Performance Of Savonius Wind Turbine Research Articles

Simulation of Overlap Effect on Savonius Wind Turbine Performance by Varying Cylinder Distance in Front of Returning Blade

Simulation of Overlap Effect on Savonius Wind Turbine Performance by Varying Cylinder Distance in Front of Returning Blade

Numerical investigation into performance of Savonius wind turbine equipped with inner blades: Overlap ratio effect

This research focuses on the effect of overlap ratio on the performance of Savonius rotor in the presence of inner blades in such a way that inner blade tip is parallel to the main blade tip and root. Findings reveal that at low overlap ratios, using inner blade that the inner blade tip is parallel to the main blade root leads to a higher power and torque coefficients than the other inner blade configuration and also conventional rotor. This research indicates that for the overlapped rotor and for the two inner blade configurations, the higher power and torque coefficients could be obtained at high and low tip speed ratios, respectively. Results show that for both inner blade configurations, the overlapped rotors overcome the negative torque generated by the non-overlapped one. It is also shown that at high overlap ratio, using inner blade has no advantage over the conventional rotor.

Predicting aerodynamic performance of savonius wind turbine: An application of generalized k-ω turbulence model

Savonius wind turbine (SWT) is one of the popular vertical axis wind turbines (VAWT) used for energy harvesting applications. In this study, the aerodynamic performance of the SWT is numerically investigated by coupling an efficiency two-dimension (2D) unsteady Reynolds-Averaged Navier-Stokes (URANS) simulation with a generalized k-ω (GEKO) turbulence model. The numerical method is first validated against the available experimental data before further carrying out to examine the applicability of the GEKO model for various flow scenarios and rotor configurations, including the overlap and non-overlap geometries. The analysis reveals high sensitivity of the computed torque (CT) and power (Cp) coefficients to the model empirical constants such as the separation parameter Csep, the near wall parameter Cnw, and the jet flow parameter Cjet. Although showing a good agreement in Cp with the measured data of the non-overlap configuration, an excessive prediction of Cp with a maximum error of 39% is produced at the tips speed ratio over 0.8 in the overlap one by the default GEKO model. Meanwhile, a satisfactory prediction with the experimental data with a maximum deviation of 6.7% can be achieved with the new set of model empirical constants, resulting in a better capturing of the flow-induced rotor such as the flow separation-attaching, vortex, and turbulent quantities.

Savonius Wind Turbine Performance Comparison with One and Two Porous Deflectors: A CFD Study

Savonius Wind Turbine Performance Comparison with One and Two Porous Deflectors: A CFD Study

Savonius wind turbine blade design and performance evaluation using ANN-based virtual clone: A new approach

The drag based Savonius wind turbine (SWT) has shown immense potential for renewable power generation in built-up areas under complex urban wind conditions. While a series of studies have been conducted on improving SWT's efficiency, optimal performance has yet to be achieved using traditional design approaches such as experimental and/or computational fluid dynamics methods. Recently, artificial intelligence and machine learning have been widely used in design optimization. As such, an ANN-based virtual clone can be an alternative to traditional design methods for wind turbine performance determination. Therefore, the main goal of this study is to investigate whether ANN-based virtual clones are capable of determining the performance of SWTs with a shorter timeframe and minimal resources compared to traditional methods. To achieve the objective, an ANN-based virtual clone model is developed. Two sets of data (computational and experimental) are used to validate and determine the efficacy of the proposed ANN-based virtual clone model. Using experimental data, the model's fidelity is over 98%. The proposed model produces results in one-fifth the time of the existing simulation (based on the combined ANN + GA metamodel) method. The model also reveals the location of the dataset's optimized point for augmenting the turbine's performance.

Effect of the Phase-Shift Angle on the vertical axis Savonius wind turbine performance as a renewable-energy harvesting instrument

Wind energy is the third-largest renewable energy source after hydro and solar energy, so it has great potential in increasing renewable energy as a percentage of national energy. However, wind energy installation is only at 0.25% of the existing potential; so, it still needs to be developed. One of the development efforts is to optimize the wind turbine rotor design. Savonius rotors are among the most popular rotors to convert wind energy into electrical energy. The Savonius turbine is a simple structure, easy to modify to upgrade Savonius performance, and can be operated at low velocity. Phase-shift angles of 0°, 30°, 60°, and 90° were utilized in this study on a two-stage Savonius wind turbine. This study was carried out using Solver CFX utilizing the Computational Fluid Dynamic technique on the ANSYS Student version software. An SST (shear stress transport) turbulence model with steady-state turbulence was used. The purpose of this study was to assess the influence of PSA on the performance of the Savonius two-stage turbine. Factorial design analysis was used in conjunction with the CFD approach. The results indicated that PSA influenced the Savonius turbine’s performance, with 30° being the optimal PSA. Simultaneously, the Cpmax may be obtained using 0.29. The factorial design study with two components revealed that the Phase-Shift Angle had a considerable effect on rotor performance, and the two factors (TSR and PSA) had an interaction.

