scholarly journals Urban Wind Harvesting Using Flow-Induced Vibrations

2020 ◽  
Vol 16 (4) ◽  
pp. 71-79
Author(s):  
Levon Ghabuzyan ◽  
Christopher Luengas ◽  
Jim Kuo
Keyword(s):  
Wind Tunnel ◽  
Energy Harvesting ◽  
Wind Energy ◽  
Wind Turbine ◽  
Cantilever Beam ◽  
Wind Turbines ◽  
Wind Farms ◽  
Urban Environments ◽  
The Body ◽  
Flow Induced Vibrations

The growing global interest in sustainable energy has paved the way to the rapid development of large-scale wind farms, consisting of dozens to hundreds of wind turbines. Although these large wind farms can generate enormous amount of power, they are also costly and require large areas of land or water, and thus are not suitable for urban environments. Smaller urban wind turbines have been developed for urban environments, but there are significant challenges to their widespread deployment. One of these challenges are their urban wind flows as they are strongly affected by complex building structures, producing highly turbulent flows. Any urban wind turbine would need to be designed to function efficiently and safely under these flow conditions; however, these unpredictable and turbulent winds can induce undesirable vibrations and cause early failures. Recently, bladeless wind turbines are gaining interest due to their reduced costs compared with conventional wind turbines such as the vertical-axis wind turbine and horizontal-axis wind turbine. These bladeless turbines convert flow wind energy into vibration energy, then converts the vibration energy into electricity. This paper examines the effects of force-induced vibrations on a cantilever beam system through wind tunnel experimentation. When fluid flows around a bluff body, periodic shedding of vortices may occur under the right conditions. The vortex shedding process creates an asymmetric pressure distribution on the body which causes the body to oscillate, known as vortex-induced vibrations. The purpose of the paper is to understand the factors affecting flow-induced vibrations and to improve wind energy harvesting from these vibrations. The first part of the paper focuses on wind tunnel experiments, by utilizing a cantilever beam configuration, conceptualized by previous research. Then, the experimental model was tested in different configurations, to determine the best setup for maximizing vibrations induced on the model. The long-term goal of the project was utilizing the model to optimize the system to improve efficiency of wind energy harvesting. The experimental results showed that the presence of an upstream cylinder will significantly improve the amplitude of vibration for energy harvesting, furthermore, the experiments showed that spacing in different directions also affect the amplitude of the vibrations. A two tandem cylinder system was used in this work, including a fixed rigid upstream cylinder and a downstream cylinder supported by a cantilever beam. Various configurations of these two cylinders in terms of spanwise and streamwise separation distances were studied and their maximum and root mean square displacements are reported for different wind speeds. Results showed that the presence of an upstream cylinder will significantly improve the amplitude of vibrations. This work verified that a wind energy harvester needs to consider the effects of wind speed and separation configuration of the cylinders in order to maximize the harvester’s performance in urban environments. KEYWORDS: Sustainable Energy; Energy Harvesting; Urban Environments; Bladeless Wind Turbines; Flow-Induced Vibrations; Cantilever Beam System; Wind Tunnel; Wake

Simulation of Flow Field on a Large Scale Wind Turbine

2008 ◽  
Author(s):  
I. Janajreh ◽  
C. Ghenai
Keyword(s):  
Flow Field ◽  
Wind Energy ◽  
Wind Turbine ◽  
Wind Turbines ◽  
Cross Sections ◽  
Large Scale ◽  
Wind Farms ◽  
Operating Characteristics ◽  
Cross Sectional ◽  
Capital Costs

