Savonius Vertical Axis Wind Turbine Research Articles

Design of Savonius Vertical Axis Wind Turbine for Vehicle

The use of cellular phones is increasing in society, but due to the limited battery capacity of cell phones, it is necessary to charge the battery when travelling in the long distances. The Savonius type wind turbine has a potential as an energy source harvesting the wind energy flowing around the car. However, due to the available space on the car, careful design of Savonius vertical axis wind turbine for vehicle is necessary. The research is conducted numerically using MATLAB software. The wind speed, Reynolds number, and electric power output are numerically simulated to obtain the swept area design. Innovative PLA material in the design is also investigated by simulating the effect of mass inertia moment to the design. This design of Savonius vertical axis wind turbine for vehicle is expected to charge maximum four cell phone batteries with the total electrical output of 60 W. The optimum swept area design of Savonius vertical axis wind turbine for vehicle is 0.150 m 2 using 3 fins, PLA filament material, with an overlap of 5.3 cm, and a diameter for each blade 22 cm according to the overlap ratio used of 0.242. This Savonius vertical axis wind turbine design is feasible as an energy source for vehicle owing to its compact design, innovative material used in the design, and providing the electric power demand in the vehicle.

A Computational Fluid Dynamics Study of an Integrating Savonius-Darrieus Vertical Axis Wind Turbine

To combine the advantages of performance of both Savonius and Darrieus wind turbines, this paper aims to study computationally a novel design configuration of a Vertical Axis Wind Turbine (VAWT). The new design would help cover a broad range of performance parameters between both types of wind turbines as well as overcome drawbacks of the Savonius type at higher rotational speed. The proposed design is to integrate both of Savonius and straight blade Darrieus wind turbines in a single VAWT design configuration. In this design, the turbine rotor consists of a number of similar NACA0015 airfoil blades set in a particular arrangement. By regulating individual angles of rotor blades, the turbine would work as either Savonius or H-Darrieus VAWT. The turbine could also be set to work at different configurations between those for the Savonius and H-Darrieus ones. The computational results revealed that the performance of the proposed integrating wind turbine would be controlled and optimized to cover the operating range of both of Savonius and Darrieus wind turbines. Besides, the performance of Savonius VAWT would be modified when applying this design. When the proposed design is practically implemented, characteristics of both of Savonius and H-Darrieus based wind turbines would be found in a single design.

Performance improvement of a Savonius vertical axis wind turbine using a porous deflector

The present study proposed a novel porous deflector in front of the Savonius wind turbine to improve the performance. This new deflector was specifically proposed to minimize the severe effects of the complex wake zone created behind the conventional solid deflector that had not been investigated yet. This caused a deeper investigation into the effect of severe negative effects on the turbine performance to achieve an appropriate design configuration. Therefore, different configuration parameters were taken into account during the numerical process. The unsteady Reynolds-averaged Navier-Stokes equation in conjunction with the SST k-ω turbulence model was numerically solved. Comprehensive comparisons of torque, power, and flow structures between deflector configurations and the standard Savonius turbine were performed to illustrate the mechanism of how the porous deflector improved the turbine performance. Using a porous deflector caused the wind flow passed through the porous zone resulted in a breakdown of the wake zone behind the deflector. Thereby, the flow structures became more regular with fewer fluctuations. The results demonstrated that there is an appropriate porosity value to obtain the highest torque and power coefficients. The maximum value of the power coefficient increased by approximately 10% using the favorable configuration of porous deflector at a tip speed ratio of 1. The notable observation was that the appropriate configuration increased the static torque coefficient approximately 2 times in the rotation angles between 0° and 30° which proved the self-starting ability besides power coefficient enhancement.

