Savonius Wind Turbine Research Articles

Flow Dynamics and Performance Enhancement of Drag-Type Savonius Wind Turbine with a Novel Elliptic-Shaped Deflector

Flow Dynamics and Performance Enhancement of Drag-Type Savonius Wind Turbine with a Novel Elliptic-Shaped Deflector

Savonius wind turbine blade selection based on computational fluid dynamics

The Savonius vertical axis wind turbine is widely used because of its simple design and efficiency at low wind speeds. The next development is the mini multi-blade Savonius helical wind turbine. At this miniature size, the performance of a mini multi-blade helical Savonius turbine due to variations in the number of blades and its impact on the energy produced has not been investigated in depth. Therefore, adjustments to the size and number of blades need to be made to optimize the performance of this turbine. The research aims to obtain the performance of the Savonius type S wind turbine with 3 blades and 4 blades using the CFD (Computational Fluid Dynamics) method. The main dimensions of the simulation model are the shaft diameter of 0.008 m, the outer diameter of 0.24 m, the height of 0.4 m, and the number of blades 3 and 4. The inner diameter of the 3-blade turbine is 0.21 m while the inner diameter of the 4-blade turbine is also 0.21 m. Both turbine models are subjected to wind speeds of 4 m/s, 5 m/s, and 6 m/s. Based on the simulation results, a turbine with 4 blades has more optimal performance compared to the 3-blade type. At a wind speed of 6 m/s, the 4-blade Savonius helical turbine produces a rotation of 498,215 rpm and a maximum power of 6,129 watts. Meanwhile, the Savonius turbine with 3 blades at a wind speed of 6 m/s produces a rotation of 545,655 rpm and a maximum power of 4,390 watts. This difference in performance shows the importance of adjusting the number of blades in wind turbine design to achieve optimal efficiency. This research provides useful insights for the further development of mini helical Savonius wind turbines in various wind conditions

Numerical Study on the Effect of Installing Circular Cylinders in Front of the Returning Blade and Beside the Advancing Blade of the Savonius Wind Turbine

Previous research has proven that placing a disruptive cylinder in front of the Savonius wind turbine’s returning blade can significantly increase the performance of the Savonius turbine. In this study, two-dimensional unsteady simulations with a quadratic pave-type structured mesh showed that the circular cylinder placed in front of the returning blade and next to the advancing blade provides the best performance results at a free flow speed of 5 m/s and a Reynolds number of 100,000. In this study, the comparison with experimental data from another study is utilized. The Savonius turbine is installed with an interfering cylinder in front of the returning blade and next to the advancing blade; the air is tighter on the concave side of the advancing blade. The coefficient pressure difference between the convex and concave sides of the blade increases. The maximum moment is achieved in the turbine with a disturbance cylinder at a configuration distance of S/D 1.4 – Y/D 1.61. The maximum moment coefficient is obtained at the position θ = 15°. The placement of two cylinders with a ratio variation of 0.5 D can significantly influence turbine performance. Results show the turbine provides the highest Power Coefficient when TSR = 0.6. The power coefficient increased by 25.11% compared with that of conventional Savonius turbines. Therefore, it can be concluded that the turbine is the optimal configuration for generating the highest power.

A Novel Wind Energy Gathering Structure for the Savonius Wind Turbine and Its Parameter Optimization Based on Taguchi’s Method

An auxiliary structure can significantly improve the wind-trapping capacity of the Savonius wind turbine. In this study, a novel auxiliary structure called a wind energy gathering structure (WEGS) is proposed, and its five parameters, namely the lengths of the shrinkage and diffusion tubes, the length of the centerboard, the length of the throat, the length of the wind board, and the shrinkage and diffusion angles, are investigated using computational fluid dynamics (CFD) and Taguchi’s method. Meanwhile, Taguchi’s method and ANOVA reveal that among the studied parameters, the shrinkage and diffusion angles, the length of the centerboard, and the lengths of the shrinkage and diffusion tubes have a more significant influence on the performance of the WEGS. At a tip speed ratio (TSR) value of 1 and a wind speed of 7 m/s, the optimized combination of the WEGS parameters obtained by Taguchi’s method improves the mean torque coefficient of the turbine by 42.1%. Moreover, at other TSRs (0.6–1.2), the turbine with the WEGS also outperforms an open turbine in terms of aerodynamic (increases of 20.1–53%) and lifetime performance.