Enhancing the aerodynamic performance of a Savonius wind turbine using Taguchi optimization method

ABSTRACT Savonius wind turbines are a type of vertical axis wind turbine. In this research, the effect of some design parameters such as blade type, overlap ratio, separation distance, and blade thickness on the aerodynamic performance of a two-bladed Savonius wind turbine with the rotor diameter of 0,3 m was investigated numerically by using a realizable k-epsilon turbulence model. Three different levels were selected for each parameter. Computational fluid dynamics analyses were performed using Fluent software and the Taguchi method was used for the optimization process. It was seen that a Savonius rotor with an elliptical blade that has a 2 mm thickness, a 0,15 overlap ratio, and a 7,5 mm separation distance shows the best aerodynamic performance. The difference between the aerodynamic performances of the base and the optimized rotor was found to be greater at higher tip speed ratios than at lower tip speed ratios. The power coefficient was raised by nearly 17,9% for a tip speed ratio = 0,8. The optimal tip speed ratio value was changed from 0,8 to 1,0, after the optimization process.

Effect of the variations of the gap flow guides geometry on the savonius wind turbine performance: 2D and 3D studies

The Savonius wind turbine has been identified to have low power and torque coefficients. Numerous blade shapes and modifications have been proposed to improve its performance. In the present study, double gap flow guides of different lengths of 25–100 mm were introduced at different angular positions of 45–90° in a 0.5 m diameter blade Savonius turbine. The unsteady Reynolds Averaged Navier Stokes equations and the turbulence equations corresponding to SST k−ω were solved using the commercial software ANSYS FLUENT. Simulations were conducted in 2D and validated with 3D simulations at key points. The extracted results of the coefficient of performance and torque were compared with the available experimental data for the purpose of validation. A maximum increase of 12.24% in the coefficient of performance was observed for model 75 (degree angle) - 75 (mm length) at a tip speed ratio 1. Despite the high performance of model 75-75, model 60–75 showed a higher average of coefficient of performance across the considered range of tip speed ratios. The advantage of gap flow guides was explained in light of streamline plots, velocity vector plots and pressure distribution curves.

Effect of flexible blades on the Savonius wind turbine performance

Effect of flexible blades on the Savonius wind turbine performance

Experimental study of the effect of slotted blades on the Savonius wind turbine performance

This study investigates the effect of Reynolds number on the performance of Savonius wind turbine with slotted blades. The turbine performance investigation was based on the torque coefficient (Ct), power coefficient (Cp), and tip speed ratio (TSR). The experiment used two number of blade configuration, blade overlap ratio of 10%, 12.5% and 20%, slotted position of 15%, 20%, 25% and 35%, and also slotted gap width of 3 mm, 5 mm, 7 mm, and 9 mm. The wind speed carried out in this experiment are 5.94 m/s, 6.46 m/s, 6.99 m/s, and 7.27 m/s, which are generated from the fan blowers as a wind source. The Savonius turbine with 10% overlap ratio shows the best performance. The highest Cp obtained is 0.138 by the variation of a 3 mm gap with Re of 1.44 × 104 and 0.526TSR.

Savonius wind turbine performance in high turbulence and its improvement by jet supply

Savonius wind turbine performance in high turbulence and its improvement by jet supply

Performance Improvement in a Helical Savonius Wind Rotor

Above all vertical axis wind turbines, for their lower cost and independent on wind direction, Savonius rotor takes the advantage to be more suitable for some implementation. Thus, many investigations have been carried out to improve its efficiency. This study emphasizes on the effect of the overlap distance and the blade shape on a helical Savonius wind turbine performance. Assessment methods based on the flow field characterizations, the variation of torque and power coefficient are performed. Thus, transient simulations using the SST k–ω turbulence model are carried out. The numerical model is validated using wind tunnel tests. Results indicate that the non-overlapped helical Savonius rotor highlights higher maximum power coefficient of 0.124 at a tip speed ratio of 0.73 over rotors with overlap distance of 10 mm, 15 mm and 20 mm, respectively. In addition, the delta-bladed rotor improves the performance of the helical Savonius rotor by 14.51%. With the novel blade shape, the maximum power coefficient reaches a value of 0.142 at a tip speed ratio of 0.78. The obtained results present an interesting data that could provide the aerodynamic characteristics of the airflow for the designers and engineers to enhance the efficiency of the helical Savonius turbine.