Performance enhancement of twisted-bladed Savonius vertical axis wind turbines

It is important to determine the most optimal configuration of a Savonius vertical axis wind turbine that attains the best performance with a high self-starting ability. Thus, the effects of several design parameters including twist angle, overlap ratio, and endplates size ratio, along with the wind velocity on the performance of the Savonius wind turbine are investigated. Novel assessment methods based on flow field characteristics such as streamlines and pressure fields around the Savonius wind turbine are carried out. This is the first contribution to understand how geometrical variables influence the aerodynamic performance of the twisted Savonius rotor. Moreover, the variation of torque, power, thrust, and static torque coefficients are estimated. Thus, a three-dimensional, incompressible unsteady Reynolds-averaged Navier-Stokes model in conjunction with k-ω shear-stress transport turbulence model is developed. The model is numerically simulated and validated using the experimental and numerical data available in literature. Results indicate that the Savonius rotor with a twist angle of 45°, an overlapping ratio of zero, and endplates size ratio of 1.1 attains the highest net output power compared to other designs. It is found that at a wind velocity of 6 m/s, the Savonius rotor achieves a maximum power coefficient of 0.223, and with further increase of the wind velocity to 10 m/s, the power coefficient reaches 0.231. In addition, the current developed design has a positive static torque coefficient at all rotor angles, and consequently, it achieves a high self-starting ability. However, for the conventional (untwisted) design, the maximum attainable power coefficient was found to be 0.174 at an overlapping ratio of 0.15, and equal endplate size ratio. In addition, negative values of the static torque coefficient were observed at a specific range of rotor angles that prevent the self-starting ability. Accordingly, the new twisted rotor design not only enhances the power coefficient but the self-starting ability as well. The findings of the current results provide another direction for researchers and designers to utilize the twisted Savonius wind turbine.

Casing optimization of a Savonius wind turbine

In an attempt to enhance the performance of a Savonius Vertical Axis Wind Turbine (VAWT), case sizing optimization was performed utilizing Computational Fluid Dynamics (CFD) technique. A 2D parametric optimization process was employed to optimize a number of assigned design parameters of the casing’s geometry. The configuration of El-Askary et al. (2015) was adopted as a starting baseline for the optimization. The turbine with the optimized casing provided a superior performance compared to a caseless one, specifically at low Tip Speed Ratios (TSRs). A maximum increase of 42.5% in the power coefficient (Cp) was attained at a tip speed ratio of 0.59. The obtained results demonstrate the nonexistence of a universal optimal casing shape that maintains peak turbine performance at all tip speed ratios. However, optimized casing dimensions follow a clear trend that is closely related to TSR values.

Simulation studies to analyze the static mechanical properties of helical Savonius vertical axis wind turbine blade

The focus of this study is to analyze the static mechanical properties of the helical Savonius vertical axis wind turbine blade. Commercial finite element code ANSYS is used to perform the static structural analysis. The helical Savonius wind turbine blade is tested by force varying from 15 N to 25 N representing the wind conditions ranging from 5 m/s to 11 m/s. The properties namely, maximum principal stress, equivalent (von-misses) stress, shear stress, maximum shear stress, equivalent elastic strain, and total deformation are analysed. The various static mechanical properties are observed to be the maximum for wind load of 15 N. The outer edges of the helical Savonius vertical axis wind turbine blade is observed to have the maximum total deformation values and the prolonged use of the helical Savonius wind turbine blade will lead to damage along the outer edges of the turbine blade leading to failure of the wind turbine blade.

Numerical and Experimental Investigations on a Dimpled Savonius Vertical Axis Wind Turbine

This research deals with the design and fabrication of novel designs as a mean to harness wind energy using a ‘Savonius’ Turbine. It is generally employed to harvest the low to very low wind speed potentials. They can particularly be of high use in the regions where the wind speeds are not high enough for installing conventional horizontal axis wind turbines. The paper introduces a novel concept of testing a Savonius wind turbine with dimple structures on its blades and investigating its effect on the turbine’s efficiency. The study also deals with the experimental validation of the effect of using a converging ducted structure with a single stage and double stage configurations of Savonius wind turbine, apart from comparing the turbine’s performance with and without endplates. The results of the study proves that power coefficient increases with the addition of dimple structures on the blades and it can be further augmented by using a ducted structure with the Savonius turbine.

