Wind Tower Research Articles

Experimental study on the properties of Alfa/wool woven fabrics reinforced epoxy composite as an application in wind turbine blades

Wind energy is the kinetic energy of wind transformed into electrical energy by a system known as a wind turbine. All of the different parts of a wind turbine, like blades, hub, gearbox, nacelle, and tower, blades are usually made of glass and carbon fibers for better strength, lower weight, and better resistance to corrosion. The main limitations of these materials are the availability, non-biodegradable, health hazards, and fabrication cost. The development of interwoven fabric based on natural fiber for composite production is a novel approach that can be adopted to address the challenges of the balanced mechanical properties of composites. In this paper, alfa and wool fibers were selected as reinforcing materials to develop four woven fabrics, and unsaturated low viscosity epoxy resin was chosen as the matrix, the wovens were produced using the weaving of taffetas technique. The vacuum molding process was adopted to produce the hybrid composite due to its superior advantages over the hand lay-up technique. Alfa fibers have been previously treated with various concentrations of NaOH (1, 2, 3 mol) for 2 h. The effect of the alkaline treatment on the interface fiber matrix is analyzed. The results of static tests on composites showed an improvement in the tensile and flexural strengths of composites reinforced with woven fabrics. The mechanical performances of Alfa/wool yarns and fabrics obtained allow us to predict the actual perspectives of substitution of glass fibers by natural fibers for the application in wind blades.

Use of Artificial Neural Networks and Response Surface Methodology for Evaluating the Reliability Index of Steel Wind Towers

The estimation of structural reliability is a process that requires a large number of computational hours when statistical data are not available since it is necessary to perform a large amount of analysis or numerical simulations to estimate parameters related to the reliability. A methodology is proposed for estimating the structural reliability index, as well as the demand and structural capacity factors inherent to the structure, given the fundamental vibration period and the height of the structure, by using artificial neural networks (ANN) and, alternatively, the response surface method (RSM). Both approaches are applied to steel wind turbine towers. For the cases studied, ANN allow evaluating the reliability index and both the demand and structural capacity factors with greater accuracy than when using RSM.

Impact of inlet and outlet opening height variation on the air quality and ventilation efficiency in the on-top wind catcher buildings: A CFD simulation

This paper examines the role of wind-catcher height on the quality of ventilation inside the building. The base sample in this study includes a single-zone isolated building combined into a one-sided wind catcher as an inlet. Difference between inlet and outlet opening height is considered as an independent variable and ventilation quality and efficiency are considered as dependent variables. The results showed that by increasing the height of opening as a wind-catcher in the inlet facade, the airflow rate increases, the velocity decreases and the age of air increases. By increasing the height of the outlet opening, as a window from the floor to the ceiling of the room, there is no noticeable change in mean velocity, mean age of air and airflow rate. However, by transforming the outlet opening form a window to an on-top wind-catcher, the mean velocity and airflow rate decrease and the mean age of air increase. Also, by increasing the height of the wind catcher on the outlet facade, the ventilation efficiency increases too. High-resolution 3D steady RANS CFD simulations of cross ventilation are performed for all case studies.

Anti-Wind Experiments and Damage Prediction of Transmission Tower under Typhoon Conditions in Coastal Areas

Typhoons are a serious threat to transmission towers and lines in coastal areas. The anti-wind performance of a transmission tower needs to be reinforced and optimized to avoid tower collapse. Here, an improved real-time wind-field mathematical model and a tower-line coupled simulation model were established to reproduce the wind field distribution, mechanical vibration, and interaction between the wind field and tower. The damage prediction of the transmission tower was analyzed. Furthermore, an actual scaled tower-line model was built, which was used to measure the acceleration and displacement responses in the anti-wind experiments. The research results show that the improved model is feasible and correct based on the verification of Typhoon Mujigae. The tower’s vibration response is mainly characterized by low frequencies, whereas the lines indicate a high frequency response. The transmission line has a remarkable impact on tower vibrations in high turbulence. A flow direction angle of 50° and a long span are dangerous conditions for transmission systems in coastal regions. The acceleration and displacement responses of the main bars show opposite trends to that of the auxiliary cross-bars. The contribution of this article is the possibility of tower collapse prediction and prevention.

