Wind Tower Research Articles

Research of waterproofing screens of increased efficiency for preservation of objects of cultural heritage

The object of research is the technology of constructing waterproofing screens of buildings and structures from limestone-shell rock. The paper discusses the causes of the violation of the waterproofing of the underground parts of buildings which are made of limestone-shell rock. The problems of preservation of historical buildings and structures made of limestone-shell rock are revealed on the example of such buildings in Ukraine and Moldova: – Odessa Opera and Ballet Theatre; – House of Stratz; – Brodsk Synagogue; – House of Marazli; – Bilhorod-Dnistrovsk and Bendery Fortresses; – Tower of Winds; – Church of St. Cajetan; – Powder Cellar of the Tiraspol Fortress; – Water Mill; – Church of the Archangel Michael in the village Stroenets and many others. Based on the methods of the mathematical theory of the experiment, a complex of experimental-statistical models has been constructed, the analysis of which allowed to estimate the intensity of capillary absorption of the «waterproofing screen – limestone-shell rock» system depending on the depth of injection, the diameter of the injector and the step of its location. An arrangement of injection holes was proposed and justified to ensure waterproofing of structures, which allows filling the capillary-porous masonry space for 6–12 % more than other schemes. The accepted physical model of the distribution of the injectable composition in the porous structure of limestone-shell rock allowed to analyze the depth, diameter, and injection step, which affect the distribution area of the solution in the structural array. The depth of injection is indeed one of the most important technological characteristics in the construction of an intra-structural waterproofing screen. From a technological point of view, the degree of influence of the injection step on the intensity of capillary moisture transfer is quite high, since it directly affects the amount of active waterproofing composition in the injected thickness, as well as labor costs when performing waterproofing works. The diameter of the borehole does not significantly affect the studied parameter within the selected experimental conditions.

Field synergy analysis of pollutant dispersion in street canyons and its optimization by adding wind catchers

The microenvironment, which involves pollutant dispersion of the urban street canyon, is critical to the health of pedestrians and residents. The objectives of this work are twofold: (i) to effectively assess the pollutant dispersion process based on a theory and (ii) to adopt an appropriate stratigy, i.e., wind catcher, to alleviate the pollution in the street canyons. Pollutant dispersion in street canyons is essentially a convective mass transfer process. Because the convective heat transfer process and the mass transfer process are physically similar and the applicability of field synergy theory to turbulence has been verified in the literature, we apply the field synergy theory to the study of pollutant dispersion in street canyons. In this paper, a computational fluid dynamics (CFD) simulation is conducted to investigate the effects of wind catcher, wind speed and the geometry of the street canyons on pollutant dispersion. According to the field synergy theory, Sherwood number and field synergy number are used to quantitatively evaluate the wind catcher and wind speed on the diffusion of pollutants in asymmetric street canyons. The results show that adding wind catchers can significantly improve the air quality of the step-down street canyon and reduce the average pollutant concentrations in the street canyon by 75%. Higher wind speed enhances diffusion of pollutants differently in different geometric street canyons.

Wind profile disturbance isolation and attenuation through an UIO–LPV approach in PMSG‐based wind turbines

Wind turbines operate under random and harsh operating conditions due to several environmental factors. The main source of disturbance is the wind profile due to wind shear and tower shadow influence on the aerodynamic torque driving the system. Disturbed aerodynamic torque induces unwanted operating conditions for all wind turbines subsystems. This study proposes a novel combined unknown input observer (UIO) and linear parameter varying (LPV) approach. In a first instance an UIO approach for disturbance isolation in the input aerodynamic torque as a simple, fast and accurate method. In addition, a comparison with an Extended Kalman filter approach for disturbance isolation is introduced. Then, when the isolation occurs, an LPV controller is used as an active controller for disturbance attenuation in the speed range of the wind turbine. The LPV controller injects a current signal into the generator opposing the disturbance signature introduced by the wind profile. The aim of the UIO-LPV strategy is limiting the amount of generated current and being able to extend the amount of disturbance attenuation. The strategy is applied to a permanent magnet synchronous generator (PMSG) based wind turbine with experimental tests and results by the means of a test rig.