Data-driven multi-objective optimization of aerodynamics and aeroacoustics in dual Savonius wind turbines using large eddy simulation and machine learning

Savonius rotor is a popular form of vertical-axis wind turbine (VAWT) for small-scale and urban applications because of its straightforward design and self-starting ability. Dual VAWTs present challenges in terms of wake interactions and noise, particularly in urban areas. Optimizing these parameters is essential for future wind energy adoption. This research is the first to analyze how the interaction of wakes from adjacent rotors, combined with a deflector, affects both the aerodynamic performance and noise levels of dual Savonius rotors. Large Eddy Simulation is applied, as it effectively captures detailed turbulent wind flows and their interactions with wind turbines. A multi-objective optimization method combining Machine Learning and Computational Fluid Dynamics (CFD) is developed to optimize rotors for maximum power efficiency and minimum noise, considering their wake interactions with a unique deflector system. First, the influence of geometric parameters on aerodynamics and aeroacoustics characteristics of rotors is analyzed, and the database is generated using Design of Experiment approach. Next, the CFD model is replaced by Artificial Neural Network (ANN) model established for predicting rotor performances. A Multi-Objective Genetic Algorithm method is used to optimize aerodynamics and aeroacoustics characteristics of rotors. Finally, optimal design parameters are identified from the Pareto front using the technique for order of preference by similarity to ideal solution decision-making method. The ANN model demonstrated high accuracy with an RANN2 of 0.995 and 0.971 for the average power coefficient (CP) and overall sound pressure level (OSPL) predictions, respectively. Multi-objective optimization revealed the best configuration of the deflector with bleed jets, improving the average CP up to 57.5% and reducing OSPL to an almost 5.2% compared to the dual rotor case at TSR = 0.8.

Enhancing Savonius Rotor Performance with Zigzag in Concave Surface-CFD Investigation

Savonius, a type of vertical-axis wind turbine (VAWT), is suitable as an appropriate small-scale energy conversion apparatus for regions with relatively low wind speeds, such as Indonesia; however, it exhibits sub-optimal efficiency. One potential approach to improving the efficiency of Savonius turbines is to increase the drag force on the concave surface of the blades. In this case, the dissimilarity in the forces experienced by the two blades can be increased, resulting in a corresponding increase in torque. This investigation aims to assess and compare the power coefficient (Cp), torque and drag coefficient (Cd) of the conventional Savonius rotor with the zigzag pattern implemented in the middle area of the concave surface of the blades at low wind speeds. The efficiency can be achieved by implementing the k-ω shear stress transfer (SST) turbulent model and 3D computational fluid dynamics simulation at tip speed ratio (λ) 0.4-1 with a velocity inlet of 4, 5, and 6 m/s. The study results show that using the zigzag pattern on the concave surface led to an 18.8% boosted in Cp of at λ = 0.8 and an inlet velocity (U) = 5 m/s compared to the standard Savonius rotor model. In this case, the efficiency of the Savonius wind turbine may be enhanced by incorporating a zigzag pattern in the middle of the concave surface of the Savonius rotor.

Numerical investigation of turbulent flow over a small-scale vertical axis wind turbine

The present paper aims to analyse the aerodynamics of turbulent fluid flow over a vertical axis wind turbine (VAWT). A 2D study is carried out for a two-bladed SAVONIUS wind turbine, where the rotor diameter is D=20cm. The governing equations (Unsteady Reynolds Averaged Navier Stokes URANS) are solved numerically using a CFD (computational fluid dynamics) open-source code based on the finite volume method; the SST turbulence model is applied for the system closure. An arbitrary mesh interface (AMI) technique is applied at the sliding interface boundary, which is a circular surface separating between the rotating zone and the fixed zone where the mesh remains stationary. The numerical results allow predicting the vorticity and pressure distributions over a rotating wind turbine for different tip speed ratios in order to characterize the generated wake. The velocity deficit is calculated for different positions behind the rotor to characterize the disturbance rate of the flow.

Performance Investigation of the Savonius Wind Turbine by Putting a Rotating Cylinder in the front of Advancing by Varying the Diameter and Stagger Angle

Performance Investigation of the Savonius Wind Turbine by Putting a Rotating Cylinder in the front of Advancing by Varying the Diameter and Stagger Angle

Aerodynamic analysis of a small-scale Savonius wind turbine incorporated with wind lenses: A CFD approach for wake pattern and power prediction

Aerodynamic analysis of a small-scale Savonius wind turbine incorporated with wind lenses: A CFD approach for wake pattern and power prediction