Aeroelastic Stability Analysis of a Quad-Rotor Wind Turbine

This paper presents the aeroelastic stability analysis of a quad-rotor wind turbine and identifies modes with low damping that are otherwise not present on a single-rotor wind turbine. The non-linear dynamics of a wind turbine model in SIMPACK, without considering wind shear and tower shadow, is linearized around a steady-state; followed by MBC transformation resulting in LTI model. Standard eigenvalue analysis of LTI model is carried out to capture the natural frequency and damping of a quad-rotor wind turbine as a function of wind speed. Results show that several modes with low damping (besides the low damping modes observed on a single-rotor wind turbines) are identified where the damping ratio is less than 1% over the entire operation range.

Collision Behavior Comparison of Offshore Wind Tower as Type of Support Structure

본 논문에서는 한국의 서남해상에 건설예정인 해상풍력발전타워의 지지구조물로 고려되고 있는 세발구조와 자켓구조의 선박충돌 거동을 비선형동적해석을 통하여 비교‧분석하였다. 이 구조물은 3MW용량의 풍력타워를 지지하기 위하여 설계되었다. 두 지지구조는 쉘요소를 이용하여 비선형 거동을 고려할 수 있도록 모델링하였고, 발전기를 포함하는 상부의 타워구조물은 탄성재료를 이용하여 보요소와 집중질량으로 모델링하였다. 전체 질량은 세발구조가 자켓구조에 비하여 약 1.66배 정도였다. 바지선과 상선을 충돌선박으로 선정하여 모델링하였다. 조수차의 조건을 고려하여 충돌선박의 충돌위치를 평균해수면의 상하로 3.5m변동하는 것으로 고려하였다. 또한 각 선박의 최소충돌속도(=2.6m/s)에서의 충돌에너지를 각각 4배까지 증가시키면서 충돌거동을 산정하였다. 해석결과 지지구조 충돌부위의 강성이 클수록 선박의 소성에너지 소산량이 상대적으로 증가하였다. 충돌조건에 따라 풍력타워의 변형은 진동에서 붕괴까지 발생하였다. 세발구조가 자켓구조에 비하여 큰 충돌저항력을 보였다. 이는 중앙부에 강성이 집중된 구조적 특성과 상대적으로 많은 강재의 사용량에 기인한 것으로 판단된다.

Inward and Outward Opening Properties of One-Sided Windcatchers: Experimental and Analytical Evaluation

Vernacular measures, such as courtyard, wind catcher “Malqaf”, wooden lattice “Mashrabia”, and lantern—which can help buildings to depend on natural energy from the sun and the wind—have started to be abandoned in the last decades. However, wind pressure and stack effects are becoming more popular in modern buildings design and the primary method in most domestic buildings to achieve the desired cross ventilation and minimize the air temperature to reach the required cooling loads. This paper aims to revive one of the vernacular measures “the windcatcher”, quantifying the effectiveness of the inward/outward opening properties on the air temperature and airflow inside the buildings. Analytical literature review, context analysis, and numerical simulations are performed. The computer fluid dynamics (CFD) is utilized to simulate both the temperature distribution and the flow field within the windcatcher model. Simulations are carried out in the fluent environment, which uses the control volume method for solving the conservation law. The Reynolds-averaged Navier–Stokes (RANS) and energy equation with the realizable k-ϵ turbulent model are employed. The research uses a parametric analysis to test different scenarios of windcatcher designs in terms of dimensions, proportions, and opening ratios. The results of this study confirm that windcatcher has a significant effect in lowering the air temperature inside the different floors. However, it is recommended to use a wind-catcher for not more than two floors, increase the area of the outward opening to 200% relative to the inward opening and apply side opening in the upper floors.

Development of a wind catcher for high-rise apartments in the hot-humid climate of Indonesia

This study aims to develop a new device, “cross-wind catcher”, for mid-to-high-rise affordable apartments for improving the ventilation performance in the tropics, where the natural ventilation is considered essential. We conducted a primary simulation study to find optimum wind catchers, followed by a field experiment using a full-scale experimental building to confirm the effects of the proposed device. The results showed that the proposed cross-wind catcher was able to increase the ACH by approximately 1.2 to 1.4 times compared with the control unit.