Utilization of guide vanes to concentrate flows to the blade and block vortex to improve the power factor of savonius wind turbine

Simple design Savonius vertical-axis wind turbine can generate energy at low wind speed from any direction. However, its large static torque has a low power factor. Therefore, an innovation was made by providing 16 guide vanes around the shaft outside the blade with the angle is about 45° to a radial line. The specialty of guide vanes is that , they are able to concentrate the wind flow toward the turbine blade from any direction. The fluid motion around the turbine blade that produces torque on the turbine shaft was analyzed utilizing the Computational Fluid Dynamics (CFD) simulation and then verified by tracking actual fluid motion strings of threads attached on each side of the turbine blade. The result shows that without guide vanes the wind flow around the turbine blade generates vortex on the blade and Karman vortex at the downstream. These vortexes descend effectively kinetic energy in the wind flow so that the mechanical energy on the turbine shaft becomes small. At a certain blade position, the vortex becomes stronger and the fluid separation from the blade surface becomes thicker. The stronger vortex tends to descend stronger fluid kinetic energy while the thicker separation tends to reduce the lift on the blade. Consequently, these two flow conditions tend to produce negative torque. Installing guide vanes around the blade, the wind flows are concentrated by the guide vanes to the turbine blade, which effectively reduces vortex around the blade and blocks large vortex outside the guide vanes downstream. Flow separation is suppressed by the concentrated flow producing larger lift. As a result, the power factor increases by 61.6 %. This huge increase in power factor is achieved when the wind speed is 5 m/s though a stable turbine rotation is achieved at a lower speed

Variation of energy utilization efficiency with respect to inlet wind speed for eight-blade modified Savonius rotor by CFD approach

ABSTRACTThis study investigates the optimal wind utilization efficiencies of eight-blade modified Savonius vertical axis wind turbine as a function of blade width, blade installation, and rotor speed under various inlet wind speeds. All the simulations are designed based on the uniform test method and conducted by computational fluid dynamics (CFD) numerical calculation. Sliding mesh approach and k-ω SST turbulence modeling are employed in the processing. Results indicate that the optimal wind energy utilization efficiency and rotor speed increase almost linearly with the inlet wind speed for the modified eight-blade Savonius rotor with the diameter of 4 m in the range of wind speed from 6m/s to 10 m/s, while the changes of the optimal blade width and installation angle are non-monotonous.

Experimental studies on the effect of obstacle upstream of a Savonius wind turbine

The present studies investigate the performance of a small Savonius vertical axis wind turbine equipped with an upstream obstacle to guide the wind direction. The wind tunnel measurement was carried out in a test facility at the Mechanical Engineering Department, Institut Teknologi Sepuluh Nopember (ITS). The dynamic torque was measured using the brake dynamometer. Several variations of the obstacle orientations were investigated. Two different wind speeds of 2.48 m/s and 7.45 m/s were considered, that correspond to the Reynolds numbers of 30,000 and 90,000, respectively, according to the rotor diameter. It is found from the studies that the mechanical torque and power generated by the rotor are strongly affected by the obstacle. On the other hand, the Reynolds number has no significant impact on the rotor performance.

Diseño experimental de Aerogenerador tipo Savonius

This project applies renewable energy technology, the calculation and design of an experimental Savonius vertical axis wind turbine is described. The objective is to acquire the necessary information for the construction and modeling of an experimental wind turbine. This prototype was constructed to use the movement of the air to generate electricity in a clean and non-contaminant way. The parts were assembled to make as much energy as its possible, those designs were calculated using the formulas of wind resource harnessing. Following this clean and non contaminant ideas, we recycled most of the materials used for the construction of this prototype. We calculated the rotative speed of the device according to the wind, we also calculated the electric energy that the device could generate with the wind. We studied the environment data such as wind speed, temperature for three weeks, where installed the experimental device it is going to be.