Design optimization of two-blade Savonius wind turbines for hydrogen generation

This paper presents a Taguchi optimization study aimed at enhancing the efficiency of a two bladed Savonius wind turbine by optimizing inner blade parameters. An L9 orthogonal design was created, and one-way analysis of variance (ANOVA) was conducted to assess the impact of each parameter on wind turbine performance. Optimal blades configuration was determined using the Taguchi method and power curve of the wind generator was created. Furthermore, a MATLAB – Simulink model was developed to simulate a hydrogen production system based on an alkaline electrolyser fuelled with the electrical energy produced by the optimized wind turbine. Wind speeds data of Vieste, a small town located in the Gargano promontory of Puglia region, South of Italy, were chosen for yearly based simulations. The ANOVA analysis shows that the most effective parameter on the performance of the optimized turbine was determined as the inner blade angle by 91.85 % and the least important parameter was calculated as the number of inner blades, by 0.98 %. Furthermore, the potential annual hydrogen generation for different numbers of wind turbines was calculated through the MATLAB – Simulink model: 2.423 kg for a single turbine, 25.93 kg for five turbines, and 57.58 kg for ten turbines.

Evaluation of a Savonius wind turbine in the vicinity of a circular cross-sectional building

Today's urban areas are filled with tall buildings that require significant energy. To enable the implementation of small-scale wind turbines for dispersed electricity generation in cities, it is crucial to evaluate their performance in close proximity to buildings. This study aims to assess the performance of conventional Savonius rotors near a circular cross-sectional building for the first time. The performance of a Savonius wind rotor is being studied at different installation angles (30°, 45°, 60°, and 90°) with a constant non-dimensional gap space (S/D) of 2.0 between the rotor center and building envelope under a constant free-wind speed of 6 m/s. Two possible wind rotor rotation scenarios, inward and outward, are thoroughly tested and studied. Computations are carried out for tip speed ratios (TSR) of 0.4, 0.8, and 1.2. The obtained results are successfully validated for both the Savonius rotor in the free-wind flow (without a building) and a circular cross-sectional building (without a wind rotor) as well. The results show that installing a Savonius rotor at angles of 60° and 90° provides the maximum power coefficient based on the TSR. In contrast, placing the rotor at 30° reduces its performance even more than the reference case. For optimal rotor angles, inward rotation is preferred over outward rotation regardless of the TSR. Finally, there are improvements of 208.72 %–439.95 % compared to the reference case for 60° and 90° under inward rotation.

Comparison of Non-Overlap and Overlap Savonius Wind Turbines in the Physics Aspect Using Computational Fluid Dynamics Method

Abstract Wind energy has good potential as a renewable energy source. Savonius-type wind turbines can provide power generation at a low cost with minimal environmental impact. Due to its low efficiency, researchers were focused on increasing it through many methods, such as applying twisted-bladed, optimizing the blade shape, and applying overlap. Most researchers have studied the effects of overlap on Savonius blades only in terms of performance improvements. This study evaluates the effect of overlap on the Savonius blade from a physics perspective using the Computational Fluid Dynamics method to get a new approach based on the improvement. The models are 2-bladed Savonius with non-overlap and 0.2 overlap. The main software used is Ansys Student 2023 R2. The turbulent model chosen is a realizable k- enhanced wall treatment. Then, pressure and velocity coupling were done using SIMPLE: 2nd order upwind, 1st order implicit. As a result, the overlap model has a higher reverse flow but lower pressure for all Tip Speed Ratio. Another finding shows that turbulent kinetic energy decreases with overlap. For the non-overlap model, the amount of turbulence is greater downstream, which causes vortices to form and lowers turbine performance. So, the effects of the overlap blade result in higher average Torque Coefficient than non-overlap.

Enhancement of aerodynamic performance of Savonius wind turbine with airfoil-shaped blade for the urban application

The present study introduces a novel rotor configuration with an airfoil-shaped blade, based on the low-speed high-lift FX74-CL5-140 airfoil, for enhancing the performance of the Savonius wind turbine for a practical application in urban areas. The preferment of the present design over the original one with a semicircular shape is confirmed by the sequence of unsteady two-dimensional (2D) numerical simulation. The results demonstrate a new power coefficient peak (up to 16.5 % better than that of the original rotor) could be gained at the tip speed ratio (TSR) of 1.1. The effective working range is further extended to TSR > 0.7 compared to that at TSR > 1.0 in the literature. Insight into the flow dynamic, including pressure, velocity, streamline, and wake analysis, reveals that the thick blade near the overlap region, benefiting in terms of the turbine’s high performance. The airfoil blade increases the momentum energy around the rotor, changes the pressure on the concave side, and varies the origin of the pressure force, leading to an increase in the moment arm with more torque exhibited on the rotor at high TSR. In addition, the proper orthogonal decomposition (POD) analysis is also performed to better understand the flow phenomena behind the rotor. Overall, the present design is beneficial for urban applications because it can enhance the rotor performance without losing the omnidirectional and compactness features.

