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This paper investigated using spoilers to improve the aerodynamic characteristics of vertical-axis wind turbines. Taking the NACA0012 airfoil as the research object, the orthogonal experimental method design was employed to combine the parameters of the spoiler installation position. Then the wind energy utilization coefficient and the flow field structure of vertical-axis wind turbines were studied through numerical calculation, and the flow control mechanism of the spoiler and its effect on the aerodynamic performance of vertical-axis wind turbines were analyzed. The results show that the distance between the spoiler and the trailing edge of the blade is the main factor affecting the aerodynamic performance of vertical-axis wind turbines. By increasing the pressure difference between the suction and pressure surfaces of the blades, spoilers contribute to a higher aerodynamic performance of vertical-axis wind turbines. Additionally, the performance improvement effect on vertical-axis wind turbines is more significant at medium and low blade tip speed ratios. When the tip speed ratio is 1.8, the power coefficient of vertical axis wind turbines with spoilers is 25.3% higher than that of the original wind turbine. [ABSTRACT FROM AUTHOR]

This study investigates the aerodynamic performance and flow dynamics of an H-type Darrieus vertical axis wind turbine (VAWT) using combined numerical and experimental methods. The analysis examines the effects of operational parameters, such as rotor solidity and pitch angle, on aerodynamic loads and flow characteristics, using a 2-D URANS simulation with the Transition SST model to capture transient effects. Validation was conducted in a low-turbulence wind tunnel to observe the impact of variable flow conditions. The LineAverage method for determining the angle of attack demonstrated strong correlations between rotor configuration and load variations, particularly highlighting the influence of blade number and pitch angle on aerodynamic efficiency. This research supports optimization strategies for Darrieus VAWTs in urban environments, where turbulent, low-speed conditions challenge conventional wind turbine designs. [ABSTRACT FROM AUTHOR]

Plain flaps (PFs) significantly increase camber, enhancing lift and aerodynamic performance when deployed. In Darrieus Vertical Axis Wind Turbines (VAWTs), which perform efficiently in low-speed, turbulent wind conditions, structural modifications like PFs can improve efficiency. This study explores plain flaps with 10-20-degree deflections at different chord lengths to enhance the NACA 2412 aerofoil's performance. Using Unsteady Reynolds-Averaged Navier-Stokes (URANS) equations and the Shear Stress Transport (SST) k-ω turbulence model, simulations were conducted across high (Re ≈ 2.71 × 105), medium (Re ≈ 1.35 × 105), and low (Re ≈ 5.4 × 104) Reynolds numbers (Re). The 0.7–10 and 0.8–10 configurations significantly improved torque and Cp. At a Tip Speed Ratio (TSR) of 2.5, the 0.8–10 configuration increased the Cp by 19.51% over the flapless NACA 2412 without PF. The 0.7–10 configuration achieved the highest Cp across all TSRs, while a three-blade setup improved Cp by 43% compared to four- and five-blade configurations. The modified blades demonstrated consistent torque gains across all Re, proving the effectiveness of blade shape modifications in enhancing VAWT efficiency, particularly under fluctuating wind conditions, indicating the potential of PF-modified blades in improving small-scale wind turbine performance in varied urban environments. [ABSTRACT FROM AUTHOR]

The advantages of vertical axis wind turbines (VAWTs) have increasingly been recognized as effective turbomachines. Nonetheless, significant challenges remain regarding their efficiency and operational range. One promising approach to enhance their aerodynamic performance is the integration of vortex cavities, which can contribute to improved operational efficiency. This study utilizes computational fluid dynamics (CFD) to analyze the placement of vortex cavities systematically. The research investigates different configurations, such as suction side layout (SSL) and pressure side layout within single, double, triple, and quadruple arrangements to forecast their effect on H-type Darrieus VAWT aerodynamic performance. The findings show that the optimal configuration, with a concentration of 0.2 and 0.8 C in SSL, led to a 25% increase in power coefficient ( C p ) at the tip speed ratio (TSR) of 3.3. Conversely, the suboptimal configuration, with a concentration of 0.2 and 0.4 C in SSL, resulted in a substantial 54% decrease in C p at the same TSR due to issues with flow separation and lack of flow attachment after the vortex cavity. To optimize efficiency within the high-TSR range, a double, top, and bottom deflector configuration has been developed. Findings indicate that incorporating the double deflector has broadened the rotor's operational range from TSR 3.5 to 4.2 and concurrently elevated the rotor efficiency to 86%. [ABSTRACT FROM AUTHOR]

To investigate the effect of structural parameters on the aerodynamic characteristics of a Straight-Bladed Vertical Axis Wind Turbine (SB-VAWT), a 4-bladed SB-VAWT without an intermediate support shaft was designed to allow flexibility in changing structural parameters. Wind tunnel tests were conducted to measure the rotational speed, total lift, drag and torque of the wind turbine with different structural parameters at varying wind speeds. Based on the experimental design and optimisation, the wind turbine achieved the highest rotational speed and optimal power generation when the blades were installed in the forward direction at an installation angle of 10°, an installation radius of 160 mm, and a length of 600 mm. Under these optimal conditions, the speed and power generation characteristics of the wind turbine were tested at different wind speeds These results provide valuable insights for the design and application of similar wind turbines. [ABSTRACT FROM AUTHOR]