Simulation study for natural ventilation retrofitting techniques in educational classrooms – A case study

Building retrofitting plays a critical role in achieving sustainable development and is an efficient way to improve the indoor air quality (IAQ) of existing spaces. The IAQ in classrooms has a significant impact on the health and academic achievement of students. However, improving the IAQ of existing classrooms is challenging if minimum architectural modifications are allowed. Different natural ventilation retrofitting techniques were proposed to improve the IAQ in existing classrooms at Jordan University of Science and Technology, which is located in a hot arid region. Computer simulations were used to analyze the ventilation rate, indoor operative temperature, relative humidity, and CO2 concentration in the base Case classroom and after the implementation of the proposed retrofitting techniques. Simulation results were compared with those obtained in the base case to determine the most efficient natural ventilation retrofitting technique. The best results were obtained by using a solar chimney to assist a wind tower, which resulted in an increase in the comfort hours during the occupation time, an improvement in the average monthly ventilation rate range, a decrease in the CO2 concentration, and an improvement in the relative humidity ratio. An energy-saving of 39% would be achieved compared with the use of split unit air condition systems. Economic assessment of the proposed system using net present value indicates positive economic viability.

An Interactive Method to Analysis of the Response of the Different Reinforcement Structures of a Door Opening of a Wind Tower

The aim of this work is to present a precise numerical calculus method capable to predict the behavior of a wind turbine mast, which is characterized by an open door in its lower part in order to facilitate the access to maintenance tasks. A parametric study had been conducted in this context. The structure studied of steel tower is considered a thin cylindrical shell with constant section and thickness along its studied height. The geometry of the tower had been modeled by non-linear shell type elements. Designers use interior reinforcements to avoid local buckling and minimize the disturbance of the distribution of stress in extreme conditions. The designs adopted in the models are proposed to achieve optimized results, the minimization of the mass, the maximization of the natural frequency and the rigidity at the end of the work. Many configuration had been considered in this study, the enhancement of the gap by using a panel with variable thickness value, by longitudinal stiffeners, by combined stiffeners and finally by a stiffened panel. A numerical model had been suggested to examine a cylindrical shell behavior in compression using the Abaqus software. The obtained results demonstrate the viability and performance of the proposed approach which perfectly meets the structural requirements of the wind tower. We have observed that the stiff plate model gives reliable results to stability under extreme load. On the other hand it is economically profitable is less material needed for manufacturing, which reduces the cost.

Investigation of the natural ventilation of wind catchers with different geometries in arid region houses

The wind catcher or wind tower is a natural ventilation technique that has been employed in the Middle East region and still until nowadays. The present paper aims to study the effect of the one-sided position of a wind catcher device against the ventilated space or building geometry and its natural ventilation performance. Four models based on the traditional design of a one-sided wind catcher are studied and compared. The study is achieved under the climatic conditions of the South-west of Algeria (arid region). The obtained results showed that the front and Takhtabush’s models were able to create the maximum pressure difference (ΔP) between the windward and leeward of the tower-house system. Internal airflow velocities increased with the increase of wind speed in all studied models. For example, at Vwind = 2 m/s, the internal flow velocities were 1.7, 1.8, 1.3, and 2.5 m/s for model 1, 2, 3, and 4, respectively. However, at Vwind = 6 m/s, the internal flow velocities were 5.6, 5.5, 2.5, and 7 m/s for model 1, 2, 3, and 4, respectively. The higher internal airflow velocities are given by Takhtabush, traditional, front and middle tower models, respectively, with a reduction rate between the tower outlet and occupied space by 72, 42, 36, and 33% for the middle tower, Takhtabush, traditional tower, and the front model tower, respectively. This reduction is due to the due to internal flow resistance. The third part of the study investigates the effect of window (exist opening) position on the opposite wall. The upper, middle and lower window positions are studied and compared. The air stagnation or recirculation zone inside the ventilated space reduced from 55% with the lower window to 46% for the middle window and reached 35% for the upper window position. The Front and Takhtabush models for the one-sided wind catcher with an upper window position are highly recommended for the wind-driven natural ventilation in residential houses that are located in arid regions.