CFD investigation on wind power harvesting from small-scale wind turbines for powering residential buildings in New Zealand

ABSTRACT As an alternative solution, wind power could be harnessed by designing and implementing small-scale wind turbines for distributed power generation. In this work, 3-dimensional time-domain numerical simulations, based on the Reynolds-Average Navier-Strokes (RANS) model, are conducted for two categories of small-scale wind turbines, i.e. drag force- (Savonius) and lift force-driven (Darrieus) ones, while placing them at a flat surface and a step height, respectively. The present results confirmed that placing a small-scale wind turbine at a step height can improve the maximum power output, respectively, approximately 219.2% for the Savonius wind turbine and 121.0% for the Darrieus wind turbine operating at their optimum stage; moreover, the corresponding peak power spectral density of the turbine torque is improved by 173.9% and 83.6%, respectively. In addition, the power generated from the wind flow could reduce the CO2 emission. It has been observed that the Savonius turbine could reduce the annual CO2 emission by 3,738.9–19,857.8 kg and that of Darrieus turbines by 4,919.6–26,128.8 kg. This study demonstrated the benefits of adopting forward facing steps to improve wind turbine performance in a typical urban environment.

Comparison of 2D and 3D Simulations on Predicting the Performance of a Savonius Wind Turbine

The performance of Savonius rotors plays a vital role in harnessing wind energy for various applications. This study aims to investigate and compare the performance characteristics of Savonius rotors using two-dimensional (2D) and three-dimensional (3D) analysis approaches. The primary objective is to determine the optimal analysis method for evaluating the rotor's performance. The simulations were conducted using ANSYS software, considering six different tip-speed ratios (TSRs) ranging from 0.2 to 1.2, and three wind speed categories (7 m/s, 5 m/s, and 3 m/s). The hybrid shear-stress transport (SST) k-omega was used as the turbulence model. The results indicate that the 2D analysis approach, which simplifies the rotor's geometry by assuming rotational symmetry, provides reasonable estimations of the rotor's performance. However, the 3D analysis captures the intricacies of the rotor's actual geometry, accounting for the effects of non-uniform flow and vortex shedding, which can significantly influence the rotor's performance. The comparative analysis reveals that the 3D analysis predicts higher torque and power coefficients than the 2D approach, especially at higher wind speeds. At TSR 1.0, the torque and power coefficient obtained from the 3D approach are 6.56 Nm and 0.102, respectively meanwhile 2D approach gains 6.28 Nm torque and 0.098 for power coefficient. This research contributes to a better understanding of the performance characteristics of Savonius rotors and highlights the importance of considering three-dimensional effects in their analysis. The findings can guide the design and optimization of Savonius rotor systems, leading to improved wind energy conversion efficiency and enhanced utilization of renewable energy resources.

Investigation of The Effect of Phase Angle on The Aerodynamic Performance of Three-Bladed Helical Savonius Wind Turbines Using Computational Fluid Dynamics Method

In this study, the effect of the phase angle of the semicircular blades between the stages on the aerodynamic performance of the three-blade, double-stage helical Savonius wind turbines (HSWT), which are vertical axis wind turbines, was examined by the computational fluid dynamics (CFD) method. In the Savonius wind turbine system, the drag force effect provides the most significant contribution to aerodynamic performance. Performance improvements that can affect drag force can provide significant advantages. For this purpose, three-bladed double-stage helical Savonius rotors with eccentricity L/H=1/2 and phase angles of the semicircular blades between the stages Ɵ=0°, 45° and 90° were designed. Solidworks R2018 is used for designs and ANSYS-Fluent 18.1 programs are used for analysis. The turbine with L/H=1/2 and Ɵ=90° was produced on a 3D printer and tested experimentally. Experiments were carried out in the T-490 air tunnel. The results obtained were used as a reference for numerical analysis and the ideal turbine model was tried to be determined. 10 different air velocities ranging between 3.83-20.35 m/s were used in the numerical analysis. As a result, an 11.64% increase in the drag force was observed by changing the phase angle from 0° to 45° in HSWT 1/2s. By changing the phase angle from 0° to 45° in HSWT 1/2s, a 10.77% rise in the drag coefficient was observed. It has been evaluated that the HSWT efficiency improved with the increment in drag force.

