Conventional Savonius Wind Turbine Research Articles

Performance Improvement of a Savonius Wind Turbine using Wavy Concave Blades

As the best replacement for fossil fuels, green energy resources have established their significance on a worldwide basis. The availability of wind energy makes it the best promising form of green energy. For transforming wind kinetic energy into mechanical energy at low wind speeds, the Savonius wind rotor is regarded as the best choice. The main goal of the current study is to improve the power coefficient (Cp) and torque coefficient (Ct) of the Conventional Savonius wind turbine (SWT) by modifying the inner surface of the blade using a wavy profile. The aerodynamic performance of the wavy turbine is then compared with the conventional turbine in terms of Cp and Ct. The study is conducted using numerical simulation with the assistance of the ANSYS software. The flow characteristics around the turbines are solved utilizing the SST k-ω turbulence model. The simulation outcomes confirmed that the Cp of the wavy rotor increased by about 14.5% at a tip speed ratio of λ= 0.4. Additionally, outcomes showed the peak Cp is 0.18 at λ=0.7 which is 12.5% greater than the conventional SWT

Examination of the Effect of Triangular Plate on the Performances of Reverse Rotating Dual Savonius Wind Turbines

In the present study, the performance of the Savonius wind turbine in designs with dual turbines rotating opposite to each other was examined. To improve the performance of the Savonius wind turbine in the dual turbine design, a triangular plate was placed in front of the turbines. The effects of the geometric parameters of this triangular plate which was placed on the turbine performance were studied. The numerical analyses performed were confirmed by the experimental data of a previous study in the literature. The performance values of Savonius wind turbines were analyzed by numerical analysis, the accuracy of which was proven by experimental data. ANSYS Fluent, a computational fluid dynamics (CFD) program, was used for the performance analysis. In the first stage, the maximum power coefficient (Cp) of the conventional Savonius wind turbine was obtained around 0.17. With the optimum geometric parameter studies, the maximum power coefficient of the Savonius wind turbine in the triangular plate dual turbine design was determined to be around 0.22. Thus, it was found that the power coefficient obtained by a single Savonius wind turbine in a triangular plate dual turbine design was around 30% higher compared to the power coefficient of the conventional Savonius wind turbine.

Numerical Investigation of a New Modified Savonius Wind Turbines

The classic Savonius semi-circular blade turbine has a relatively low power coefficient.The performance of a Savonius wind turbine depends on its geometrical parameters. Various blade profiles have been developed in the past years to improve the performance of this class of turbine. In this paper, a new blade shapes of Savonius wind turbine is investigated numerically by using the CFD method , by using transient conditions and set k omega turbulence model.The new blade has different concave and convex shape, which is a combination of the conventional and the elliptical blade. A comparative study of three blade profiles, semi-circular, elliptical and the composed blades have been performed.Flow structures around the rotor have also been analyzed. The results show that changing the blade shape has an effect on the performance efficiency of the Savonius turbine.The new modified and the elliptical blade exhibit higher performance compared to the conventional Savonius wind turbine. The new modified Savonius blade and the elliptical blade exhibit an improved performance compared to the conventional model in the order of 20.5% and 18.2% respectively at the tip speed ratio of 0.8.

Aeroacoustics behavioral study of Savonius wind turbine

Vertical Axis Wind Turbines (VAWTs) are appropriate for use in populated areas. If VAWTs were installed at residential areas, the generated aerodynamic noise can be harmful in a way or another. Therefore, in the present study, the aero-acoustics of the conventional Savonius Wind turbine was investigated using Computational Fluid Dynamics (CFD). Both the Unsteady Reynolds-averaged Navier-Stokes (URANS) equations and impermeable Ffowcs Wiliams and Hawkings (FW-H) equation were simultaneously solved. The effect of speed ratio was also studied. The results indicate that; the pressure is inversely proportional to the speed ratio. Additionally, the velocity has been increased due to the increase of the tip speed ratio. Finally, it has improved that for the majority of receivers, the overall sound level increases with increasing speed ratio.

