Showing papers on "Savonius wind turbine published in 2020"

Nondimensional Parameters’ Effects on Hybrid Darrieus–Savonius Wind Turbine Performance

Abstract: Vertical axial wind turbines are the most commonly used turbines in residential and urban areas. This paper investigates the effect of combining Darrieus and Savonius wind turbines on power output and introduces a wind turbine with high starting torque addition to the wide working domain. A two-dimensional computational fluid dynamics transient simulation is developed, and a moving mesh is implemented for rotating moving parts. Comprehensive research has been carried out to investigate the effects of the initial overlap ratio (ɛ), arc angle Ø, and curvature (α) of Savonius blades on the performance of the turbine and 18 models are simulated at seven tip speed ratios. The results showed that combining the Darrieus turbine with the Savonius turbine has a favorable effect on self-starting performance. Also, it was observed that by changing each of the parameters, the primary model performance could be significantly improved. Finally, it is concluded that ɛ = 0.25, α = 0.25, and ∅ = 150 deg are the optimum values of the parameters which increase turbine power output compared to conventional vertical-axis turbines.

Improving the performance of Savonius wind turbine by installation of a circular cylinder upstream of returning turbine blade

Abstract: The effect of the installation of a circular cylinder upstream of the returning turbine blade on the performance of the Savonius wind turbine was studied experimentally. The experiments are carried out for Re = 99,000. The circular cylinder with a diameter relative to the blade diameter (d/D) = 0.54 was installed at a distance between the circular cylinder and the returning blade relative to the blade diameter (S/D) varied from 1.4 to 2.2. The experimental results indicate that changes in distance S/D may improve the turbine power coefficient, where the maximum power coefficient occurs at S/D = 1.4, which increases in the power coefficient around 12.2% at a tip-speed ratio of 0.65 relative to the conventional one. However, when the circular cylinder is placed away from the returning blade (S/D > 1.8), there is practically no change in the power coefficient.

Improving efficiency of Savonius wind turbine by means of an airfoil-shaped deflector

Abstract: In the present study, a novel deflector system was proposed to improve the performance of a Savonius wind turbine through Computational Fluid Dynamics (CFD) simulation. For this purpose, an airfoil-shaped deflector was proposed and placed in front of the turbine to prevent the negative torque affecting the convex surface of the returning blade and also making it possible for deflecting the wind into the advancing blade. Different configurations of the proposed deflector system were considered numerically using the CFD solver. A three-dimensional incompressible unsteady Reynolds-averaged Navier–Stokes simulation in conjunction with the SST k − ω turbulence model was done and validated with the available experimental data. The predicted results indicated that the performance of the Savonius rotor is highly dependent on the position and angle of the deflector. Thus, there was an appropriate position and angle values to obtain the highest torque and power coefficients. It was concluded that using the favorable airfoil-shaped deflector significantly enhanced the static torque coefficient values in all angular ranges especially in the rotation angles between 0°–30° and 150°–180°. By properly covering the returning blade using the airfoil-shaped deflector, the static torque coefficient values increased up to two times higher than that generated by without deflector case.

A novel blade design for Savonius wind turbine based on polynomial bezier curves for aerodynamic performance enhancement

Abstract: Advanced wind turbine designs and technologies have been evolved to take advantage of wind energy Despite the significant progress already attained, the need for a dependable wind energy converter

Experimental and Theoretical Studies for Improving the Performance of a Modified Shape Savonius Wind Turbine

Abstract: In this paper, measurements and computations are performed to study the performance of a 45-deg twisted Savonius rotor with a modified profile, at various overlap ratios (δ), aspect ratios (AR), and wind velocity (V). A free air jet test rig is used to carry out the experiments, while three-dimensional unsteady Reynolds-averaged Navier–Stokes (URANS) equations are used, in conjunction with the renormalization group (RNG) k–ɛ turbulence model, to perform the computations. The present experimental results successfully verify the simulation predictions obtained by the selected turbulence model. The RNG k–ɛ turbulence model has been chosen based on previous tests performed and published by the authors. Furthermore, both torque coefficient (CT) and power coefficient (CP) are numerically predicted at various tip speed ratios (λ) for overlap ratios (δ) ranging from 0.0 to 0.5, aspect ratios (AR) ranging from 0.75 to 3, and wind velocity values ranging from 4 to 18 m/s. Unlike the conventional rotor, the present twisted rotor with a modified profile produces significant performance improvement in the case of modified rotor without overlapping (δ = 0.0). Moreover, the peaks of CT and CP of the twisted rotor with the modified profile are enhanced with the increase in the aspect ratio. However, the percentage increase is noticed to be insignificant for AR greater than two. The maximum power coefficient (CPmax) for the twisted rotor with the modified profile and optimized design is 0.305 at a wind velocity of 6 m/s, with a performance gain of 75.3% compared to the conventional Savonius wind rotor which has CPmax=0.174.

Performance Improvement in a Helical Savonius Wind Rotor

Abstract: 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.