A Numerical Analysis on the Performance and Optimization of the Savonius Wind Turbine for Agricultural Use

Given the state of the world nowadays, renewable energy is becoming more and more essential rendering wind turbine electricity quite important. Its shape and the fact that the Savonius vertical axis wind turbine runs at relatively low wind speeds with high torque values makes it suitable for practical uses such as that of an irrigation system in agriculture industry. This paper utilizes numerical research with Computational Fluid Dynamics (CFD) to investigate the performance of a vertical-axis wind turbine. The ANSYS CFD program was engaged to construct the simulations during the pre- and post-processing stages. Wind speed remained constant while the angular velocity was altered to enable analysis of the flow through the wind turbine. Because of its mechanical simplicity, the primary profile of a semicircle has remained a typical option for turbines that generate high torque based on drag force. The effects of using elliptical curves and the fluctuation in thickness along the profile chord were both examined in this study. Equivalently, an attempt to optimize the rotor's design was made. After the performance of a numerical simulation, a geometry consisting of simple circle arcs was developed, with a 10.9% improvement in the power coefficient, analogous to prior optimizations with more complicated geometries. The numerical results derived include the torque coefficient evolution throughout a full rotation as well as the distribution of vorticity magnitude at different rotor points.

Study on the Load Cell Utilization for Dynamic Torque Measurement in 3-Blade Savonius Wind Turbine Design

This paper presents the design and analysis of a Savonius wind turbine. Wind turbines harness wind energy to generate electricity, presenting a renewable and clean alternative to traditional power sources. This savonius wind turbine is a type of wind turbine that can rotate even at relatively low wind speeds, so it is necessary to develop a measuring instrument that has high accuracy and is affordable to evaluate the performance of this turbine. In this research, a load cell with an affordable price with a percentage error of approximately 15%, is used as a dynamic torque measurement tool on wind turbines, this torque parameter can be used as an important performance determinant of the wind turbine in generating power. This research was conducted in the Agricultural Machinery Workshop and Integrated Laboratoryy, University of Sumatera Utara, Medan from March to August 2022. The research is performed in several phases, which are 3D design, simulation, schematic design, prototype making, collecting actual data, analyzing actual data, and simulation data. The simulation results are compared with the actual data from the loadcell that has been tested, from the results of the comparison the accuracy value and deviation value of the instrument will be obtained.

On the rotation of a Savonius turbine at low Reynolds numbers subject to Kolmogorov cascade of turbulence

With an increasing demand for small energy generation in urban areas, small-scale Savonius wind turbines are growing their share rapidly. In such an environment, Savonius turbines are exposed to low mean velocity with highly turbulent flows made by complex geographies. Here, we report the flow-induced rotation of a Savonius turbine in a highly turbulent flow (18% turbulence intensity). The high turbulence is realized by using the far-field of an open-jet. Compared to low turbulence inflow (1% turbulence intensity), the turbine rotates 4% faster in high turbulence since the torque/power increases with turbulence intensity. The wake measurement by hot-wire anemometry and particle image velocimetry reveals the suppression of vortex shedding in high turbulence. In addition, a newly developed semi-empirical low-order model, which can include the effect of turbulence intensity and integral length scale, also confirms high turbulence intensity contributes to the rotation of the turbine. These results will boost more installation of small Savonius turbines in urban areas in the future.

Performance of Savonius Wind Turbine Affected by Circular Cylinder Beside Advancing and in front of Returning Blade: Experimental Method

This study investigates the influence of circular cylinders positioned beside the advancing blade and in front of the returning blade on the performance of a Savonius wind turbine. The experimental method focuses on assessing how these cylinders affect the turbine’s efficiency and self-starting capability. Various distances between the cylinders and the turbine blades (S/D = 1.4) and different cylinder positions (Y/D = 1.27, 1.32, 1.37, 1.42, 1.51, 1.61, 1.71, 1.82, 2.00) were explored. Tests were conducted under constant speeds corresponding to Reynolds numbers of Re = 120,000 and 150,000. Preliminary findings of all various distances indicate a significant improvement in turbine performance, particularly in enhancing self-starting ability, when using these disturbance cylinders compared to conventional designs. Specifically, the configuration with cylinders positioned at S/D = 1.4 and Y/D = 1.51 demonstrated the most promising results, showing the static torque coefficient a 48% increase in performance at a wind speed of 6 m/s and a remarkable 78% increase at 7 m/s. These results highlight the potential of utilizing circular cylinders strategically around Savonius wind turbines to optimize their performance and operational efficiency.