Darrieus vertical axis wind turbines are an omnidirectional type of turbine. The major concern with this type of turbine is its low efficiency. The experimental study focuses on implementing a bioinspired design. Humpback Whale flippers are mimicked for a novel design of a swept curved blade with leading-edge tubercles. A NACA4412 thin cambered profile and NACA0022 thick symmetric airfoil profile are chosen for making turbine blades, and the study is performed in the subsonic wind tunnel at Reynolds numbers ranging from 15,000 to 70,000. To validate the accuracy and novelty of the model over the conventional model, performance parameters like torque and power coefficients are calculated to showcase valid improvement in performance. It is exciting to observe that curved blades with tubercle leading edge modification have shown better results. Among seven configurations of turbine blades, the model with a high amplitude to wavelength A/ γ ratio showed more promising results than the other configurations regarding efficiency. A maximum of 35% C P was obtained with the novel curved tubercle model with A/ γ = 0.5, significantly enhancing electrical output. [ABSTRACT FROM AUTHOR]

Vertical axis small-scale wind turbines are gaining popularity because of their capacity to generate electricity from a renewable source by using wind from all directions. In this study the performance of a commercial Savonius vertical axis micro wind turbine with a rated maximum output of 2200 W have been analyzed through the modeling and simulation environment TRNSYS by varying the served building while installed into 5 different Italian cities. In particular, three typical different building typologies (a single-family dwelling, a small district consisting of 5 single-family dwellings, as well as an office) have been considered and the corresponding electric demands have been developed via an innovative stochastic approach. The climatic conditions have been taken into account by means of detailed weather data files. The building-integrated wind turbine's performance has been contrasted with a reference scenario that corresponds to the same building but uses the central electric grid exclusively. The comparison has been carried out from an energy, environmental, and economic perspective. The findings of simulations indicate that using the wind turbine can cut down the amount of electricity purchased from the central electric grid up to 37.51%, the global equivalent carbon dioxide emissions up to 37.74% and the operating costs up to 85.93%, with a minimum simple pay-back period of 1.09 years. [ABSTRACT FROM AUTHOR]

The Savonius U type wind turbine is a vertical axis turbine that can operate at low wind speeds. In general, the performance of this turbine is influenced by several factors, one of which is the shape of the turbine blade. This research aims to test the design results of a 6 blade Savonius turbine with a blade length of 50 cm made from polyvinyl chloride (PVC) by varying the dimensions of the blade diameter. The variables that vary between blade length and blade diameter are D/L=0.10, D/L=0.13, D/L=0.18, and D/L=0.20. The aim of this research is to determine the effect of variations in the parameters above on turbine rotation and the electrical power produced in a direct current (DC) generator at each variation in wind speed. From the research results, it is known that the trend graph of the relationship between turbine rotation and wind speed has a linear correlation. In simple terms, this turbine can be applied to DC voltage loads such as lighting using light emitting diode (LED) lamps with a maximum power capacity of ± 16 watts, while the overall efficiency (OE) is 50.25%. [ABSTRACT FROM AUTHOR]

In the present situation and considering the dangers that affect human life and the environment, it is necessary to expand the use of renewable energy that is available in all geographical areas. Environmental pollution caused by urban life has attracted researchers' attention to the use of renewable energy such as vertical axis wind turbines (VAWTs) with the aim of urban application. Because of their unique features, these turbines can provide the electricity needed for the targets, but to date, less attention has been paid to their tower structure. A wind turbine tower is one of the main and costliest components of wind systems. In this paper, based on the standards of turbine design and its structure, an algorithm was presented to create more resistance and strength in the tower structure and control the tower's deflection caused by incoming loads. Different models of simple monopole towers, variable crosssection monopole towers, monopole towers with channel beam control, and monopole towers with lateral restraint in the case study of Iran were simulated. Results show that models with lateral restraint have the lowest deflection of about 3 to 5 cm and, in addition to passing all design standards, the members' stress ratio is allowed within the limit. [ABSTRACT FROM AUTHOR]

The Savonius wind turbine is perceived favorable for a small-scale application because it is simple, relatively inexpensive, insensitive to wind directions, and has a good self-starting ability. However, it has a low power coefficient caused by the negative torque from the returning blade. This study aimed to investigate the effect of valve addition on the semi-circular Savonius rotor's performance. The experiments for this study were conducted on an open jet wind tunnel, with the valve located near the rotation axis, blade center, and rotor tip. The valve opening area ratio used was 0.02, 0.04, and 0.06, with Reynolds numbers 73,000, 86,000, and 99,000. The results showed that rotors with a valve placed near the tip performed better than those at the blade center and near the rotation axis. The performance decreased with an increase in the valve opening area ratio. Furthermore, the performance-improvement magnitude decreased with an increase in the Reynolds number. The rotor with a single valve near the tip performed the highest at a Reynolds number of 73,000. It achieved a maximum power coefficient of 0.199 compared to 0.183 obtained by a conventional Savonius rotor. [ABSTRACT FROM AUTHOR]

This research focuses on analyzing the aerodynamic characteristics of residual air currents generated by vehicle movement and evaluating their feasibility for energy generation, then designing a vertical axis wind turbine. The parameters assessed include the characteristic velocity profile, the average and maximum velocities, disturbance lifetimes, as well as the frequency and probability of recurrence of these disturbances. Using the data, projections are made on the electrical energy amount that can be produced by a wind turbine operating under such wind conditions. Measurements were taken at four locations: three within Mexico City (CDMX) and one on the outskirts. The measurement station, consisting of a 2.35 m vertical tower equipped with eight vertically aligned thermos-resistive anemometers, is installed on medians less than 0.50 m from moving vehicles. The data from within CDMX show maximum wind velocities ranging from 6 to 8 m/s at ground level, while measurements on the outskirts record velocities of up to 19.5 m/s. A probabilistic analysis reveals that usable air currents could be present 58% of the time. Based on electrical production calculations, it is estimated that harnessing this residual energy could power approximately 4500 homes, considering the national cost per kWh and the average electricity consumption of a four-person household. [ABSTRACT FROM AUTHOR]