Estudo de viabilidade para a reutilização de plataformas offshore fixa como substrutura de torres eólica

Com o objetivo de dar um outro uso às plataformas offshore fixa com o tempo de vida útil vencidas, principalmente aquelas situadas em campos com condições ambientais favoráveis para instalação de turbinas eólicas offshore, o presente trabalho de pesquisa ressalta a importância de avaliar a possibilidade de reutilização de uma plataforma (jaqueta) submetida ao carregamento de uma torres de 10 MW, considerando sobre tudo as novas condições de operação. Para isso se tem em conta as análises dos elementos que conformam a estrutura (jaqueta) de modos a atinar as suas respetivas razões de tensões. Considerou-se o carregamento da torre eólica de maneira pontualmente distribuído sobre os 4 nós no topo das pernas principais da jaqueta. A estrutura investigada apresenta uma jaqueta de 16,85 m de altura, com a área da mesa inferior de 9,95 m x 9,95 m e 6,75 m x 6,75 m na mesa superior. O sistema estrutural foi desenvolvido com base à utilização do software OrcaFlex V10.3, que permite analisar as razões de tensões (“Unity Check”) incluído os efeitos de segunda ordem por meio da utilização do Método dos Elementos Finitos (MEF). Desta forma, os resultados obtidos ao longo das análises para avaliar o comportamento estrutural apontam para o fato de que a jaqueta investigada não atende aos critérios de projeto para dar suporte a torres eólicas de 10 MW.

Analysis of traditional windcatchers and the effects produced by changing the size, shape, and position of the outlet opening

Increased thermal comfort in buildings is consuming large amounts of energy around the world, especially in hot arid and semi-arid regions. Finding and adapting ways to naturally cool buildings should be a priority for researchers in the subject. For centuries the Middle East cultures have used wind towers to cool their buildings and they have proved to be a cost-effective, easy to implement and reliable solution for passive cooling that requires almost negligible energy to operate. The present work tests one traditional windcatcher and 33 modifications of the design of the outlet opening. It seeks to act as a guide to how both to enhance and also avoid reducing performance when designing windcatchers with traditional designs. Using CFD modelling, the volumetric airflow that was captured by the catcher was computed for the different outlet modifications, and this revealed which designs restrain the flow and which boost the airflow, making the wind towers more effective.

New passive thermal comfort system using three renewable energies: Wind catcher, solar chimney and earth to air heat exchanger integrated to real‐scale test room in arid region (Experimental study)

New passive thermal comfort system using three renewable energies: Wind catcher, solar chimney and earth to air heat exchanger integrated to <scp>real‐scale</scp> test room in arid region (Experimental study)

Augmented Kalman filter with a reduced mechanical model to estimate tower loads on a land-based wind turbine: a step towards digital-twin simulations

Abstract. This article presents an application of the Kalman filtering technique to estimate loads on a wind turbine. The approach combines a mechanical model and a set of measurements to estimate signals that are not available in the measurements, such as wind speed, thrust, tower position, and tower loads. The model is severalfold faster than real time and is intended to be run online, for instance, to evaluate real-time fatigue life consumption of a field turbine using a digital twin, perform condition monitoring, or assess loads for dedicated control strategies. The mechanical model is built using a Rayleigh–Ritz approach and a set of joint coordinates. We present a general method and illustrate it using a 2-degrees-of-freedom (DOF) model of a wind turbine and using rotor speed, generator torque, pitch, and tower-top acceleration as measurement signals. The different components of the model are tested individually. The overall method is evaluated by computing the errors in estimated tower-bottom-equivalent moment from a set of simulations. From this preliminary study, it appears that the tower-bottom-equivalent moment is obtained with about 10 % accuracy. The limitation of the model and the required steps forward are discussed.

Effects of different types of entrances on natural ventilation in a subway station

In this study, the natural ventilation of a horizontal entrance of a typical subway station is investigated based on numerical simulations and experiments. In addition, a renormalization group k-ɛ model (RNG k-ɛ model) is applied to compute both the internal and external airflow patterns. Computational fluid dynamics (CFD) simulations are validated based on the experimental results. Furthermore, a multiple variable regression model is employed to study how the different parameters affect the internal airflow rates of the subway station statistically, according to the experimental results. For this typical model, the parameter importance can be ranked as follows: (1) outdoor wind speed; (2) flow resistance of the subway station; (3) height of the wind catcher; and (4) length of the wind catcher. To understand the detailed pressure distribution of the horizontal entrance of the subway station with and without the wind catcher, 3D numerical simulations are conducted for different scenarios. We attempt to alter the size of the wind catcher (including the length and height) to study the characteristics of the pressure on the horizontal entrance of the subway station under outdoor wind-driven conditions. The pressure distributions for the entrance for different scenarios are compared and analyzed. Finally, the interactions between the internal and external flows are investigated by changing the resistance of the subway station. When the internal flow resistance is changed, the pressure coefficient (Cp) of the entrance is different as well. Hence, the Cp is not only affected by the outdoor environment, but is also influenced by the internal airflows.