Impact of urban environment on Savonius wind turbine performance: A numerical perspective

In this study, computational fluid dynamics (CFD) is employed to evaluate the influence of surrounding buildings on the performance of a roof-mounted, 2-bladed Savonius vertical-axis wind turbine (VAWT). The latter is planned to be located in the Bovisa Campus of Politecnico di Milano. In the present work a preliminary simulation campaign has been conducted, explicitly depicting the surrounding area and employing an advanced Reynolds-averaged Navier-Stokes (RANS) model. This closure is suitable for Atmospheric Boundary Layer (ABL) simulation, reliably reproducing the various ground roughness elements and employing a Building Influence Area (BIA) for a more accurate representation of the disturbed flowfield. After considering twelve main wind directions, the resulting velocity profiles are extracted and used as inlet conditions for a second session of simulations, related to the wind turbine. The final goal is to reproduce the effect of the surrounding buildings and to accurately forecast the energy production of the machine. This is a relevant aspect of the increasingly topical framework of smart city, implying the exploitation of wind energy. Outcomes indicate that the resulting energy production of the machine remarkably departs from ideal conditions and that accounting for the surrounding topography becomes an aspect of great relevance.

The analysis of wind blade on the performance of Vertical Axis Wind Turbine

The long-term energy crisis is one of the biggest issues of this century that needs to be tackled to ensure a prosperous future for coming generations and wind energy is one of the energy sources that grows rapidly and most promising renewable energy. Vertical Axis Wind Turbine (VAWT) is the best option for small wind turbine project and suitable for low average wind speed environment. In this project, experiment had been carried out to study the effect of wind blade number on the Savonius wind turbine performance at different wind speeds and a comparison had been made to choose the best performance between 2, 3, 4, 5 and 6 blades wind turbine. A small Savonius wind turbine prototype, PicoScope, Digital Anemometer, Digital Tachometer and other equipment were used for this purpose. A PicoScope software with a hardware device had been used to create an oscilloscope and spectrum analyser on the PC. The experiment was carried out in an open room space to acquire a close condition to the real environment. The performance results were analysed and Malaysia’s average wind speed had been used as the guideline for the comparison. It can be deduced that 5 blades rotor gives the best performance compared to the 2, 3, 4 and 6 blades rotor. At wind speed 6.1 m/s, 5 blades rotor produced optimum mechanical power output at 260 mW, power coefficient of 0.109 (10.9 %), torque at 0.12 mN.m and tip speed ratio at 8.28.

A numerical study of the effect of a single cylinder and plate deflector toward the Savonius wind turbine performance

This study has investigated the effect of the circular cylinder placed at the side of advancing and plate deflector placed in front of returning blade. The CFD approach is done to solve the incompressible URANS. The numerical validation is done by comparing the experimental results using torque coefficient data for Cm=0.185 and TSR=1.078. The turbine using conventional Savonius 1 m of diameter and 1 m of height. A circular cylinder have diameter of 0.7D placed at x/D = 0.5D and y/D = 0.7D. The plate deflector is placed at 1D in front and center of turbine by varying the deflector plate on perpendicular free stream in placed in front of returning at distance variations (y/D) of 0, 0.1, 0.2, 0.3 and 0.4 with deflector angle of 30 degree towards the free stream direction and the Reynolds number of 4.32 x105. The study indicates that the deflector and circular cylinder can increase the turbine Performance at y/D of 0.3 in about 9.71 %.

Effect fix drag-reducing on blades to performance of savonius wind turbine

This article proposes a design model for vertical axis wind turbines based on drag forces by adding fix drag-reducing to the blades tested by subsonic wind tunnel with wind speeds of 3-6 m/s and opening angle variations of fix drag-reducing from 0, 15, 30 and 45°. The research explained that at the opening angle of 15° can improve the performance of the wind turbine model significantly at high wind speeds on the contrary for larger angle openings. The addition of fix drag-reducing instead reduces the performance of the wind turbine model considerably on all variations of wind speed tested.