Large scale wind turbines and wind farms continue to evolve mounting 94.1GW of the electrical grid capacity in 2007 and expected to reach 160.0GW in 2010 according to World Wind Energy Association. They commence to play a vital role in the quest for renewable and sustainable energy. They are impressive structures of human responsiveness to, and awareness of, the depleting fossil fuel resources. Early generation wind turbines (windmills) were used as kinetic energy transformers and today generate 1/5 of the Denmark’s electricity and planned to double the current German grid capacity by reaching 12.5% by year 2010. Wind energy is plentiful (72 TW is estimated to be commercially viable) and clean while their intensive capital costs and maintenance fees still bar their widespread deployment in the developing world. Additionally, there are technological challenges in the rotor operating characteristics, fatigue load, and noise in meeting reliability and safety standards. Newer inventions, e.g., downstream wind turbines and flapping rotor blades, are sought to absorb a larger portion of the cost attributable to unrestrained lower cost yaw mechanisms, reduction in the moving parts, and noise reduction thereby reducing maintenance. In this work, numerical analysis of the downstream wind turbine blade is conducted. In particular, the interaction between the tower and the rotor passage is investigated. Circular cross sectional tower and aerofoil shapes are considered in a staggered configuration and under cross-stream motion. The resulting blade static pressure and aerodynamic forces are investigated at different incident wind angles and wind speeds. Comparison of the flow field results against the conventional upstream wind turbine is also conducted. The wind flow is considered to be transient, incompressible, viscous Navier-Stokes and turbulent. The k-ε model is utilized as the turbulence closure. The passage of the rotor blade is governed by ALE and is represented numerically as a sliding mesh against the upstream fixed tower domain. Both the blade and tower cross sections are padded with a boundary layer mesh to accurately capture the viscous forces while several levels of refinement were implemented throughout the domain to assess and avoid the mesh dependence.

Atmospheric Wind Data Collection and Wind Turbine Analysis in UAE

2009 ◽  
Author(s):  
Isam Janajreh ◽  
Rana Qudaih ◽  
Ilham Talab ◽  
Zaki Al Nahari
Keyword(s):  
Wind Energy ◽  
Wind Turbine ◽  
Wind Turbines ◽  
Ecological Impact ◽  
Wind Farms ◽  
Offshore Wind ◽  
Wind Data ◽  
Gulf Region ◽  
Electrical Grid ◽  
Capital Costs

Wind turbine technology has improved dramatically in the last two decades as demonstrated by their plummeting capital costs ($0.08/KW), the enhanced reliability, and the increased efficiency. Large-scale wind turbines and wind farms provided 94.1GW of electrical grid capacity in 2007, and are expected to reach 160 GW by 2010 according to WWEA. Wind energy is plentiful and sustainable energy source with an estimated potential capacity of 72 TW. In Denmark the inland and offshore implementation of wind energy generation adds 1/5 of their electrical grid capacity. In Germany, it is forecasted to attain 12.5% by early 2010. Offshore wind farms have lower ecological impact due to lack of land mortgage, easier transportation, and low perception of noise issue. In the gulf region, the generated power can fulfill the power needs of UAE’s islands, while the excess capacity can be channeled to the inland grids fulfilling the peak demand. In this work we will investigate the implementation of low-turning moment wind turbines in the UAE, suited for low wind speeds (∼3–5m/s) and that consists of two research components: (i) Collection of wind data, analysis, recommendation for implementation strategies, and using Masdar wind data to assess its characteristics and its fit for wind turbine implementation; (ii) Carry out flow analysis on a downwind, two-bladed, horizontal-axes wind turbine to investigate the flow lift, drag and wake characteristics on the tower blade interaction. The interaction is studied utilizing Arbitrary Lagrangian Eulerian method. Downwind turbines are self-aligned, pass up yaw mechanisms and its needed power, and have fewer moving parts that necessitate regular maintenance. These factors however play in favor of wind turbine that is subjected to low wind speed.

scholarly journals Foundation Types for Land and Offshore Sustainable Wind Energy Turbine Towers

2020 ◽  
Vol 184 ◽  
pp. 01094
Author(s):  
C Lavanya ◽  
Nandyala Darga Kumar
Keyword(s):  
Wind Energy ◽  
Wind Turbine ◽  
Wind Turbines ◽  
Wind Farm ◽  
Wind Farms ◽  
Offshore Wind ◽  
Offshore Wind Farms ◽  
Wind Speeds ◽  
Deep Waters ◽  
Wind Turbine Towers

Wind energy is the renewable sources of energy and it is used to generate electricity. The wind farms can be constructed on land and offshore where higher wind speeds are prevailing. Most offshore wind farms employ fixed-foundation wind turbines in relatively shallow water. In deep waters floating wind turbines have gained popularity and are recent development. This paper discusses the various types of foundations which are in practice for use in wind turbine towers installed on land and offshore. The applicability of foundations based on depth of seabed and distance of wind farm from the shore are discussed. Also, discussed the improvement methods of weak or soft soils for the foundations of wind turbine towers.