Numerical Investigation of the Savonius Vertical Axis Wind Turbine and Evaluation of the Effect of the Overlap Parameter in Both Horizontal and Vertical Directions on Its Performance

Exploiting wind energy, which is a complex process in urban areas, requires turbines suitable for unfavorable weather conditions, in order to trap the wind from different directions; Savonius turbines are suitable for these conditions. In this paper, the effect of overlap ratios and the position of blades on a vertical axis wind turbine is comprehensively investigated and analyzed. For this purpose, two positive and negative overlap situations are first defined along the X-axis and examined at the different tip speed ratios of the blade, while maintaining the size of the external diameter of the rotor, to find the optimum point; then, the same procedure is done along the Y-axis. The finite volume method is used to solve the computational fluid dynamics. Two-dimensional numerical simulations are performed using URANS equations and the sliding mesh method. The turbulence model employed is a realizable K-ε model. According to the values of the dynamic torque and power coefficient, while investigating horizontal and vertical overlaps along the X- and Y-axis, the blades with overlap ratios of HOLR = +0.15 and VOLR = +0.1 show better performances when compared to other corresponding overlaps. Accordingly, the average Cm and Cp improvements are 16% and 7.5%, respectively, compared to the base with a zero overlap ratio.

Aerodynamic Analysis of a Three-Bladed Pivoted Savonius Wind Turbine: Wind Tunnel Testing and Numerical Simulation

In this study, a three-bladed pivoted vertical axis Savonius wind turbine is subjected to numerical and experimental studies. The experiments are carried out in a subsonic open-jet type wind tunnel, where the instantaneous position of the opening/closing blades are also determined via high speed imaging. The effects of adding end plates and the rotor aspect ratio on the turbine torque and power coefficients are investigated experimentally. Results show that adding end plates greatly enhances the rotor aerodynamic performance, in terms of both the maximum power coefficient and also the working range of the turbine. Similar effects are also observed for the effects of increasing the aspect ratio. Comparing numerical results with the experimental data demonstrated that the numerical results are in a convincing agreement with the experimental data of a wind rotor with an aspect ratio of 2.0 equipped with end plates. Although there are several two-dimensional numerical simulations for the drag-based vertical axis wind turbines in the literature, the results of the current study suggests that two-dimensional numerical results are not comparable with the experimental data of the rotors with small aspect ratios, especially without end plates.

Influence of blade profiles on Savonius rotor performance: Numerical simulation and experimental validation

In this work, some notable blade profiles of drag-based vertical axis Savonius wind turbine rotor have been investigated both numerically and experimentally to judge their performances on a common platform. At the outset, 2D unsteady simulation is performed for semicircular, Benesh, modified Bach and elliptical profiles keeping the overall rotor diameter in each case to be constant. The simulation has been carried out using the Shear Stress Transport k-ω turbulence model with the help of the finite volume solver ANSYS Fluent. The torque and power coefficients, in each case, are estimated as a function of tip speed ratio. The total pressure, velocity magnitude, and turbulence intensity contours are obtained and analyzed. Finally, wind tunnel tests are conducted to validate the numerical results. From the numerical simulation, the maximum power coefficients for the semicircular, Benesh, modified Bach and elliptical profiles are found to be 0.272, 0.294, 0.304 and 0.34, respectively. However, the wind tunnel tests with the semicircular, Benesh, modified Bach and elliptical-bladed rotors demonstrated the maximum CP to be 0.158, 0.159, 0.162, and 0.19, respectively.

Performance Estimation of Modified Savonius Wind Turbine Blade Profile

Nowadays most wind turbines installed today are of large size, small wind turbines are also getting attention day by day because they can be installed easily and supply the electricity in standalone areas and for domestic use. The major challenges associated with small wind turbine are the noise from the wind turbine due to turbulence and power production. An effort has been made to modify the blade profile of the vertical axis Savonius wind turbine using an end plate. And the performance has been estimated. Like horizontal axis wind turbine airfoil shape has been given to the S type blade. The results are supported by validating it with the simulation results.

Parametric sizing optimization process of a casing for a Savonius Vertical Axis Wind Turbine

The aim of this work is to improve the performance of a Savonius Vertical Axis Wind Turbine (VAWT) by sizing a suitable rotor guide plates configuration, or what is called a turbine’s casing, using Computational Fluid Dynamics (CFD) technique. Starting from a proposed baseline casing design, a 2-D parametric optimization process was followed, where several design parameters pertaining to the casing’s geometry were assigned and optimized. Owing to the limitations of the 2-D numerical simulations, the optimized casing dimensions were extracted and used to carry out 3-D numerical investigations. The turbine with the optimized casing readily performed better than the caseless one, especially at lower Tip Speed Ratios (TSR). In addition, the obtained results showed that there exist no universal optimal values for the casing dimensions that maintain peak turbine performance at all TSRs. Thus, a clear trend relating all the optimized casing dimensions to the TSR was established.