A Novel Synchronous Type Variable Speed Wind Turbine and Its Control Strategy Study

Compared with traditional power plants, current main stream wind turbines vary in grid connection interfaces, resulting in deficiencies like weak grid voltage and frequency support capability. In order to solve the problem, a synchronous type variable speed wind turbine is proposed in this paper. The wind turbine has the advantages such as the intrinsic properties of maintaining grid voltage and frequency, no harmonic pollution on grid, black start capability. In the wind turbine drive train, an electrically excited synchronous generator is directly coupled to the grid. A power self‐balance type electromagnetic coupling device is used to connect the synchronous generator rotor shaft and a gearbox high speed shaft. The device is composed of a permanent magnet synchronous generator (PMSG), a back‐to‐back converter and an electromagnetic coupler. The converter with small capacity, supplied by the PMSG which is coaxial with the gearbox high speed shaft, is used to apply the electromagnetic torque of the electromagnetic coupler. The matching relationship between the electromagnetic torque and the turbine mechanical torque, and the power flow in the drive train in different wind speeds are analyzed. Control strategies are proposed for the wind turbine normal operation including start, stop, maximum wind power capture, and low voltage ride through (LVRT). Compared with the main stream wind turbines, blade and tower loads can be improved greatly during LVRT. A 2 MW wind turbine model is built in Matlab/Simulink to verify the control strategies proposed and the wind turbine excellent LVRT performance. © 2022 Institute of Electrical Engineers of Japan. Published by Wiley Periodicals LLC.

Numerical analysis of passive toroidal tuned liquid column dampers for the vibration control of monopile wind turbines using FVM and FEM

The toroidal tuned liquid column damper (TTLCD) is a recently developed multidirectional vibration control device. This paper investigates the TTLCD for the vibration control of monopile fixed-bottom offshore wind turbines. The TTLCD with its circular versatile configuration can match the geometrical shape of wind towers and be tuned to control wind, wave and earthquake induced flexural tower vibrations. An effective numerical framework accounting for the liquid flow and sloshing as well as two-way fluid–structure interaction is developed for the TTLCD-structure system. Its accuracy is validated by comparing the numerical results with experimental ones. The design procedures of the TTLCD for monopile wind turbines are illustrated in detail. The control performance of the TTLCD under wind, wave and seismic loads is presented. The results show that the TTLCD can control the structural responses in both fore-aft and side-side directions simultaneously. Furthermore, it is revealed that for wind-induced vibrations, the control performance relies on the wind velocities and the related frequency components.

A data-based model for condition monitoring and maintenance planning for protective coating systems for wind tower structures

The application of protective coating systems is the major measure against the corrosion of steel structures for onshore wind turbines. The organic coatings are, however, susceptible to atmospheric exposure and tend to deteriorate during the operation. At the same time, onshore turbines become more powerful and require taller and more resistant tower structures. The inspection and condition monitoring of protective coating systems on large onshore turbines (in excess of 120 m height) is a demanding and time-consuming procedure and requires high human effort. The rapid developments in digitization and data analysis offer opportunities to notably increase the efficiency of monitoring processes and to develop (semi-)automated standardized procedures. The paper describes a data-oriented approach to utilize digital data for the monitoring and maintenance planning of surface protection systems of large onshore wind turbines. The proposed approach includes the following steps: the segmentation of an existing wind power structure into a number of reference areas based on an In-situ Virtual Twin; the definition of a local deterioration degree for each individual reference area; the annotation of image data; the use of heterogenous multi-modal data (image data, geodetical data, meteorological data, profile scanning data) as the sources for condition assessment and monitoring. An example procedure is exercised for a tower structure of an onshore wind power turbine in order to illustrate the practical relevance of the approach.

Layers of Meaning and Evolution of Cultural Identity: The Case of Wind Towers in Dubai

Place identity is an important constituent of general cultural identity, in that it provides its share of continuity, sustainability, and character to the built environment. The image of cultural heritage is stored knowledge that reflects the identity of a specific culture. In the formation of a place, some features gain identity with the environment. This study aims to explore the evolving image formation of wind towers in Dubai, and how this image is related to the concept of meaning and cultural identity of the place. This study focuses on the process of place identity formation and its relation to the evolving cultural values of society, as well as how it is applied to the changing meaning of cultural heritage objects. Based on the value assessment approach, different examples of wind towers, taken from either traditional houses or contemporary buildings influenced by the local architecture in Dubai, the author attempted to study how the interpretation and meaning of wind towers has evolved through time, thus influencing the cultural identity of Dubai city. This study is based on qualitative research. It concludes that a wind tower, as a cooling device, represents a unique example of an evolving creative process of architectural expression, resulting from the social and cultural complexity of the Persian Gulf in the early twentieth century. They were introduced through commercial exchange, adapted by the mercantile community, and integrated into local cultural systems—thus creating new architectural features and urban character—and reintroduced as a modern symbol of cultural identity for Dubai and the UAE.