Overview of Vertical Axis Wind Turbine (VAWT) is one of the Wind Energy Application

2015 ◽  
Vol 793 ◽  
pp. 388-392
Author(s):  
Farhan Ahmed Khammas ◽  
Kadhim Hussein Suffer ◽  
Ryspek Usubamatov ◽  
Mohmmad Taufiq Mustaffa
Keyword(s):  
Wind Energy ◽  
Wind Turbine ◽  
Wind Turbines ◽  
Rural Areas ◽  
High Efficiency ◽  
Wind Farms ◽  
Vertical Axis ◽  
Horizontal Wind ◽  
Traditional Use ◽  
Vertical Axis Wind Turbines

This paper reviews the available types of wind turbine which is one of the wind energy applications. The authors intend to give investors a better idea of which turbine is suitable for a particular setting and to provide a new outlook on vertical axis wind turbines. Wind technology has grown substantially since its original use as a method to grind grains and will only continue to grow. Vertical-axis wind turbines are more compact and suitable for residential and commercial areas while horizontal-axis wind turbines are more suitable for wind farms in rural areas or offshore. However, technological advances in vertical axis wind turbines that are able to generate more energy with a smaller footprint are now challenging the traditional use of horizontal wind turbines in wind farms. Vertical axis wind turbines do not need to be oriented to the wind direction and offer direct rotary output to a ground-level load, making them particularly suitable for water pumping, heating, purification and aeration, as well as stand-alone electricity generation. The use of high efficiency Darrieus turbines for such applications is virtually prohibited by their inherent inability to self-start.

scholarly journals Aerodynamic Analysis and Performance Prediction of VAWT and HAWT Using CARDAAV and Qblade Computer Codes

2021 ◽  
Author(s):  
Tayeb Brahimi ◽  
Ion Paraschivoiu
Keyword(s):  
Wind Energy ◽  
Wind Turbine ◽  
Wind Turbines ◽  
Large Scale ◽  
Wind Farms ◽  
Rotor Blades ◽  
Dynamic Stall ◽  
And Performance ◽  
Control Stability ◽  
Induced Velocity

Wind energy researchers have recently invited the scientific community to tackle three significant wind energy challenges to transform wind power into one of the more substantial, low-cost energy sources. The first challenge is to understand the physics behind wind energy resources better. The second challenge is to study and investigate the aerodynamics, structural, and dynamics of large-scale wind turbine machines. The third challenge is to enhance grid integration, network stability, and optimization. This chapter book attempts to tackle the second challenge by detailing the physics and mathematical modeling of wind turbine aerodynamic loads and the performance of horizontal and vertical axis wind turbines (HAWT & VAWT). This work underlines success in the development of the aerodynamic codes CARDAAV and Qbalde, with a focus on Blade Element Method (BEM) for studying the aerodynamic of wind turbines rotor blades, calculating the induced velocity fields, the aerodynamic normal and tangential forces, and the generated power as a function of a tip speed ration including dynamic stall and atmospheric turbulence. The codes have been successfully applied in HAWT and VAWT machines, and results show good agreement compared to experimental data. The strength of the BEM modeling lies in its simplicity and ability to include secondary effects and dynamic stall phenomena and require less computer time than vortex or CFD models. More work is now needed for the simulation of wind farms, the influence of the wake, the atmospheric wind flow, the structure and dynamics of large-scale machines, and the enhancement of energy capture, control, stability, optimization, and reliability.

A Conceptual Design and Modeling Approach for Determining the Revised Energy Generation Potential due to Site Obstructions for Micro-Scale Wind Turbines

2014 ◽  
Author(s):  
Keith Hurdelbrink ◽  
Zahed Siddique
Keyword(s):  
Energy Harvesting ◽  
Wind Energy ◽  
Wind Turbine ◽  
Wind Turbines ◽  
Energy Generation ◽  
Design Guidelines ◽  
Weather Data ◽  
Correction Factors ◽  
Common Site ◽  
Micro Scale

