the higher approaching wind speed, for the plano-convex bowl and centrally convex bowl, respectively. The centrally convex bowl seems to be more appropriate for higher approaching wind speeds. An increase in wind turbine efficiency, described by the power coefficient, for solutions with aerodynamic bowls was observed.

scholarly journals Numerical Investigations of the Effects of the Rotating Shaft and Optimization of Urban Vertical Axis Wind Turbines

Energies ◽  
2018 ◽  
Vol 11 (7) ◽  
pp. 1870 ◽  
Author(s):  
Lidong Zhang ◽  
Kaiqi Zhu ◽  
Junwei Zhong ◽  
Ling Zhang ◽  
Tieliu Jiang ◽  
...  
Keyword(s):  
Wind Turbine ◽  
Wind Turbines ◽  
Suction Side ◽  
Vertical Axis ◽  
Power Coefficient ◽  
Small Scale ◽  
Physical Parameters ◽  
Rotating Shaft ◽  
Vertical Axis Wind Turbines ◽  
Negative Effect

The central shaft is an important and indispensable part of a small scale urban vertical axis wind turbines (VAWTs). Normally, it is often operated at the same angular velocity as the wind turbine. The shedding vortices released by the rotating shaft have a negative effect on the blades passing the wake of the wind shaft. The objective of this study is to explore the influence of the wake of rotating shaft on the performance of the VAWT under different operational and physical parameters. The results show that when the ratio of the shaft diameter to the wind turbine diameter (α) is 9%, the power loss of the wind turbine in one revolution increases from 0% to 25% relative to that of no-shaft wind turbine (this is a numerical experiment for which the shaft of the VAWT is removed in order to study the interactions between the shaft and blade). When the downstream blades pass through the wake of the shaft, the pressure gradient of the suction side and pressure side is changed, and an adverse effect is also exerted on the lift generation in the blades. In addition, α = 5% is a critical value for the rotating shaft wind turbine (the lift-drag ratio trend of the shaft changes differently). In order to figure out the impacts of four factors; namely, tip speed ratios (TSRs), α, turbulence intensity (TI), and the relative surface roughness value (ks/ds) on the performance of a VAWT system, the Taguchi method is employed in this study. The influence strength order of these factors is featured by TSRs > ks/ds > α > TI. Furthermore, within the range we have analyzed in this study, the optimal power coefficient (Cp) occurred under the condition of TSR = 4, α = 5%, ks/ds = 1 × 10−2, and TI = 8%.

Numerical Simulation and Virtual Reality Visualization of Horizontal and Vertical Axis Wind Turbines

2011 ◽  
Author(s):  
Nan Yan ◽  
Tyamo Okosun ◽  
Sanjit K. Basak ◽  
Dong Fu ◽  
John Moreland ◽  
...  
Keyword(s):  
Numerical Simulation ◽  
Virtual Reality ◽  
Wind Turbine ◽  
Wind Turbines ◽  
Vertical Axis ◽  
Small Scale ◽  
Mechanical Resistance ◽  
Wind Flow ◽  
Horizontal Axis Wind Turbine ◽  
Immersive Environment

Virtual Reality (VR) is a rising technology that creates a computer-generated immersive environment to provide users a realistic experience, through which people who are not analysis experts become able to see numerical simulation results in a context that they can easily understand. VR supports a safe and productive working environment in which users can perceive worlds, which otherwise could be too complex, too dangerous, or impossible or impractical to explore directly, or even not yet in existence. In recent years, VR has been employed to an increasing number of scientific research areas across different disciplines, such as numerical simulation of Computational Fluid Dynamics (CFD) discussed in present study. Wind flow around wind turbines is a complex problem to simulate and understand. Predicting the interaction between wind and turbine blades is complicated by issues such as rotating motion, mechanical resistance from the breaking system, as well as inter-blade and inter-turbine wake effects. The present research uses CFD numerical simulation to predict the motion and wind flow around two types of turbines: 1) a small scale Vertical Axis Wind Turbine (VAWT) and 2) a small scale Horizontal Axis Wind Turbine (HAWT). Results from these simulations have been used to generate virtual reality (VR) visualizations and brought into an immersive environment to attempt to better understand the phenomena involved.

Cable Reinforced Small Scale Horizontal Axial Wind Turbine

2013 ◽  
Vol 394 ◽  
pp. 309-313
Author(s):  
Yuan Ma ◽  
Pan Zeng ◽  
Hong Ya Lu ◽  
Yue Jie Xu
Keyword(s):  
Wind Turbine ◽  
Turbine Blade ◽  
Wind Turbines ◽  
Noise Level ◽  
Wind Turbine Blade ◽  
Small Scale ◽  
Optimum Location ◽  
Reinforcement Structure ◽  
First Order ◽  
Vibration Tests

In this paper, a cable reinforcement structure for small scale horizontal axial wind turbines is proposed. Shock-vibration tests were performed on the cable reinforced structure with different parameters of cable installation. The first order frequency of the blade was chosen to represent the stiffness of the blade rotor. According to the results, an optimum location of cable reinforcement exists at around 1/3 length of the wind turbine blade, and the first order frequency of the blade rotor will rise with the tension of the cable in a certain range. Further analysis showed that besides improving the reliability of the wind turbine rotors, the cable reinforcement structure also provides a possibility to use cheaper materials for blade manufacturing and also control the noise level of small scale horizontal axial wind turbines.