Copyright of Baghdad Science Journal is the property of Republic of Iraq Ministry of Higher Education & Scientific Research (MOHESR) and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Integrating wind turbines within urban environments, either as building-mounted units or standalone installations, represents a valuable step toward sustainable city development. Vertical axis wind turbines (VAWTs) are commonly favored in these settings due to their ability to handle turbulent winds; however, they generally exhibit lower energy conversion efficiency compared to horizontal axis wind turbines (HAWTs). Selecting optimal urban or suburban locations with favorable wind conditions opens the possibility of deploying HAWTs, leveraging their higher efficiency even at comparable wind speeds. This paper presents a methodology for designing highly efficient HAWTs for urban use, supported by computational fluid dynamics (CFD) analyses to produce power curves and evaluate the energy conversion efficiency of both bare and augmented turbine designs. Differing from prior studies, this work also incorporates a detailed economic analysis, examining how reductions in the Levelized Cost of Energy (LCOE) enhance the cost-effectiveness of small-scale distributed wind systems. The findings offer insights into the technical and economic viability of small-scale HAWT configurations for distributed energy generation across diverse urban locations with varying wind profiles. [ABSTRACT FROM AUTHOR]

Vertical Axis Wind Turbines (VAWTs) offer several advantages over horizontal axis wind turbines (HAWTs), including quieter operation, ease of maintenance, and simplified construction. Surprisingly, despite the prevailing belief that HAWTs outperform VAWTs as individual units, VAWTs demonstrate higher power density when arranged in clusters. This phenomenon arises from positive wake interactions downstream of VAWTs, potentially enhancing the overall wind farm performances. In contrast, wake interactions negatively impact HAWT farms, reducing their efficiency. This paper extensively reviews the potential of VAWT clusters to increase energy output and reduce wind energy costs. A precise terminology is introduced to clarify ambiguous terms researchers use to quantify cluster parameters. While examining commonly studied and proposed VAWT cluster configurations, several aspects are discussed such as aerodynamic interactions, wake characteristics, structural dynamics, and performance metrics. Additionally, the current state-of-the-art and research gaps are critically described. The review also covers computational modeling, optimization techniques, advanced control strategies, machine learning applications, economic considerations, and the influence of terrain and application locations. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Hebei University of Science & Technology is the property of Hebei University of Science & Technology, Journal of Hebei University of Science & Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

This study introduces a novel approach to wind energy by investigating a novel Active Axis Wind Turbine design. The turbine is neither a horizontal nor vertical axis wind turbine but has an axis of operation that can actively change during operation. The design features a rotor with a single blade capable of dynamic pitch and tilt control during a single rotor rotation. This study examines the potential to balance the centrifugal and aerodynamic lift forces acting on the rotor blade assembly, significantly reducing blade, tower, foundation and infrastructure costs in larger-scale devices and decreasing the levelised cost of energy for wind energy. The design of a laboratory prototype rotor assembly is optimised by varying the masses and lengths in a lumped mass model to achieve equilibrium between centrifugal and lift forces acting on the turbine's rotor assembly. The method involves an investigation of the variation of blade pitch angle to provide a balance between centrifugal and aerodynamic forces, thereby facilitating the cost advantages and opening the opportunity to improve the turbine efficiency across a range of operation conditions. The implication of this study extends to different applications of wind turbines, both onshore and offshore, introducing insight into innovation for sustainable energy and cost-effective solutions. [ABSTRACT FROM AUTHOR]

As research into wave energy converters progresses and new developers enter the field, there arises a growing requirement for a standardized modelling approach. This article presents a novel design and dynamic emulation for a hybrid solar-wind-wave energy converter (SWWEC) which is the combination of three very well-known renewable energies: solar, wind and wave energy. Photovoltaic (PV) panels and vertical axis wind turbine (VAWT) are installed on top of the floating WEC that harness the energies from the sun and wind respectively. The SWWEC is designed with a point absorber capture system. An electrical motor is used to dynamically emulate the performance of the SWWEC under real world conditions to drive the DC generator. The present paper shows the importance and necessity of the required control schemes for the proper control of generator side converters which is present in the offshore marine substation and the most required grid connected onshore converters. The better switching signal generation for the converter control and generated harmonics elimination techniques are also presented in the paper. Outcomes of the present study are discussed and verified. [ABSTRACT FROM AUTHOR]

For aerodynamic performance improvement, a helical blade vertical axis wind turbine (VAWT) with a symmetric structure is proposed. Using NACA0018 as the base airfoil, three-dimensional numerical simulations of the symmetric helical blade VAWT and a helical blade VAWT are performed using the shear–stress transport k–ω model. The aims is to comprehensively explore the correlation and influence between their wind energy utilization coefficients, single-bladed transient moment coefficients, and flow field characteristics under different wind field conditions. Furthermore, the blade cross sections at positions of 0.3H, 0.5H, and 0.7H are symmetrized and subsequently numerically simulated in terms of both global and local symmetries. The symmetrical blades provide smooth and significant average moment coefficients under low tip speed ratios (TSRs) and similar average moment coefficients under high TSRs. The global symmetry helical blade VAWT (GS-helical blade VAWT) exhibited the best performance. Compared to the helical blade VAWT, the average value of the total moment coefficient afforded by the proposed GS-helical blade VAWT is 19.13% higher at TSR = 1 and similar at TSR > 1.9. In conclusion, the proposed symmetric helical blade VAWT exhibits improved aerodynamic performance and can be practically employed. [ABSTRACT FROM AUTHOR]