Wind energy is one of the fastest growing sectors of renewable energy technologies. Micro-scale wind turbines are becoming increasingly more popular as individuals seek more innovative and efficient ways of reducing their energy demand. However, even with more efficient wind energy harvesting devices, it is not uncommon for the anticipated energy harvesting potential for a wind turbine to be vastly different from the actual energy generation capability for a site. This paper will introduce the problems associated with accurately predicting the energy generation potential of wind energy harvesting systems considering several power loss factors. The focus of this paper is on the use of commonly available engineering tools and simulations to evaluate obstructions on the implementation site and energy harvesting technologies in order to maximize the energy generation potential. The issues of energy generation prediction accuracy will be addressed by incorporating high-resolution weather data and computer simulations into a predictive model. Additionally, several correction factors and design guidelines for the successful implementation of micro-scale wind turbines will be introduced and discussed. A multi-step approach is introduced to collect weather data, generate revised energy generation potential models for various land regions, account for common site obstructions through the use of correction factors, and formulate a final set of recommendations for the wind turbine implementation site. A set of design guidelines are also developed to assist in turbine placement for specific site locations. The guidelines are based on the revised energy generation prediction model, wind speed correction factors for common site obstructions, orientation and placement of the wind turbine, and other factors. Verification of the guidelines has been performed through Computational Fluid Dynamics simulation. The design approach and guidelines are examined and results presented for one case study.

Output wind power curve optimization based on design wind speed concept

2020 ◽  
pp. 0309524X1990100
Author(s):  
Cherif Khelifi ◽  
Fateh Ferroudji
Keyword(s):  
Wind Speed ◽  
Wind Energy ◽  
Wind Turbine ◽  
Wind Power ◽  
Wind Turbines ◽  
Wind Farms ◽  
Operating Conditions ◽  
Speed Ratio ◽  
Power Curve ◽  
Design Wind Speed

The output wind power curve versus wind speed is the most important characterization parameter of wind turbines. It allows quantifying and analyzing the design performances of wind turbines, monitoring its database, and controlling the operation modes and manufacturing products. Wind power curve can be used to select the proper rotor size to estimate the potential of wind energy at candidate wind sites and to assess the control device of the operating conditions. Developing model strategies for wind farms has the basic objectives such as the optimization of wind power produced and the minimization of dynamic loads to provide the best quality of output wind power at reasonable cost. Optimal design of wind turbines requires maximum-closing to the cubical output wind power curve despite technical and economic considerations. This study aims to determine the design wind speed of a wind turbine based on modeling-optimization of the output wind power curve under certain working conditions. The procedure is applied to a unit wind turbine in Gamesa wind farm (G52/850, 10.2 MW, http://www.thewindpower.net ) connected to an electrical grid located in south-west Algeria and extrapolated for other windy sites in Algeria. From simulation results, the design wind speed to inlet wind speed ratio [Formula: see text] increased from 0.35 to 7.68 once [Formula: see text] increased from 0.001 to 2.9999. Consequently, the output wind power predicted an increase of about 17.7% and an annual specific wind energy factor of about 2.55%–4% than nominal value given by the manufacturer, reducing the unit average cost of the electricity, generated by wind farms, by about 18.75%.

Parametric study of a fan-bladed micro-wind turbine

2011 ◽  
Vol 225 (8) ◽  
pp. 1120-1131 ◽  
Author(s):  
D Y C Leung ◽  
Y Deng ◽  
M K H Leung
Keyword(s):  
Wind Energy ◽  
Wind Turbine ◽  
Wind Turbines ◽  
Parametric Study ◽  
Cfd Simulation ◽  
Low Cost ◽  
Urban Environments ◽  
Power Performance ◽  
Wind Turbine System ◽  
Physical Experiments

The present paper investigates the performance of a special micro-wind turbine designed to capture wind energy in rural as well as urban environments. Different from traditional kilo- to megawatt size wind turbines which can be connected directly to the grid, the micro-wind turbine system is flexible in size and linked with small generators that generate electric power at the site of installation for easy applications. The main advantage of this micro-wind turbine, apart from its low cost, is that it can be propelled by a wind speed as low as 2 m/s. To extract more wind energy, several such micro-wind turbines can be connected together by their external gears into an array to increase their swept areas and hence power. In the study, the performance of a single micro-wind turbine was simulated using computational fluid dynamics (CFD) and validated through physical experiments. The experimental results on angular velocity and power developed showed a good agreement with those predicted by the CFD simulation. The validated computer model was then used for a parametric study of the wind turbine with varying blade subtend angles and number of blades, both of which affect the torque acting on the wind turbine and the power performance. The design of the wind turbine blade was optimized through the CFD simulation. This paper considers mainly the aerodynamic performance of a single turbine and issues relating to its practical deployment are not dealt with.