Comparison of Various Blade Profiles in a Two-Blade Conventional Savonius Wind Turbine

Abstract Savonius turbines are one of the old and cost-effective turbines which extract the wind energy by the drag force. Nowadays, they use in urban areas to generate electricity due to their simple structure, ease of maintenance, and acceptable power output under a low wind speed. However, their efficiency is low and the improvement of their performance is necessary to increase the total power output. This paper compares four various blade profiles in a two-blade conventional Savonius wind turbine. The ratios of blade diameter to the blade depth of s/d = 0.3, 0.5, 0.7, and 1 are tested under different free-wind speeds of 3, 5, and 7 m/s and tip speed ratios (TSRs) in the range from 0.2 to 1.2. It is found that the profile of blades in a Savonius rotor plays a considerable role in power characteristics. Also, regardless of blades profile and free-wind speed, the maximum power coefficient develops in TSR = 0.8. In addition, increasing the free-wind speed enhances the rotor performance of all cases under consideration. Finally, it is revealed that the rotor with s/d = 0.5 provides maximum power coefficients in all free-wind speeds and TSR values among the rotors under consideration, whereas the rotor with s/d = 1 is the worth cases.

Experimental Studies of Performance Savonius Wind Turbine with Variation Layered Multiple Blade

The solution to various environmental problems now is the development of renewable energy. One of the renewable energy that was sociable to the environment and easily obtained is wind energy. Savonius wind turbines are proper to be applied in Indonesia which have low wind speeds, besides that Savonius also has many advantages over other wind turbines. In this paper experimental study is done a study on conventional Savonius wind turbine and modified Savonius wind turbine by added multiple layer 90°, 115°, 135° at positions 0° and 30°. The schematic supportive testing is done by blower fan. The wind speed used in testing with a range of 4.99 m/s to 7.27 m/s. The test results showed that the addition of multiple layers could be increased Savonius’s power coefficient to 17.6%. The maximum power coefficient obtained by Savonius turbine was 0.120 with variations multiple layer 90° at 0° position. So, the addition of multiple layer can be improved the performance of the Savonius wind turbine

A moment coefficient computational study of parametric drag-driven wind turbine at moderate tip speed ratios

ABSTRACT This paper presents the CFD numerical investigation of novel drag-driven wind turbine blade inspired by spiral optimisation algorithm (SPO) and cycloid curve. In this study, six hybrid spiral geometries were analysed via CFD simulation using FLUENT based on URANS and SST numerical model. The simulated results of six shapes were compared against simulated conventional Savonius wind turbine. In terms of moment coefficient, all the turbines were simulated under similar computational configuration. The turbines were studied at two moderate tip speed ratios, which are λ = 0.59 and λ = 0.94, under constant freestream velocity of 8 m/s. The result shows that design shape S-4 displayed higher moment coefficient than Savonius wind turbine with an improvement of 7.2% in moment coefficient at λ = 0.59. However, at λ = 0.94, the percentage of improvement in moment coefficient is only 4%. It is observed that reduction in blade height and modification of blade curve configuration improve the moment of the rotor. The sharp edge presented by the hybrid spiral shape induces higher pressure gradient than Savonius wind turbine on the convex side of the blade.

Simulation study of Savonius tandem blade wind turbine using an adjustable deflector

The conventional Savonius wind turbine has two inverted cylindrical blades, it can indeed receive fluid impulses from all horizontal directions and produce a greater drag force than other wind turbines. The weakness of Savonius is the resistance in one blade side. Efforts to improve that has been done is to add a blade that serves to increase the local velocity of fluid flow to resist the resistance which is termed Savonius tandem blade (STB). This research was conducted to further reduce the resistance value of one side STB with the addition of an adjustable deflector. The purpose of this study is to obtain information on changes in the torque of the STB wind turbine on variations in the deflector angle and stream velocity. The research method used is numerical simulation using CFD software. A two-dimensional view of the rotor model using deflector was considered. The deflector angle varies start from 15 degrees with an increase also every 15 degrees until the torque decreased. The CFD simulation show there is a significant increase in torque with the addition of a deflector. Maximum torque is not achieved at one deflector angle value but is also influenced by stream velocity. At higher stream velocity there is a tendency to reach the maximum torque required larger deflector angle. Then at a certain point, the torque will decrease when the deflector angle is enlarged.