The aim of this study was to assess the accuracy of predicting the aerodynamic loads and investigate the aerodynamic wake characteristics of a vertical axis wind turbine (VAWT) rotor using a simplified two-dimensional numerical rotor model and an advanced numerical approach – the Scale Adaptive Simulation (SAS) coupled with the four-equation γ – Reθ turbulence model. The challenge for this approach lies in the operating conditions of the rotor, the blade pitch angles, and the very small geometric dimensions of the rotor. The rotor, with a diameter of 0.3 m, operates at a low tip speed ratio of 2.5 and an extremely low blade Reynolds number of approximately 22.000, whereas the pitch angles, β, are: -10, 0, and 10 degrees. Validation was conducted based on high-fidelity measurements obtained using the PIV technique at TU Delft. The obtained results of rotor loads and velocity profiles are surprisingly reliable for cases of β = 0° and β = –10°. However, the 2-D model is too imprecise to estimate both aerodynamic loads and velocity fields accurately. [ABSTRACT FROM AUTHOR]

The Darrieus vertical axis wind turbine (VAWT) is categorized as a lift-based turbomachine. It faces challenges in the low tip speed ratio (TSR) range and requires initial torque for the starting operation. Ongoing efforts are being made to enhance the turbine's self-starting capability. In this study, Computational Fluid Dynamics (CFD) simulations were utilized to tackle the identified challenge. The Unsteady Reynolds-Averaged Navier–Stokes (URANS) approach was employed, combined with the shear–stress transport (SST) k − ω turbulence model, to resolve fluid flow equations. The investigation focused on optimizing the placement of auxiliary blades by considering design parameters such as the pitch angle and horizontal and vertical distances. The goal was to increase the turbine efficiency and initial torque in the low-TSR range while minimizing efficiency loss at high-TSR ranges, which is the primary challenge of auxiliary blade installation. Implementing the auxiliary blade successfully extended the rotor's operational range, shifting the rotor operation's onset from TSR 1.4 to 0.7. The optimal configuration for installing the auxiliary blade involves a pitch angle of 0°, a horizontal ratio of 0.52, and a vertical ratio of 0.41. To address the ineffectiveness of auxiliary blades at high-TSRs, installing deflectors in various configurations was explored. Introducing a double deflector can significantly enhance the overall efficiency of the conventional Darrieus VAWT and the optimum rotor with the auxiliary blade by 47% and 73% at TSR = 2.5, respectively. [ABSTRACT FROM AUTHOR]

The operation of vertical axis wind turbines (VAWTs) to generate low-carbon electricity is growing in popularity. Their advantages over the widely used horizontal axis wind turbine (HAWT) include their low tip speed, which reduces noise, and their cost-effective installation and maintenance. A Farrah turbine equipped with 12 blades was designed to enhance performance and was recently the subject of experimental investigation. However, little research has been focused on turbine configurations with more than three blades. The objective of this study is to employ numerical methods to analyse the performance of the Farrah wind turbine and to validate the findings in comparison with experimental results. The investigated blade pitch angles included both positive and negative angles of 7, 15, 20 and 40 degrees. The k-ω SST model with the sliding mesh technique was used to perform simulations of a 14.4 million element unstructured mesh. Comparable trends of power output results in the experimental investigation were obtained and the assumptions of mechanical losses discussed. Wake recovery was determined at an approximate distance of nine times the turbine diameter. Two large complex quasi-symmetric vortical structures were observed between positive and negative blade pitch angles, located in the near wake region of the turbine and remaining present throughout its rotation. It is demonstrated that a number of recognised vortical structures are transferred towards the wake region, further contributing to its formation. Additional notable vortical formations are examined, along with a recirculation zone located in the turbine's core, which is described to exhibit quasi-symmetric behaviour between positive and negative rotations. [ABSTRACT FROM AUTHOR]

This article explores the potential of regeneration of power from unnatural wind sources with the help of vertical axis wind turbines (VAWT). Researchers are searching for urban as well as industrial wind sources, which can be useful as the natural wind source to obtain electrical energy and utilize it. The wind sources considered here are the exhaust of the cooling or ventilation fans used in buildings, industries, and other places. The Darrieus VAWT extracts wind power from the exhaust air and reduces the power consumption of the concerned electrical drives. These uncommon energy sources have an inherent capability to recover a significant amount of energy without polluting the environment with less payback period. Recovered energy can be suitably converted into electrical energy and may be fed back to the power grid without any pollution, thus minimizing the total energy consumption of the building and reducing the cost operations. A detailed study of experimental models with different types of assembly and turbine models is conducted here with power outputs and operational behaviors on the existing systems. Various parameters and factors for existing and new applications are in detail that show the system has no negative impact on regular operation. [ABSTRACT FROM AUTHOR]

Copyright of Karaelmas Science & Engineering Journal / Karaelmas Fen ve Mühendislik Dergisi is the property of Karaelmas Science & Engineering Journal and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Aiming at the problem that the wind energy utilization of vertical axis wind turbines is slightly lower than that of horizontal axis wind power,a new wind turbine based on Senegalese (Senegal) type wind turbine was proposed. Firstly, the curvature of the rotor blades was optimized using the Bessel curve function and modeled using the SOLIDWORKS software, resulting in four different curvature curves for the blades; Secondly, the parameters such as wind energy utilization, moment coefficient, and their pressure distribution and velocity distribution plots at different tip speed ratios were compared and analyzed using computational fluid dynamics (CFD) model, and their wake characteristics were also compared; Finally, an experimental platform was built to verify the rationality of the simulation. The results show that the optimized blade type effectively improves the wind energy utilization of the modified Senegal drag type vertical axis wind turbine, and the A4 type blade has a high wind energy utilization of 26.31%, which is about 36% higher than that of the A1 type wind turbine.The designed novel wind turbine structure has superior power generation performance, which provides some reference for program design in the field of vertical axis wind turbines.