A systematic failure finding model of wind turbine drive train based on interfaces

2018 ◽  
Vol 15 (1) ◽  
pp. 86-90
Author(s):  
Muhammad Usman ◽  
Bilal Akbar ◽  
Sajjad Miran ◽  
Qazi Shahzad Ali
Keyword(s):  
Complex Systems ◽  
Wind Energy ◽  
Wind Turbine ◽  
Wind Turbines ◽  
Systems Engineering ◽  
Alternative Energy ◽  
Wind Farm ◽  
Wind Farms ◽  
Content Type ◽  
Gear Box

Purpose Wind energy has become a distinguished field of energy among the alternative energy resources. Despite economical disadvantages, the production of wind energy is desired to fulfill the demand of the energy. Low reliability is a big issue in the development of wind energy technology that has affected wind farm operations. The purpose of the study is to find the reason for the low reliability and high downtime for wind turbines. Design/methodology/approach The systems engineering approach has a high success rate in handling complex systems such as wind farms. A failure finding model is presented based on the systems engineering, with the focus to analyze the failures at the interfaces. The required data have been collected by reviewing the literature. Findings Gear box interfaces are a vital reason for the higher downtime and frequent failures of wind turbines, and the bearing and the lubricant in the gear box are affected because of their inappropriate combination. Originality/value The reliability and the maintainability of the wind turbine is a topic of major importance. The study is an attempt to contribute to a more sophisticated solution to the reliability problem of the wind turbine. Moreover, it shows the importance of interfaces in designing the complex systems.

SHAPING OF AN AUTONOMOUS POWER SYSTEM FOR GUARANTEED POWER SUPPLY WITH THE PREDOMINANCE WIND ENERGY

2018 ◽  
pp. 28-50
Author(s):  
S. G. Ignatiev ◽  
S. V. Kiseleva
Keyword(s):  
Energy Storage ◽  
Wind Speed ◽  
Wind Energy ◽  
Wind Turbine ◽  
Wind Turbines ◽  
Energy Demand ◽  
Diesel Generator ◽  
Average Wind Speed ◽  
Wind Speeds ◽  
Average Wind

Optimization of the autonomous wind-diesel plants composition and of their power for guaranteed energy supply, despite the long history of research, the diversity of approaches and methods, is an urgent problem. In this paper, a detailed analysis of the wind energy characteristics is proposed to shape an autonomous power system for a guaranteed power supply with predominance wind energy. The analysis was carried out on the basis of wind speed measurements in the south of the European part of Russia during 8 months at different heights with a discreteness of 10 minutes. As a result, we have obtained a sequence of average daily wind speeds and the sequences constructed by arbitrary variations in the distribution of average daily wind speeds in this interval. These sequences have been used to calculate energy balances in systems (wind turbines + diesel generator + consumer with constant and limited daily energy demand) and (wind turbines + diesel generator + consumer with constant and limited daily energy demand + energy storage). In order to maximize the use of wind energy, the wind turbine integrally for the period in question is assumed to produce the required amount of energy. For the generality of consideration, we have introduced the relative values of the required energy, relative energy produced by the wind turbine and the diesel generator and relative storage capacity by normalizing them to the swept area of the wind wheel. The paper shows the effect of the average wind speed over the period on the energy characteristics of the system (wind turbine + diesel generator + consumer). It was found that the wind turbine energy produced, wind turbine energy used by the consumer, fuel consumption, and fuel economy depend (close to cubic dependence) upon the specified average wind speed. It was found that, for the same system with a limited amount of required energy and high average wind speed over the period, the wind turbines with lower generator power and smaller wind wheel radius use wind energy more efficiently than the wind turbines with higher generator power and larger wind wheel radius at less average wind speed. For the system (wind turbine + diesel generator + energy storage + consumer) with increasing average speed for a given amount of energy required, which in general is covered by the energy production of wind turbines for the period, the maximum size capacity of the storage device decreases. With decreasing the energy storage capacity, the influence of the random nature of the change in wind speed decreases, and at some values of the relative capacity, it can be neglected.

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