CFD Investigation of A New Elliptical-Bladed Multistage Savonius Rotors

Abstract: The Savonius -conventional wind turbine is a class of wind turbines designed with a vertical axis. It has a good starting capacity and an insensitivity to wind direction. It works relatively at low wind speed in an easy installation. Savonius wind turbine faces major drawbacks, including some of the low efficiency and high negative torque created by the returning blade. Many attempts have been undertaken to optimize the blade’s shape to increase the performance of these wind turbines. The vertical axis is still under development. The elliptical-blades with a cut angle equal 47.50° have recently shown enhanced performance. In this study, we investigate the effect of Elliptical-bladed multistage Savonius Rotors (rotor aspect ratio, stage aspect ratio) on the performance by means of numerical simulation. The results obtained by comparison of one, two, and three-stage rotors indicate that the maximum power coefficient increase with a number of the stages (for the rotors with similar RAR of 0.7). Moreover, for the rotors with similar SAR of 0.7, the two stages have the highest performance than others.

An innovative augmentation technique of savonius wind turbine performance

Abstract: 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 ...

Savonius turbine performance with slotted blades

Abstract: Non-renewable energy source will run out quickly and pollute dangerously the environment. This causes the change in using source of energy to the renewable energy which is clean and eco-friendly. Wind turbine is one of renewable energy which is eco-friendly and having abundant sources. Indonesia has wind velocity for about 4 m/s which is appropriate to be installed Savonius wind turbine. This paper aims to increase Savonius wind turbine performance by adding slotted 5 mm and 7 mm, at 30 % chord of blade. In measuring the turbine, blower fans were used as the source of wind with the wind velocity of about 4 m/s to 7 m/s. The result showed that applying slotted blades could increase torque, therefore it was able to produce performance improvement at the condition of low angular velocity. The highest power coefficient occurred when slotted blades variation 5 mm at 30 % chord of blade is 0.118 at TSR 0.350.

Experimental Investigation on a Ducted Savonius Vertical Axis Wind Turbine and its Performance Comparison with and without Endplates

Abstract: As the energy demand is growing and fossil fuel based energy resources are getting depleted, there has been an increased focus on the use of renewable energy resources. Wind energy is a highly suitable energy resource that can be harvested for the purpose. 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. The paper introduces a novel concept about a Ducted Savonius wind turbine where power generation can increase more than 10 folds. The paper provides experimental validation of the effect of using a converging ducted structure with a single stage and double stage configurations of a Savonius wind turbine. The paper also compares the turbine’s performance with and without endplates and compares Single Stage and Double Stage Turbine. The experiment results show that around 15% increase in tangential blade velocity in single stage rotor when end plates are used. The results of the study proves that power coefficient increases with the addition of a converging ducted structure with the Savonius wind turbine, and also with the use of endplates.

Design and 3D CFD Static Performance Study of a Two-Blade IceWind Turbine

Abstract: The IceWind turbine, a new type of Vertical Axis Wind Turbine, was proposed by an Iceland based startup. It is a product that has been featured in few published scientific research studies. This paper investigates the IceWind turbine’s performance numerically. Three-dimensional numerical simulations are conducted for the full scale model using the SST K-ω model at a wind speed of 15.8 m/s. The following results are documented: static torque, velocity distributions and streamlines, and pressure distribution. Comparisons with previous data are established. Additionally, comparisons with the Savonius wind turbine in the same swept area are conducted to determine how efficient the new type of turbine is. The IceWind turbine shows a similar level of performance with slightly higher static torque values. Vortices behind the IceWind turbine are confirmed to be three-dimensional and are larger than those of Savonius turbine.

Experimental Study of Savonius Wind Turbine Performance with Blade Layer Addition

Abstract: Article history: Received 22 January 2020 Received in revised form 24 February 2020 Accepted 24 February 2020 Available online 7 April 2020 Savonius, a type of vertical axis wind turbine (VAWT), is applicable for harvesting wind energy in Indonesia, having an average wind speed of 4 5 m/s. Owning the advantages as suitable for placing in the urban areas as well as reducing the huge electricity load, the Savonius received considerable attention from researchers in making the performance improvement. Therefore, the current research provides an investigation on the effect of adding extra layers on concave blades on the performance of the Savonius wind turbine model. As the novelty, the modification of conventional Savonius turbine has been developed by adding single and multiple layer blades on the tip blade with an overlap ratio (OR) of 10 and 15%. It was tested under wind speeds of 6.46, 6.99, and 7.27 m/s, which generated by the fans blower with a 2x2 configuration. The results show that the addition of multiple layers increased the Savonius power coefficient by 22.4% and 11.2% at OR of 10 and 15%, respectively. The highest power coefficient (Cp) is found at 0.12, which obtained by the Savonius turbine with multiple layers of 900 and OR of 10% configuration. It is concluded that adding the multiple layer blades enhanced the performance of Savonius wind turbines.

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

Abstract: 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.