The article contains a description of the design solutions proposed by the authors for a hybrid wind turbine bearing, in which the sliding part takes over the load to the turbine shaft after reaching the shaft rotation speed, ensuring hydrodynamic lubrication of the plain bearing and relieving the rolling bearing. This allows for low starting resistance of the power plant and ensures quiet operation during use. Two conceptual solutions of a hybrid bearing were presented, differing in the shape of the plain bearing journal. A mechanism for automatic switching of the load between a rolling and a plain bearing was developed. A solid simulation model of this mechanism was built in the Autodesk Inventor—Dynamic Simulation software Inventor Professional 2023 environment, and its operation was simulated. The results confirmed the usefulness of using this design in shaft-bearing systems of wind turbines with a vertical axis of rotation. Based on the simulation, the speed at which the thrust roller bearing will be released was determined. Technical parameters of a plain bearing with a spherical journal shape were calculated. The height of the lubrication gap and the shaft rotational speed at which the bearing load capacity index reaches a critical value were determined. [ABSTRACT FROM AUTHOR]

Micro wind power generation through vertical axis wind turbines for low wind velocity in the department of Santander, Colombia, is viable due to the physical characteristics of the region. However, there are crucial factors for the development of a turbine for the region such as turbine typology, robustness, aspect ratios, etc. For this reason, it is a good practice to perform simulations through computational fluid dynamics (CFD) to predict the performance of the turbine in operation. In this context, an analysis of six configurations of a Darrieus-type VAWT turbine with the asymmetric profile DU06W200 and straight blades, which were obtained by an algorithm considering the factors mentioned above was carried out. The height-diameter ratios to be analyzed were 0.25 (with chord lengths of 0.117 and 0.173 m), 0.4 (with chord lengths of 0.0929 and 0.137 m) and 1 (with chord lengths of 0.0587 and 0.0864 m). It can be concluded that with a ratio of 0.25 and a rope length of 0.173 m, it is possible to obtain an average Power Coefficient of 0.31, which is an outstanding value due to the low wind velocity of the region of interest. [ABSTRACT FROM AUTHOR]

This study experimentally investigates the impact of a pair of vertical-axis wind turbines at the leading corners of a tall building on its aerodynamic characteristics. These wind turbines have the potential to serve dual purposes: harnessing wind energy under normal wind conditions and mitigating wind loading of the building under strong wind conditions. The wind tunnel testing results in this study indicate when the tip speed ratio of the turbines is 0.34, with the wind turbines rotating toward downstream, the standard deviation of lift coefficient of the building decreases by 30.9%. Meanwhile, the mean pressure coefficient and the standard deviation of pressure coefficient on both the side face and leeward face of the building also exhibit a certain degree of reduction. The peak value of the power spectral density of lift coefficient of the building is also significantly decreased. This study clearly demonstrates that the wind turbines at the leading corners of tall buildings have the potential to effectively reduce wind loading of the buildings. [ABSTRACT FROM AUTHOR]

In this study, computational fluid dynamic (CFD) simulation of a vertical axis wind turbine (VAWT) geometry based on the Unsteady Reynolds–Averaged Navier–Stokes equations was investigated. In addition, the relationship between the geometric parameters of the VAWT and the two response variables, that is, moment and lift force, was determined using response surface methodology (RSM). Then, the Non‐Dominated Sorting Genetic Algorithm (NSGA‐II) was used to solve the multi‐objective optimization problem. The results obtained from the RSM showed that the lift force of the turbine is more sensitive to the change in the blade chord length, and the output moment of the turbine is more sensitive to the change in the rotor radius. Using the NSGA‐II multi‐objective optimization algorithm and the Technique for Order of Preference by Similarity to Ideal Solution (TOPSIS) method, it was determined that among the optimal values of the independent variable, the most optimal response occurs in blade chord length = 0.18 m, rotor radius = 0.4 m, blade pitch angle = −3.27° and number of blades = 4. In these optimal values of the independent variables, the values of the dependent variables, which included the turbine's moment and the blades' lift force, were obtained as 9.58 N m and 57.89 N, respectively. [ABSTRACT FROM AUTHOR]