Performance Study of Installed an I-65o Type Cylinder at The Upstream of Returning Blade of Savonius Wind Turbine, Comparison With Conventional Savonius Wind Turbine

Performance Study of Installed an I-65o Type Cylinder at The Upstream of Returning Blade of Savonius Wind Turbine, Comparison With Conventional Savonius Wind Turbine

Study of Multiple Half Blades Effect on the Performance of Savonius Rotor: Experimental Study and Artificial Neural Network (ANN) Model

Objectives: To estimate and compare the performance in terms of torque and mechanical power of a new configuration of Savonius rotors with the conventional one. Methods/Statistical Analysis: New configuration comprises multiple half blades added to conventional configuration. Two different new configurations with different half blade geometries and locations were designed. The torque and mechanical power of the rotor was measured experimentally at various wind speeds and rotor positions. The tests were done 4-6 times for each measurement and the results were averaged. Moreover, the measured data were predicted using Artificial Neural Network (ANN). Findings: The location of half blades effect the performance of the rotor. Additionally, both new configurations of Savonius rotors are associated with above 45% increase in mechanical power compared to the conventional Savonius wind turbine. Based on the simulated results, it is found that the R2 value within a range of 0.902-0.99, which indicated a very good fit of the measured data with the calculated data. Application/Improvements: ANN technique can be applied as a powerful tool and effective way in predicting and assessing the performance of the rotor (torque and mechanical power). Keywords: ANN, Experimental Study, Multiple Half Blades, Performance, Savonius Rotor

Blade shape optimization of the Savonius wind turbine using a genetic algorithm

The Savonius wind turbine is one of the best candidates for harvesting wind energy in an urban environment, due to unique features such as compactness, simple assembly, low noise level, self-starting ability at low wind speed, and low cost. However, the conventional Savonius wind turbine with semicircular blades has a relatively low power coefficient. This work focuses on optimizing the shape of the blade of the Savonius wind turbine to further improve its power coefficient. An evolutionary-based genetic algorithm (GA) is incorporated into computational fluid dynamics (CFD) simulations, thereby coupling blade geometry definition with mesh generation and fitness function evaluation in an iterative process. Three variable points along the blade cross-section are used to define the geometry of the blade arc, and the objective function of GA is set to maximize the power coefficient. Two-dimensional flow around the wind turbine is modeled by the shear-stress transport (SST) k-ω turbulence model and solved through the finite-volume method in ANSYS Fluent. Three GA optimization runs with different population and genetic operations have been carried out to provide the optimal shape of the blade of the Savonius turbine. Compared to the wind turbine with semicircular blades, the wind turbine with optimal blades and a tip speed ratio (TSR) of 0.8 achieved significant improvement (up to 33%) on the time-averaged power coefficient. In addition, the Savonius turbine with optimal blades outperformed the one with semicircular blades at a wide range of TSR (= 0.6–1.2), suggesting that the Savonius wind turbine with optimal blades has great potential to be applied in the real urban environment. The aerodynamic forces and flow structures pertaining to both wind turbines with optimal and semicircular blades are compared and discussed, to improve our understanding on their underlying mechanisms and to further improve their performance.

Flow Field and Performance Study of Vertical Axis Savonius Type SST Wind Turbine

Abstract It has been suggested that waste heats or naturally available heat sources can be utilized to produce swirling flow by a design similar to that of split channels which is currently used to initiate fire whirls in laboratories. A new hybrid power system has been proposed combining the conventional Savonius wind turbine and split channel mechanisms. Previous computational and experimental works indicate a performance improvement in the new hybrid design (named as swirling Savonius turbine, SST) compared to the conventional Savonius turbine. However, the lack of detailed descriptions of the flow field around the swirling Savonius turbine inhibits complete understanding of performance of the hybrid power system. The aim of this study is to numerically explore the three-dimensional unsteady flow around the rotor, and develop a simulation method for predicting their aerodynamic performance using control volume based CFD package of ANSYS CFX. Sliding mesh feature of CFX allowed to solve the motion of the moving blades. Numerical simulations results of SST were compared with the experimental results. A discussion on the detailed flow field characteristics, including velocity vector, velocity streamlines, pressure distribution, vorticity analysis, and examination of power and torque coefficients behavior are presented.

CFD Analysis of a Finite Linear Array of Savonius Wind Turbines

Vertical axis wind turbines such as Savonius rotors have been shown to be suitable for low wind speeds normally associated with wind resources in all corners of the world. However, the efficiency of the rotor is low. This paper presents results of Computational Fluid Dynamics (CFD) simulations for an array of Savonius rotors that show a significant increase in efficiency. It looks at identifying the effect on the energy yield of a number of turbines placed in a linear array. Results from this investigation suggest that an increase in the energy yield could be achieved which can reach almost two times than the conventional Savonius wind turbine in the case of an array of 11turbines with a distance of 1.4R in between them. The effect of different TSR values and different wind inlet speeds on the farm has been studied for both a synchronous and asynchronous wind farm.