Improving Energy Efficiency by Utilizing Wetted Cellulose Pads in Passive Cooling Systems

The effectiveness of using wetted cellulose pads on improving the performance of two conventional passive cooling systems has been evaluated. First, an experimental design was developed to determine the impact of using a wetted cellulose pad on the temperature and velocity of the airflow. A cellulose pad (7090 model) with a cross-sectional area of 0.5 × 0.5 m2 and three different thicknesses of 10, 15, and 30 cm were selected and tested. The results indicated that using wetted cellulose pads with thicknesses ranging from 10–30 cm decreased the outlet airflow temperature from 11.3 to 13.7 °C on average. For free airflow at velocity 3.5 m/s, the outlet airflow velocity from the wetted cellulose pad decreased to 0.9, 0.7 and 0.6 m/s, respectively, for cellulose pads with thicknesses of 10, 15, and 30 cm. By applying experimental results on a psychrometric chart, the humidity ratio of outlet airflow was obtained between 40–70%. The study established airflow velocity as the critical parameter in passive cooling systems. With the novel concept of combining wetted cellulose pads for passive cooling systems (i.e., wind catchers and induced ventilation), there is good potential to reduce the energy requirements for thermal comfort in buildings in regions with a hot and arid climate.

Finite element analysis of the flange with different fillet radius in tubular wind tower

Today’s modern world has more demand for electricity to perform most of the activities. In this regard, wind turbines are used to convert the wind energy into electrical power, where turbines are mounted at the top of the tower called wind tower. To meet the high power generation demand, the wind energy towers will have to become taller because winds are stronger at higher altitudes. In the present, work Modal analysis of the wind tower is done using ANSYS, and Campbell diagram is plotted to check the frequency of resonance between the tower natural frequency and the natural frequency of the rotating blades. Considering the different fillet radius in the flanges, the critical conditions are simulated under the same loading condition. Finite Element Analysis (FEA) results show that by increasing the fillet radius the Equivalent stress, Maximum principle stress and, Maximum shear stress decreases. The safety of the tower is ensured through the Campbell diagram where the excitation frequency of any blade is not crossing the exciter box.

Restoration of Wind Speed in Qinzhou, Guangxi during Typhoon Rammasun

In 2014, Typhoon Rammasun invaded Qinzhou, Guangxi, causing damage to the wind tower sensor at 80 m in Qinzhou. In order to restore the wind speed at 80 m at that time, this paper was based on the hourly average wind speed data of the wind tower and meteorological station from 2017–2019, and constructed the wind speed related model of Meteorological Station and the wind measuring tower in Qinzhou, Moreover, this paper Based on the hourly average wind speed data of Qinzhou Meteorological Station in 2014, Restored the hourly average wind speed of the anemometer tower during Rammasun landfalled. The results showed it is significant correlation that the hourly mean wind speed of the wind tower at 80 m and the hourly mean wind speed of meteorological station at 100 m (R2 = 0.9632), and speed of the wind measuring tower and speed of meteorological station constitutes an equation, This equation is Y = 0.7834X. The hourly average wind speed of the wind tower at 80 m during the 2014 Rammasun Landing was restored using this model. See the results in Schedule 4.