There is a growing demand to improve the performance of vertical axis wind turbines to facilitate their commercialization for application in urban areas. This study utilizes a 3D numerical analysis to examine the influence of different vortices generated on turbine efficiency with straight and J‐type blades. The numerical simulation of this study employs the Reynolds‐Averaged Navier–Stokes equations and ‎sliding ‎mesh techniques ‎to more accurately model the rotational motion of blades about the turbine axis in relation to the ‎wind. Comparing the output ‎torque and the flow field at different span‐wise sections, the J‐type blades achieve better ‎performance at mid‐spans where the effect of stall vortices is dominant. Conversely, the lower ‎performance of J‐type blades is seen at tip spans due to stronger tip vortices. Investigations also ‎reveal the criticality of the downwind region on the overall performance at high tip speed ratios. It is observed that by ‎increasing the height, the tip vortices are limited to the tip sections, and stall vortices expand further ‎along the blade. At TSR = 1, the improvement by J‐type blades rises from 10% at a height of 0.8 m to 44% ‎at 3 m. The growth in height at lower wind speeds becomes more beneficial. Compared to the straight blades, the self‐starting ‎generated torque by J‐type blades for heights of 0.8, 1.2, and 1.6 m, are improved by 15.6%, ‎‎26.9%, and 34.7%, respectively. Overall, it is concluded that by increasing the blade height, the superiority ‎of the J‐type blade becomes more noticeable as the blade mainly contributes to suppressing the stall ‎vortices effect where the tip vortices effect is not presented. ‎ [ABSTRACT FROM AUTHOR]

A 2-D Lattice Boltzmann Method, designed to ensure stability at high Reynolds numbers, is combined with an Actuator Line Model to compute the loads on a two-bladed vertical axis wind turbine. Tests on the kernel size at a high mesh resolution reveal that a size equal to half of the full chord length yields the most accurate results. The aerodynamic load solution is validated against a fully resolved Scale-Adaptive Simulation (SAS) output, demonstrating high correlation, and enabling an assessment of near wake and downstream effects. The model's adaptability to various rotor operating conditions is confirmed through tests at high and low tip-speed ratios. Additionally, a Biot–Savart-based Vortex Model (VM) is employed for further comparison, showing good agreement with the Lattice Boltzmann output. The results indicate that the Highly Stable Lattice Boltzmann Method integrated with the Actuator Line Model enhances the accuracy of flow field resolution and effectively captures complex aerodynamic phenomena, making it a valuable tool for simulating vertical axis wind turbines. [ABSTRACT FROM AUTHOR]

The aim of this study was to improve the performances of three-bladed vertical-axis wind turbines with gap distance. For this purpose, turbine design conditions such as a gap ratio between the blades and the addition of blades were changed to provide performance increase, and an aerodynamic performance-enhancing performance setup placed in front of the vertical-axis wind turbine was also used. Therefore, in this study, the effects of gap distance and blade addition on wind turbine performance were investigated, especially by keeping the aspect ratio of the vertical-axis wind turbine constant. The investigation of the effects of turbine design parameters, such as the gap distance and additional blade number, on turbine performance was carried out using the ANSYS Fluent program with a numerical analysis method validated with experimental data. The turbine gap ratio, at which the maximum torque coefficient of a three-bladed vertical-axis wind turbine is obtained, was determined to be 40% without performance setup and 30% with performance setup. It was determined that the average torque coefficient value obtained from the turbine with the addition of turbine blades and with the performance setup increased by approximately 66% compared to the torque coefficient value obtained from the three-bladed turbine without the performance setup. It was also determined that the maximum power coefficient obtained from the vertical-axis wind turbine with optimum turbine design parameters with the performance setup increased by approximately 46% compared to the maximum power coefficient obtained from the version of the turbine without the performance setup. [ABSTRACT FROM AUTHOR]

The demand for clean and sustainable energy has led to the exploration of innovative technologies for renewable energy generation. The Savonius turbine has emerged as a promising solution for harnessing wind energy in urban environments due to its unique design, simplicity, structural stability, and ability to capture wind energy from any direction. However, the efficiency of Savonius turbines poses a challenge that affects their overall performance. Extensive research efforts have been dedicated to enhancing their efficiency and optimizing their performance in urban settings. For instance, an axisymmetric omnidirectional deflector (AOD) was introduced to improve performance in all wind directions. Despite these advancements, the effect of wind incident angles on Savonius turbine performance has not been thoroughly investigated. This study aims to fill this knowledge gap by examining the performance of standard Savonius configurations (STD) compared to the basic configuration of the deflector (AOD1) and to the optimized one (AOD2) under different wind incident angles and wind speeds. One key finding was the consistent superior performance of this AOD2 configuration across all incident angles and wind speeds. It consistently outperformed the other configurations, demonstrating its potential as an optimized configuration for wind turbine applications. For instance, at an incident angle of 0°, the power coefficient of the configuration of AOD2 was 61% more than the STD configuration. This ratio rose to 88% at an incident angle of 20° and 125% at an incident angle of 40°. [ABSTRACT FROM AUTHOR]

Wind turbines can freeze due to exposure to cold air. Ice formation on the rotor blades of a wind turbine reduces their performance. In the present work, the effects of ice formation on rotor blades of straight-blade vertical-axis wind turbines (SBVAWT) with a three-blade rotor and a NACA 0021 airfoil are numerically evaluated under two-dimensional transient settings by solving the continuity, momentum and turbulence equations become in ANSYS FLUENT. Grid and time step independence was investigated. For validation, the numerical model was compared with experimental data. An experimental ice model from the literature was then used to numerically simulate the iced rotor in twodimensional transition settings. The numerical simulation of the icy rotor was compared with an ice-free rotor. It was found that ice formation on the rotor blades changed the velocity and pressure fields around the rotor blades at angles of 180-360°, changing the streamlines and increasing the vortices. Furthermore, the maximum and minimum reductions in moment coefficient during blade icing occurred at angles of 225-315° and 45-135°, respectively. Due to ice formation on the rotor blades, the power coefficient of the rotor blades at angles 180-360° decreased drastically, and the power coefficient of the iced rotor was smaller than that of an ice-free rotor. It was concluded that ice formation on the blades of the SBVAWT reduced the average power coefficient of the blades and rotor power coefficient by 94.2% and 95%, respectively. [ABSTRACT FROM AUTHOR]