Geometrical optimization of a swirling Savonius wind turbine using an open jet wind tunnel

It has been suggested that waste heats or naturally available heat sources can be utilized to produce swirling flow by a design similar to that of split channels which is currently used to initiate fire whirls in laboratories. The new design combines the conventional Savonius wind turbine and split channel mechanisms. Previous computational and preliminary experimental works indicate a performance improvement in the new design (named as swirling Savonius turbine) compared to the conventional Savonius design. In this study, wind tunnel experiments have been carried out to optimize the swirling Savonius turbine geometry in terms of maximum power coefficient by considering several design parameters. The results indicate that the blade overlap ratio, hot air inlet diameter and the condition of the top end plate have significant influence on power and torque coefficients, while a larger aspect ratio and closed top end plate have some favourable effects on the performance. The optimum configuration has been tested in four different wind velocities to determine its influence on the performance, and power coefficients were found to be higher in high wind velocities. The performance comparison of optimum configuration with conventional Savonius rotor showed an increase of 24.12% in the coefficient of power.

Effects of Wind Angles and Wind Speeds on Voltage Generation of Savonius Wind Turbine with Double Wind Tunnels

This paper proposes effects of wind angles and wind speeds on capability of voltage generation of a savonius wind turbine with double wind tunnels. The savonius wind turbine under the study was designed to convert wind flows with opposite directions, such as wind flows due to the movement of vehicles that could be seen at the isles, into electricity. The prototype wind turbine had both diameter and height of 32 cm and had its shaft connected to an electric DC generator. Two tunnels with input and output wind areas of 1,980 and 782 cm2 each were used to increase wind speeds by 2.5 times for the turbine. The experimental results showed that the wind angles between 23.2 – 35.5 degrees provided high levels of generated voltages when the wind angle of 30 degrees provided the highest voltage among the wind angles of 0-90 degrees. The faster the wind speeds, the higher levels of generated voltage, i.e. the wind turbine generated peak voltage between 7.28-11.28 volts for the wind speeds between 4.86-6.41 m/s. In addition, the savonius wind turbine with double tunnels could generate output voltage at almost all the wind angles (60 to -75 degrees) whilst the conventional savonius wind turbine without tunnels could generate voltage only in the wind angle range of 17-38 degrees, as well as, with higher voltage levels for all wind speeds approximately by 45-68%.

Experimental and computational evaluation of Savonius hydrokinetic turbine for low velocity condition with comparison to Savonius wind turbine at the same input power

• Experimental and computational studies of Savonius hydrokinetic turbine. • Performance investigation of Savonius hydrokinetic turbine in low velocity condition. • Insight of design information on this turbine’s performance in low velocity condition. • Savonius hydrokinetic turbine versus Savonius wind turbine at the same input power. • Analysis of enhanced performance of the former turbine by flow characteristics studies. The extensive depletion of the conventional sources of energy has forced the mankind to explore every possibilities lying beneath the nature. The evolution and modification of the old ideas from the field of wind turbine led the mankind to explore the same technology in water. Hydrokinetic turbine, one of the most emerging technologies for power generation, has gained keen interest of the researchers because of some of the unique properties of water like higher specific weight, higher momentum than air for same velocity etc. The objective of the study is to evaluate how the conventional Savonius wind turbine performs when it rotates by the momentum of water current at low velocity from 0.3 m/s to 0.9 m/s in an open water channel. An experimental investigation along with computational fluid dynamics (CFD) study using Ansys 14.0 has been carried out to accomplish the objective of the work. To understand the significance of Savonius design in water application, the performance of the hydrokinetic turbine is experimentally compared to the identically designed wind turbine for the same input power values, showing enhanced performance of the former turbine. The purpose of using CFD is to enable a more detailed study on the velocity and torque distribution across the hydrokinetic turbine and hence to develop more insight of design information about its performance under low velocity condition. Finally the reason for enhanced performance of the hydrokinetic turbine is investigated from the computational study of flow characteristics of both the hydrokinetic and wind turbines. Smooth, stable operation and a good service life of the hydrokinetic turbine could be expected unlike the wind turbine.