Numerical Study of Bach-bladed Savonius Wind Turbine with Varying Blade Shape Factor

Abstract: Savonius wind turbine with Bach-profile blades is considered in this study. Previous studies have shown that a rotor with the Bach-profile blade produces better performance than a standard Savonius turbine. This study focuses on the blade shape factor variations of the Bach-profile blade to give the best performance. Two-dimensional unsteady simulations are performed with moving mesh. The configuration being tested is the Savonius rotor with Bach-profile blades with an arc angle of 135◦ . The blade shape factor is varied 0.2, 0.3, 0.4 at a constant freestream velocity of 4 m/s, with a corresponding Reynolds number of 20,000. The k-ω Shear Stress Transport turbulence model was used, with secondorder discretization schemes for the pressure and momentum equations. The boundary conditions were set as velocity inlet for the inlet, outflow for the outlet, and walls for the blade surfaces. The top and bottom sides were set as symmetric. Results showed that the configuration with a shape factor of 0.4 gave the best performance among the others. This configuration gave a higher moment coefficient and power coefficient of about 6.8% and 7.3%, respectively. Results extracted from the simulation includes the flow structure, and the distribution of the pressure coefficients along the blade surface.

Slotted blade effect on Savonius wind rotor performance

Abstract: The increasing needs for energy and the depletion sources of fossil fuels required the use of renewable and clean energy sources. Wind energy is a renewable energy that demand is high right now because it is easily obtained, abundant and environmentally friendly. Wind turbines use the available kinetic energy of the wind to be converted into mechanical and electrical energy. Savonius is vertical types of wind turbines that have advantages such as construction, low investment costs, and high-speed initial torque. However, Savonius turbines have a disadvantage of low efficiency. This research aims to improve the performance of the Savonius wind turbine by using a slotted blade. In this research, conventional Savonius rotor experiments were carried out and approved by the slotted blade by varying the slot position. Blower fans are used as a source of wind with variations in wind speed from 5.94 m / s to 7.27 m / s. The results showed that the use of a slotted blade could increase coefficient power of the Savonius turbine 0.95 with a variation of the slotted blade at 25% position and an increase of 14.4% compared to conventional Savonius turbines.

Unsteady-state numerical analysis of advanced Savonius wind turbine

Abstract: In order to improve the performance coefficients of the classic Savonius rotor, a newly-designed blade was proposed and numerically analyzed via CFD tools. For this purpose, a comprehensive-validat...

Characteristics of the Savonius Wind Turbine Using Multiple Guide Vanes

Abstract: This paper aims at identifying the characteristics of the Savonius Wind Turbine using a guide vane, which functions as the steering mechanism and reduces the negative torsion on the returning blade. The addition of the guide vane did not influence the turbine’s capacity in receiving wind direction. The number of guide vanes varied from 4, 8, and 16 with an angle of 45°. The testing was conducted in a wind tunnel at the wind speeds of 4 m/s, 5 m/s and 6 m/s. The turbine with the additional 16 guide vanes gave the best result. The static torsion increased by 84%, dynamic torsion increased by 57%, and the coefficient of power increased by 58% at the speed of 4 m/s.

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 geome...

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

Abstract: 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.

Simple Vertical Axis Wind Turbine for Low Wind Speed

Abstract: Wind energy is one of the potential renewable energy in Indonesia, however low wind speed turbine needs to be designed to adjust for available wind characteristic in the area. Vertical axis wind turbine with Savonius type is suitable for low wind speed application and in this paper turbine design has been optimized aerodynamically using computational fluid dynamics and following raw material size constraint. One-level savonius wind turbine has been designed and compared to previous work of two-lavel wind turbine. Based on CFD simulations, one-level turbine has better performance than the other one. Both wind turbines have large torque at zero RPM which indicates that they are suitable for low wind speed application.

Design Optimization of Savonius Wind Turbine Using CFD-Particle Swarm Optimization with Power Flow Validation Experimentally

Abstract: Air wheel generator or wind turbine generator has capabilities in generating electricity even at the lowest speed. Recently, the Savonius wind turbine with combined wind deflector and housing that applied at the top of car roof. In this paper, the unidirectional vertical axis wind turbine with two blades of Savonius type and belting system have been numerically optimizes using Computational-Particle Swarm Optimization (CFD-PSO). The 5-step optimization was done systematically to determine the related formulation based on the geometrical dimension of wind turbine blade and design constraints. The simplified model of the classical cantilever beam was used in formulating the bending stress and deflection as a constraint. Then the simulation analysis in Matlab was performed using Particle Swarm Optimization (PSO) method in minimization the mass of blades. The current generation was compared to the initial design OPTION 1 for the blades with a mass of 1.3414 kg. From simulation analysis results, the researcher found OPTION 3 has m3 =0.8387 kg with 37.5% mass reduction of blades. The result of OPTION 3= [0.1 0.001] with belting unit were proposed to be used in prototype development that achieving the objective in minimization the mass of blades but not fulfil the minimum power and current generated caused by the existing generator type not enough rotational speed with minimum of 1400 for cut in speed for standard automotive application.