Impact of Actual Wind Speed Distribution on the Fault Characteristic of DFIG Rotor Winding Asymmetry

Studies show that in industrial wind turbines (WTs), the wind speed may significantly vary across the rotor disk area. This variation may originate from different parameters, including wind shear (WS) and tower shadow (TS), which affect the mechanical load and the generated electrical power. However, the influence of wind speed variation on the fault characteristics of WTs has rarely been investigated so far. As an improvement, this study made an attempt to investigate the impact of spatiotemporal distribution (STD) of wind speed on the fault characteristic of the doubly fed induction generator (DFIG). The primary contribution of this article lies in two aspects: 1) establishment of a new equivalent wind speed (EWS) model comprehensively considering the affecting parameters, including WS, TS, and turbulence, and 2) reanalysis of the rotor winding asymmetry (RWA) fault characteristics under EWS, and thus new characteristics of fault were obtained. Simulations and experiments were also carried out to evaluate the accuracy of the theoretical analysis. The obtained results reveal that in addition to the original characteristic frequency, which is correlated with RWA fault, other modulation frequencies are also correlated with wind speed distribution. It is concluded that the RWA fault characteristics of DFIG are different from those of the ordinary induction generator considering the STD of the wind speed. Importantly, the obtained results are expected to improve the fault diagnosis of DFIG.

Evaluating daylighting effectiveness of a traditional house in tropical climate

Sustainable Day lighting is crucial for enhancing visual comfort indoors, which helps to reduce energy consumption on artificial lighting and so improves the psychological well-being of the residents. Various research on sustainable daylighting have been undertaken, but little emphasis has been placed on vernacular architecture, which is the outcome of hundreds of years of optimisation in creating a comfortable shelter utilising accessible materials and established construction techniques. This climate responsive design is being lost to universal architecture in emerging countries such as India owing to modernity. Therefore, this paper tries to evaluate the performance of sustainable day lighting techniques of four different typologies of roofs of traditional houses in Tamil Nadu, India. The study qualitatively and quantitatively examines the climate, geographical location and evaluates the total number of door and window openings and calculates the Window to wall ratio, uniformity ratio, threshold values and average daylight factor. The Quantitative evaluation has been carried out using simulation (DESIGN BUILDER) and experimental method (Illuminance meter) for all the four typologies. The study found that the Wind catcher houses, courtyard houses and clear storey houses achieved visual comfort than the Tiled roof houses. However, Clerestory house achieves the needed threshold value and average daylight factor with uniform spread of daylighting thereby achieving visual comfort without glare. Thus, this study will help us to identify the best typology in terms of achieving visual comfort and the final recommendations will be used by the architects to create sustainable day lighting strategies in modern buildings using solutions from vernacular houses which is usually a deserted area of research.

Research on Ultra-short term Forecasting Technology of Wind Power Output Based on Wake Model

The concept of sustainable development promotes the development of new energy power generation industry. At the same time, in the field of wind power, wind curtailment and power limit gradually appear, and the output prediction of power plants has become one of research hotspots. Because of the wake effect between wind farms, the wind speed of the wind tower can not represent the real numerical value. Therefore, in this paper, we established various wake models of wind farm group under different wind direction to modify the wind speed of wind tower and get more accurate results. We also used the Long Short-Term Memory network (LSTM) to forecast the wind farm output, and finally obtained excellent forecast results. Compared with traditional prediction algorithm, it had improved the prediction accuracy.

Passive Heat Recovery Wind Tower: Assessing the Overheating Risk in Summertime and Ventilation Heat Loss Reduction in Wintertime

Passive Heat Recovery Wind Tower: Assessing the Overheating Risk in Summertime and Ventilation Heat Loss Reduction in Wintertime

Traditional Islamic House (Ottoman House) Architecture, in Old Fatimid Cairo and Rosetta Cities, Egypt - An Example of Sustainable Architecture

The unique Traditional Islamic architecture characterizes some cities in the Arab Republic of Egypt. The purpose of the study is to highlight the significance of the Traditional Islamic house design, architectural elements, and the use of low-technology in house construction concerning sustainable architecture, in Old Fatimid Cairo and Rosetta (Rashid) cities. The study's method includes a literature review; with an overview of the history, the urban form, and the Islamic house design and architectural elements influenced by the local Islamic context (natural and cultural environments). A field survey included: the selection of eleven examples, five from Old Fatimid Cairo city and six examples from Rosetta (Rashid) city representing the most famous houses including the different architectural elements, and analyzing its components, the house design, spatial organization, building materials, house elements, courtyard, Mashrabiyah, wind catchers, and the construction system. Moreover, a comparative study for the selected Islamic houses illustrates the contexts' impact on the house design. In conclusion, the study highlighted the significance of Islamic house design and low-technology in house design and construction, which could be considered sustainable architecture and developed in the form of advanced technology in the future.