scholarly journals Numerical analysis on the performance of Dual Rotor wind turbine

2020 ◽  
Vol 8 (03) ◽  
pp. 352-368
Author(s):  
Hazem Ali Abdel Karim ◽  
Ahmed Reda El-Baz ◽  
Nabil Abdel Aziz Mahmoud ◽  
Ashraf Mostafa Hamed
Keyword(s):  
Wind Turbine ◽  
Rotational Speed ◽  
Pitch Angle ◽  
Numerical Study ◽  
Three Dimensional ◽  
Scale Model ◽  
Power Coefficient ◽  
Peak Performance ◽  
Small Scale ◽  
Cfd Simulations

This study investigates the aerodynamic performance of wind turbines aiming to maximize the power extracted from the wind. The study is focusing on the effect of introducing a second rotor to the main rotor of the wind turbine in what is called a dual rotor wind turbine (DRWT).  The numerical study took place on the performance of small-scale model of wind turbine of 0.9 m diameter using S826 airfoil. Both the Co-rotating and Counter rotating configurations were investigated at different tip speed ratios (TSR) and compared with the performance of the single rotor wind turbine (SRWT). Many parameters were studied for dual rotor turbines. These include the spacing between the two rotors, the pitch angle of the rear rotor and the rotational speed of ratio rear to front rotor. Three-dimensional simulations performed and employed using CFD simulations with Multi Reference Frame (MRF) technique. The Co Rotating Wind Turbine (CWT) and Counter Rotating Wind Turbine (CRWT) found to have better performance compared to that of the SRWT with an increase ranging from 12 to 14% in peak power coefficient. Moreover, the effect of changing the pitch angle of the rear rotor on the overall performance found to be of a negligible effect between angles 0⁰ until 2⁰ degrees tilting toward the front rotor. On the other hand, the ratio of rotational speed of the rear rotor to the front rotor found to cause a further increase in the peak performance of the CWT and CRWT ranging from 3 to 5%.

scholarly journals Research on the Power Capture and Wake Characteristics of a Wind Turbine Based on a Modified Actuator Line Model

Energies ◽  
2022 ◽  
Vol 15 (1) ◽  
pp. 282
Author(s):  
Feifei Xue ◽  
Heping Duan ◽  
Chang Xu ◽  
Xingxing Han ◽  
Yanqing Shangguan ◽  
...  
Keyword(s):  
Wind Turbine ◽  
Output Power ◽  
Wind Turbines ◽  
Wind Farm ◽  
Three Dimensional ◽  
Wind Farms ◽  
Line Model ◽  
Eddy Simulation ◽  
Large Eddy ◽  
Actuator Line Model

On a wind farm, the wake has an important impact on the performance of the wind turbines. For example, the wake of an upstream wind turbine affects the blade load and output power of the downstream wind turbine. In this paper, a modified actuator line model with blade tips, root loss, and an airfoil three-dimensional delayed stall was revised. This full-scale modified actuator line model with blades, nacelles, and towers, was combined with a Large Eddy Simulation, and then applied and validated based on an analysis of wind turbine wakes in wind farms. The modified actuator line model was verified using an experimental wind turbine. Subsequently, numerical simulations were conducted on two NREL 5 MW wind turbines with different staggered spacing to study the effect of the staggered spacing on the characteristics of wind turbines. The results show that the output power of the upstream turbine stabilized at 5.9 MW, and the output power of the downstream turbine increased. When the staggered spacing is R and 1.5R, both the power and thrust of the downstream turbine are severely reduced. However, the length of the peaks was significantly longer, which resulted in a long-term unstable power output. As the staggered spacing increased, the velocity in the central near wake of the downstream turbine also increased, and the recovery speed at the threshold of the wake slowed down. The modified actuator line model described herein can be used for the numerical simulation of wakes in wind farms.

scholarly journals The Dependence of the Optimal Size of a Wind Turbine Tower on Wind Profile in Height

2019 ◽  
Vol 7 (1) ◽  
pp. 58-65
Author(s):  
Vladimirs Vorohobovs ◽  
Andrey Zakharoff
Keyword(s):  
Wind Turbine ◽  
Wind Turbines ◽  
Wind Profile ◽  
Optimal Size ◽  
Correct Decision ◽  
Common Misconception ◽  
Wind Turbine Tower ◽  
Economical Optimization ◽  
Tower Height

Abstract In this article the necessity of measuring wind at its different heights is discussed. The economical optimization of tower height is impossible without such measurement. In places where land is relatively flat, for example, in deserts or swamps, smaller wind turbines are more profitable, while in forest zones bigger turbines are more profitable. In both cases, to make a correct decision on the optimal tower height, it is very important to know exactly the wind profile law. Even for places where land is expensive, the measurement of the wind at different heights can influence the correct decision regarding the optimal size and number of needed turbines for getting the required power. For places with cheaper land, this dependence is even stronger. This analysis refutes a common misconception: “the bigger – the better”.

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