Performance analysis of a savonius vertical axis wind turbine integrated with wind accelerating and guiding rotor house

Though Micro Wind Technology has several advantages but its expansion is very slow due to few significant limitations such as low efficiency of wind turbines and public concerns regarding safety in the turbine vicinity, noise and visual impact. To overcome the limitations of micro wind technology, a Rotor House (RH) for vertical axis wind turbine has been proposed in the literature. It has been claimed that the RH utilizes free stream wind parcel of the area nearly double than the swept area of rotor and amplify velocity magnitude in the rotor zone up to 1.52 times the value of free stream velocity. In the present study contribution of proposed RH in terms of increase in the performance of micro vertical axis wind turbine has been investigated experimentally. In this regard a conventional three bladed savonius rotor model and RH model with optimized design is manufactured and tested under laboratory conditions as well as in open air conditions (field testing). By creating venture effect, the RH accelerates wind flow in the rotor zone and concentrates the flow on the effective location of rotor blade located inside the structure. RH contributes to improve the power coefficient of rotor from 0.125 to 0.218.

CFD Study of Unsteady Flow Through Savonius Wind Turbine Clusters

The interaction between Savonius vertical axis wind turbine clusters installed in far or close proximity can devalue or enhance the output power of single Savonius vertical axis wind turbines. In this paper, the effect of spatial distribution is studied for the development of efficient Savonius vertical axis wind turbine farms. Numerical simulations are performed for a single Savonius wind turbine, sets of two rotating turbines in three different configurations (aligned, parallel and oblique configurations), and clusters of three rotating turbines, using five separation distances of 0.25D, 0.5D, 1D, 1.5D and 2D, making a total of twenty-two test scenarios. The commercial CFD software Fluent 15.0 is used for the numerical study. The torque and power coefficient results of single Savonius turbine are compared and validated against experimental and numerical data based on the literature review. The results showed that there was a combined effect related to the inter-turbine distance and the output power. This combined effect showed an efficient three Savonius turbine cluster having an average power coefficient 3 times higher than an isolated turbine. Best Savonius farm efficiency and high output power could be obtained by considering, at least, these two parameters.

Computational fluid dynamic analysis of roof-mounted vertical-axis wind turbine with diffuser shroud, flange, and vanes

Advances in wind power and tidal power have matured considerably to offer clean and sustainable energy alternatives. Nevertheless, distributed small-scale energy production from wind in urban areas has been disappointing because of very low efficiencies of the turbines. A novel wind turbine design — a seven-bladed Savonius vertical-axis wind turbine (VAWT) that is horizontally oriented inside a diffuser shroud and mounted on top of a building — has been shown to overcome the drawback of low efficiency. The objective this study was to analyze the performance of this novel wind turbine design for different wind directions and for different guide vanes placed at the entrance of the diffuser shroud. The flow field over the turbine and guide vanes was analyzed using computational fluid dynamics (CFD) on a 3D grid for multiple tip-speed ratios (TSRs). Four wind directions and three guide-vane angles were analyzed. The wind-direction analysis indicates that the power coefficient decreases to about half when the wind is oriented at 45° to the main axis of the turbine. The analysis of the guide vanes indicates a maximum power coefficient of 0.33 at a vane angle of 55°.

Performance of a Small-sized Savonious Blade with Wind Concentrator

<span>This paper presents the performance of a fabricated small-sized Savonious wind turbine with two blades. The design of Savonius vertical axis wind turbine (VAWT) was based on Malaysia wind speed condition. Meanwhile, the design of wind concentrator was based on the dimensions and the constant airflow of an air compressor. From the experimental testing in a laboratory, it was found that the proposed Savonious turbine has best performance when tested using wind concentrator. To conclude, airflow from air compressor can be increased when the proposed wind concentrator is used and hence increasing the proposed VAWT performance in terms of its angular speed (ω), tip speed ratio (TSR) and the generated electrical power (PE).</span>