Investigation on a Shallow Water Annular Tuned Liquid Damper for Suppressing Vibration of Wind Tower

Although the annular tuned liquid damper (ATLD) filling with shallow water is helpful in mitigating the vibration response of wind tower, it’s challenging in predicting the interface force between the ATLD and its supporting system and evaluating the damping contribution of the ATLD to the dynamic response of tower. In this study, we developed an approach to investigate the damping performance of the ATLD base on the cooperation between the smoothed particle hydrodynamics method (SPH) and the equivalent tuned mass damper model (TMD). Herein the SPH method is employed to numerically investigate the non-linear behaviour of sloshing waves in the damper and calculate the interface force, while the TMD method is used to express the TLD properties. Based on this approach, a series of numerical simulations of liquid sloshing in a shallow water ATLD with different excitation periods are carried out. The equivalent damping ratios of ATLD are calculated to quantitatively analyse the suppression effect of ATLD on the vibration response of a wind tower.

New and innovative wind catcher designs to improve indoor air quality in buildings

Wind catchers used in various countries in Middle East and North Africa in order to improve indoor air environment and to reduce reliance on cooling load. However, nowadays they are used across the globe with modern shapes and advanced techniques. The study focuses on investigating new and innovative shapes of wind catchers to improve air speed indoors which will elevate indoor comfort and air quality in buildings. The study used computer modeling CFD and a real model experiment to conduct the study. The study highlighted that curved shapes have highest pattern of wind speed driven, especially curved shape with double inlets. In addition, the study showed that octagon shape has the lowest pattern of wind speed driven because of its various sides which prevent air to flow easily inside the tunnel.

Development of a natural ventilation windcatcher with passive heat recovery wheel for mild-cold climates: CFD and experimental analysis

Abstract User demand for increased internal thermal comfort conditions have resulted in rising energy costs for space-heating consumption. The present study aims to recover the thermal energy in ventilation exhaust air and transfer the energy to the incoming air, to be redistributed using natural ventilation windcatcher. A comprehensive review was carried out to explore heat recovery systems that can potentially be incorporated with natural ventilation wind catchers. A rotary heat recovery device suitable to be incorporated with a roof mounted multi directional windcatcher system was developed. Computational Fluid Dynamics (CFD) modelling and laboratory experimental tests were conducted to investigate the proposed system. In the first phase, a full-scale prototype of the passive rotary thermal wheel device was developed and tested in a crossflow channel to initially assess the concept and performance of the design. Two configurations of the passive heat recovery wheel were tested: 20 and 32 radial blades. The second phase focused on investigating the integration of heat recovery wheel into a windcatcher system. CFD modelling and scaled wind tunnel testing were conducted to assess the airflow and temperature distribution around the multi-directional windcatcher with a passive rotary wheel. The results showed that the addition of the heat recovery wheel rotating at 15 rpm reduced the indoor airflow speed between 14 and 30%, depending on the outdoor wind conditions. The system was able to provide the recommended fresh air rates when the outdoor wind speed was 1.5 m/s and higher. In addition to sufficient ventilation, the heat recovery system had a positive impact on the indoor air temperature, raising the temperature up to 3.7 °C depending on the indoor/outdoor conditions.

Numerical investigation of the integration of heat transfer devices into wind towers

The purpose of this study is to incorporate heat transfer devices inside the passive terminal of a wind tower unit, highlighting the potential to achieve minimal restriction in the external air flow stream while ensuring maximum contact time, thus optimising the cooling duty of the device. Computational Fluid Dynamics (CFD) was used to develop a numerical model of a wind tower system and simulate the air flow pattern around and through the device to the test room. Results have indicated that the average internal airflow rate was reduced following the integration of the vertical and horizontal heat transfer device configuration, reductions of 4.11 % and 8.21 % was obtained respectively. Furthermore, the proposed cooling system was capable of reducing the air temperatures by up to 15 K. The technology presented here is subject to IP protection under the QNRF funding guidelines.

Study of wind towers with different funnels attached to increase natural ventilation in an underground building

Finding ways to cool buildings by natural, passive techniques is crucial in the context of global warming. For centuries, wind towers (traditional windcatchers) have been used in the Middle East for cooling purposes. In this study, the use of funnels at the openings of wind towers for wind ingress and egress is proposed primarily to increase the mass flow captured by the wind tower. The use of funnels in the wind ingress openings increases the inlet area, improving the capture of wind. In parallel, the use of funnels in the egress openings modifies the wake of the tower, which aims to ease the exit of the flow from inside the building. Several design configurations are presented, where the length and width of the funnels are changed and tested separately by computational fluid dynamics (CFD). Results of over 120 CFD simulations are presented and compared. The volumetric flow entering the wind towers increases by 10.7% in several cases. These results indicate that adding funnels to wind towers could positively influence their performance. Changing the dimensions of the funnels affects their efficacy and can increase or decrease the airflow entering the tower.