Omnidirectionality and simple design make VAWTs more attractive compared to HAWTs in highly turbulent and harsh operational environments including low wind speed conditions where this technology shines more. However, the performance of VAWTs is lacking compared to HAWTs due to low turbine efficiency at downstream caused by large wake vortices generated by advancing blades in the upstream position. Introducing variable design methods on VAWT provides better adaptability to the various oncoming wind conditions. This paper presents state-of-the-art variable methods for performance enhancement of VAWTs to provide better direction for the wind industry. The variable VAWT design can increase the lift and torque, especially at the downstream regions by managing the blade-to-wake interaction and blade angle of attack (AoA) well, hence contributing to the performance enhancement of VAWTs. In addition, the self-starting capabilities have also been found to improve by employing variable methods with a better angle of attack on the turbine blades. Nevertheless, the complexity of varying mechanisms and structural rigidity are the main challenges in adopting this idea. Yet, it possesses great potential to develop higher-efficiency VAWT systems that can operate in a wide range of wind speeds. [ABSTRACT FROM AUTHOR]

Vertical axis wind turbine (VAWT) has a rotating axis perpendicular to the wind direction. This type of wind turbine that is suitable for urban environments has low wind direction dependency and noise. In this research, a novel surrogated approach for optimizing a VAWT is proposed, used, tested, and verified, which is not reported in literature. The proposed method consisted of 3D computational fluid dynamics (CFD) analysis of wind flow through the wind turbine with FLUENT software by solving the unsteady turbulent equations. However, 3D CFD analysis was time and cost consuming to obtain the output result (power coefficient) from input values (airfoil chord length, pitch angle, and tip speed ratio as turbine design variables). Thus, artificial neural network (ANN) was applied to obtain weight functions to correlate FLUENT software inputs and outputs after learning process. Finally, genetic algorithm was used for maximizing the turbine power coefficient considering three defined design variables. The optimum value of power coefficient was improved to 0.244, and the optimum values of design variables for blade chord length, blade pitch angle, and blade tip speed ratio were 0.218, −0.453, and 1.24, respectively. This novel surrogated method reduced the computational time and cost of VAWT optimizing considerably. [ABSTRACT FROM AUTHOR]

Energy access is crucial for rural development in developing countries, as electrification drives economic growth, creates employment opportunities, and enhances the quality of life for rural communities. This study aims to determine the feasibility of powering a remote community with a hybrid energy system (HRS) combining solar photovoltaic, wind, and biogas to generate electricity and meet the energy needs of the rural area. West Waru Village was selected as the case study area due to its abundance of renewable energy sources. The HOMER tool was employed to model and optimize the HRS, providing a detailed analysis of its technical, economic, and environmental aspects. Furthermore, the study's findings were analyzed through a sensitivity analysis, considering uncertainty factors such as village load consumption, solar radiation, wind speed, and biomass availability. The best configuration for an on-grid scheme included a 2,284 kW photovoltaic (PV) system, 388 unit vertical axis wind turbine (VAWT), and a 500 kW biogas generator, resulting in a net present cost (NPC) of $8,506,090, a cost of energy (COE) of $0.054/kWh, and a payback period of 5.79 years. This configuration also reduced carbon dioxide (CO2) emissions by 67.2% compared to grid electricity. The optimal configuration for an off-grid scheme consisted of a 5,491 kW PV system, 954 VAWT, a 500 kW biogas generator, and 4,850 batteries, with an NPC of $20,162,390 and a COE of $0.1601/kWh, reducing CO2 emissions by 99.993%. These findings can serve as a baseline for the government to develop renewable energy systems in West Waru. [ABSTRACT FROM AUTHOR]

This study provides a numerical investigation about J‐shaped straight‐bladed Darrieus vertical axis wind turbines equipped with outboard, inboard, and two‐sided Gurney flap (GF). The performance of the turbines is examined for different GF heights and tip speed ratios (TSRs). The aerodynamic analysis is carried out using power curves, vorticity field, and pressure field surrounding the wind turbine. The results indicate that employing the inboard GF effectively enhances the turbine's performance by harnessing the drag force in the desired direction and postponing the flow separation up to 14° of azimuth angle. The inboard GF with a height of 0.75% chord length exhibits the best performance among the GFs, showing an increase in output power at higher TSRs up to 12.35%. Conversely, the use of outboard and two‐sided GFs of any height cannot improve the turbine efficiency. [ABSTRACT FROM AUTHOR]

Blade pitch angle regulation is an effective approach to enhance the performance of H-type Darrieus Vertical Axis Wind Turbines (VAWTs). Improving the blade interaction with the wind for this type of rotor is a challenging task, especially in unsteady wind conditions. This paper presents a novel hybrid approach that integrates fixed and variable blade pitch angle regulation techniques, aiming to enhance the wind turbine efficiency across various operational stages and wind speeds. The proposed blade pitch angle regulation method targets a less complicated, mechanically feasible, and cost-effective pitching technique. This study uses the Double Multiple Streamtube (DMST) model to analyze the aerodynamic performance and calculate the power output generated at different pitch angles. MATLAB Simulink was utilized to implement the DMST model, and experimental validation was conducted to confirm the results. The findings indicate that the blade pitch angle regulation has significantly enhanced the self-starting ability of H-type Darrieus VAWT by 80%. Additionally, the maximum rotational speed and power coefficient are achieved at a zero pitch angle. Furthermore, regulating the blade pitch angle allows for the effective control of excessive rotational speeds during high wind conditions. [ABSTRACT FROM AUTHOR]