CFD analysis of the effects of multiple semicircular blades on Savonius wind turbine performance

The goal of this work is to simulate and improve the efficiency of an innovative multiple semicircular-bladed Savonius wind turbine, which is identified as belonging to the vertical axis wind turbine (VAWT) category. It is characterized as a low speed turbine that is simpler and cheaper to build than traditional turbines. This makes it appropriate for generating mechanical energy in lower wind speed regions, and it can be coupled with solar panels in urban agglomerations. The objective of this paper is to compare the aerodynamic characteristics and power efficiency of four different geometries of the Savonius wind turbine (two-conventional and two-modified rotors) in order to estimate the most efficient design. The proposed Savonius design comprises multiple semicircular blades added to conventional two- and three-bladed Savonius rotor configurations. The comparison of the efficiency in terms of the torque coefficient (C T ) and power coefficient (C P ) of the new system configurations with the conventional ones finds that the multiple semicircular two-bladed Savonius rotor is more efficient than others. The numerical simulation of the conventional Savonius rotor is developed and validated against experimental and numerical data derived from a literature review. The choice of turbulence model and local or global mesh refinement play essential roles in the accuracy of the numerical simulation results. In this work, we adopted a Shear Stress Transport (SST) model for modelling turbulence, which incorporates the near wall fluctuation capturing capability of the k-w model, and the robust k-ei€ model for modelling the whole numerical domain. An average improvement in the power coefficient of 8.43% for different tip speed ratios (TSRs) is observed for the new configuration compared with the others.

The effect of blade type variations on savonius wind turbine performance

The Savonius wind turbine is one types of vertical wind turbine that can be working in low wind speed conditions. This type of turbine is suitable for development in Indonesia, which has an average wind speed ranging from 3 to 5 m/s. This research presents the results of performance comparisons among three types of turbine blades, namely L, U, and S with each helix 60° and no-load conditions. Turbines are made of alumunium with a thickness of 0.7mm. The dimensions of the turbine are high 0.8m and the rotor diameter 0.46m, and each has three blades. The testing location was carried out on the seashore of Batu Belubang village, Bangka Island, Indonesia. The research was conducted to see how much the blade performance was by measuring the shaft rotation that occurred. From the results of the study, the three turbines showed excellent performance. Where for U blade type, the shaft can rotate up to 559 rpm at 5.5 m/s wind speeds. For type L blades with wind speeds of 5.6 m/s, the beam is capable of rotating up to 430 rpm. While for the type S showed the best performance on 564rpm at a wind speed of 5.5 m/s.

An innovative augmentation technique of savonius wind turbine performance

This work presents an innovative technique to enhance the performance of the Savonius wind turbine. The new technique is based on introducing an upstream deflector and downstream baffle. The shape and location of both devices are optimized using a genetic algorithm. The performance of the turbine with the optimized devices is compared with the single Savonius turbine performance. The study employs the finite volume solver (ANSYS-FLUENT) to solve unsteady Reynolds Averaged Navier–Stokes equations and turbulence model equations. The optimized configuration results in much higher power coefficient than the Savonius turbine. The average peak power coefficient using both deflector and baffle is 0.47 compared to 0.24 of the Savonius turbine. The peak power coefficient of the turbine corresponds to a speed ratio close to unity. This improved performance is attributed to the favorable aerodynamic interaction between the turbine and the downstream baffle which accelerates the flow around the rotor and generates larger turning torque. The baffle generates a jet effect on the advancing bucket and accelerates the flow behind the bucket creating a large zone of negative pressure and thereby increases the driving torque. Furthermore, the upstream deflector (also called shield or curtain) produces a shield for the returning bucket of the turbine which diminishes the adverse effect associated with the returning bucket on the aerodynamic torque of the turbine. This remarkable improvement of turbine performance will encourage the future application of the Savonius wind turbine in small power applications of wind energy.

A NUMERICAL STUDY OF THE TURBULENCE MODEL INFLUENCE ON A SAVONIUS WIND TURBINE PERFORMANCE BY MEANS OF MOVING MESH

This numerical research has investigated the influence of the turbulence model on a Savonius wind turbine performance. The numerical simulation has been applied by using two-dimensional analysis of Computational Fluid Dynamics through moving mesh technique to solve the incompressible Unsteady Reynolds Averaged Navier-Stokes equations. In this study, the turbulence model has used RNG k-epsilon, standard k- epsilon, Realizable k- epsilon, SST k-omega, standard k- omega, and spalart-allmaras. Firstly, the numerical model has been verified by the experimental data towards the torque coefficient at a tip speed ratio (TSR) of 1.078 and has used the Realizable k-epsilon (RKE). Then the turbulence models are compared with experimental data towards torque coefficient at TSR change. The verification has been achieved and compared to the turbulence model variations. The results of numerical simulation reveal that Realizable k-e (RKE) has the performance approach of experimental data within the Cp Error about 1.67% at TSR of 0.9.