FUNCTIONALISM OF WIND RENEWABLE ENERGY IN VERNACULAR ELEMENTS OF WIND CATCHER AND MOSHABAK (CASE STUDY: QESHM ISLAND)

Qeshm, an island in southern Iran, has two significant elements of sustainable architecture—wind catcher and Latticework (Moshabak). So, it can be defined based on its performance-oriented vernacular architecture which results in the wind renewable energy. However, there are few studies on these sustainable elements. The present study attempted to analyze the performance and structure of these natural ventilation systems in the island. In our research methodology, we tried to use the qualitative approach. Initially, we used citation and library sources for gathering information. Later, we visited the site and the native architecture of the island was studied by analyzing and extracting architectural elements from 48 old buildings which are over 70 years old. Moreover, different types of wind energy and Moshabaks used in the island were thoroughly studied. Meanwhile, the temperature during different periods was compared and the height of the wind catchers and their influence on the rate of wind deflector, functional art, and ecology-oriented architecture of the island were evaluated. The results showed that in terms of function, these so-called sustainable native architectural elements have met the natural ventilation requirement appropriately. &#x0D; &#x0D;

FUNCTIONALISM OF WIND RENEWABLE ENERGY IN VERNACULAR ELEMENTS OF WIND CATCHER AND MOSHABAK (CASE STUDY: QESHM ISLAND)

Qeshm, an island in southern Iran, has two significant elements of sustainable architecture—wind catcher and Latticework (Moshabak). So, it can be defined based on its performance-oriented vernacular architecture which results in the wind renewable energy. However, there are few studies on these sustainable elements. The present study attempted to analyze the performance and structure of these natural ventilation systems in the island. In our research methodology, we tried to use the qualitative approach. Initially, we used citation and library sources for gathering information. Later, we visited the site and the native architecture of the island was studied by analyzing and extracting architectural elements from 48 old buildings which are over 70 years old. Moreover, different types of wind energy and Moshabaks used in the island were thoroughly studied. Meanwhile, the temperature during different periods was compared and the height of the wind catchers and their influence on the rate of wind deflector, functional art, and ecology-oriented architecture of the island were evaluated. The results showed that in terms of function, these so-called sustainable native architectural elements have met the natural ventilation requirement appropriately. &#x0D; &#x0D;

Research on Offshore Short-term Wind Speed Prediction Based on the CSA Modeling Improved by Random Algorithm

Aiming at improving the prediction accuracy of offshore short-term wind speed, a model based on random cuckoo search algorithm (RCSA) and artificial neural network (ANN) was proposed. Firstly, RCSA was obtained by introducing a random factor to improve CSA, and then a RCSA-ANN model for predicting offshore short-term wind speed was established. Secondly, a wind tower was built in Luchao Port, Shanghai, offshore meteorological data were measured, and the training of the model was carried out. Finally, the precision of RCSA-ANN model was verified by comparison and analysis with BP-ANN and CSA-ANN models. The results show that the improved CSA method is simple, reliable and effective, which solves the problem that the algorithm is easy to fall into local optimum. The average error of RCSA-ANN model is not only lower than that of BP-ANN model, but also much lower than that of CSA-ANN model, and the prediction accuracy of these three models decreases in turn. RCSA-ANN model has high prediction accuracy and can precisely predict fluctuating wind speed sequences, and it also has good application potential.

A review of wind-turbine structural stability, failure and alleviation

Advancements in materialistic life styles and increasing awareness about adverse climatic changes and its negative effects on human life have been the driving force of finding new and clean sources of energy. Wind power has become technologically mature and commercially acceptable on global scale. However, fossil fuels have been the major sources of energy in most countries, renewable energy (particularly wind) is now booming worldwide. To cope with this wind energy technology, various related aspects have to be understood by the scientific, engineering, utility, and contracting communities. This study is an effort towards the understanding of the (i) wind turbine blade and tower structural stability issues, (ii) turbine blade and tower failures and remedial measures, (iii) weather and seismic effects on turbine blade and tower failures, (iv) gear box failures, and (v) turbine blade and tower failure analysis tools.