Controlling wind flow on vertical axis wind turbine blades is an effective technique for enhancing their performance. Modern equipment such as plasma actuators have gained significant attention for their ability to control, and improve the flow behavior in wind turbines. Previous studies have primarily focused on investigating plasma actuators with constant force. In this study, plasma actuators with varying forces over time were applied to the turbine blades. An unsteady 2D model was used to analyze the wind turbine. The sliding mesh model was employed to simulate rotor rotation, and the SST k - ω model was utilized for turbulence modeling. Initially, the performance of the clean turbine was examined. In the next step, the plasma actuators with different force waveforms were applied to the wind turbine blades, including constant, sine, cosine, positive ramp, negative ramp, pulse in the first half-cycle, and pulse in the last half-cycle waveforms. The results indicated that the cosine, and sinusoidal waveforms, led to the greatest improvement with 37.28% and 35.59% increase in the net energy produced by the turbine, respectively, compared to the baseline case. [ABSTRACT FROM AUTHOR]

To achieve a better aerodynamic performance of wind turbines, the selection of a proper airfoil plays a crucial role. Generally, aviation airfoils (such as the NACA series) were widely used in the design of wind turbine blades due to their aerodynamic characteristics. However, several studies have shown that there are a number of defects in the application of aviation airfoils for blade design, such as poor stall characteristics or incompatible performance at different Reynolds numbers. The aerodynamic performance and lift force of newly developed airfoils inspired by cetaceans, birds, and insects were numerically investigated by CFD in the range of Reynolds number of 1.2 × 105 to 1.7 × 105 and a range of angles of attack (from 0° to 25°). ANSYS Fluent and the Shear Stress Transport (SST) k-ω turbulence models were selected to analyse the pressure and velocity distributions around the airfoils. In addition, the aerodynamic efficiency was calculated for all different cases. For verification and comparison, DU 06-W-200 airfoil was also simulated under the same operating conditions. Results revealed that several of these new bio-inspired designs can increase the aerodynamic performance of the DU 06-W-200 airfoil by up to 24.7%, with the bird-inspired airfoils presenting the best performance among all designs, and the best options for the design of vertical axis wind turbine (VAWT) blades. [ABSTRACT FROM AUTHOR]

A novel optimization method is developed for the design of an anti-icing blunt trailing-edge wind wheel of H-type vertical axis wind turbine (VAWT) based on the quasi-steady-state icing. The parametric expression of the airfoil is given using the mean camber and thickness functions, the blunt trailing-edge is constructed by the rotation and zoom of coordinates, and then through the aerodynamic design theory, the geometry control equations of the blunt trailing-edge wind wheel are established. The icing process using Solution and Icing modules is repeated at equal interval azimuths to obtain the ice on the wind wheel per revolution. The optimization model is solved using particle swarm optimization (PSO) algorithm integrated with computational fluid dynamics (CFD) method to maximize the wind energy utilization in both ice-free and icing conditions. Significant improvements are realized for flow and aerodynamic characteristics, confirming that the optimization method provides important guidance for an anti-icing design of VAWT blades. [ABSTRACT FROM AUTHOR]

Vertical axis wind turbines (VAWTs) have garnered significant attention due to their omnidirectionality, low noise, suitability for turbulent conditions, and high efficiency in offshore cluster deployments. VAWTs are more sensitive to dynamic stall, which can lead to reduced performance and reliability. Selecting appropriate blade airfoils can enhance both performance and reliability. This study employs a parametric method to design 12 input parameters for controlling the blade airfoil, with the average power coefficient of a single vertical wind turbine blade and the coefficient of variation of the main shaft as output parameters. The Non-dominated Sorting Genetic Algorithm II multi-objective genetic algorithm is used for blade airfoil optimization, selecting the two best-performing airfoils from the Pareto front. The average power coefficient of a single blade increased by 8.6% and 4.3%, respectively, while the coefficient of variation decreased by up to 6.7% and 5.3%. The analysis of the blades at different azimuth angles indicates that optimized blades can suppress flow separation at high angles of attack, enable faster wake recovery, and reduce energy loss. [ABSTRACT FROM AUTHOR]

Advances in non‐conventional energy technologies and increasing fossil fuel prices along with environmental concerns have made hybrid renewable energy systems important. In view of this scenario, solar panel mounted on a vertical axis wind turbine (called as solar‐wind tower) can be utilized to produce more electric energy than individual one. This solar‐wind tower will be located in the space available between two opposite roads of expressways/highways. Solar‐wind tower located in such a manner that the air velocity produced from driving vehicles on both sides of the road is adequate to cut the turbine blades which will produce unidirectional torque. A battery energy storage system (BESS) stores the power produced by the solar‐wind tower so that it can subsequently be used for local loads and electric vehicle charging stations (EVCS) and remaining energy can be supplied to the grid. In this work, a hybrid system composed of wind and solar is designed and modelled in Simulink (MATLAB) and tested on real data of wind speed and validated by Opal‐RT simulator. From the simulation result, it is estimated that total electrical power output of a single solar‐wind tower is around 15 to 20 kWh in a day under the assumed conditions. [ABSTRACT FROM AUTHOR]