scholarly journals Investigations on the Effect of Radius Rotor in Combined Darrieus-Savonius Wind Turbine

2018 ◽  
Vol 2018 ◽  
pp. 1-7 ◽  
Author(s):  
Kaprawi Sahim ◽  
Dyos Santoso ◽  
Dewi Puspitasari
Keyword(s):  
Wind Turbine ◽  
Wind Tunnel Test ◽  
Vertical Axis ◽  
Radius Ratio ◽  
Small Scale ◽  
Wind Speeds ◽  
Vertical Axis Wind Turbines ◽  
Savonius Wind Turbine ◽  
Darrieus Rotor ◽  
Low Wind Speeds

Renewable sources of energy, abundant in availability, are needed to be exploited with adaptable technology. For wind energy, the wind turbine is very well adapted to generate electricity. Among the different typologies, small scale Vertical Axis Wind Turbines (VAWT) present the greatest potential for off-grid power generation at low wind speeds. The combined Darrieus-Savonius wind turbine is intended to enhance the performance of the Darrieus rotor in low speed. In combined turbine, the Savonius buckets are always attached at the rotor shaft and the Darrieus blades are installed far from the shaft which have arm attaching to the shaft. A simple combined turbine offers two rotors on the same shaft. The combined turbine that consists of two Darrieus and Savonius blades was tested in wind tunnel test section with constant wind velocity and its performance was assessed in terms of power and torque coefficients. The study gives the effect of the radius ratio between Savonius and Darrieus rotor on the performance of the turbine. The results show that there is a significant influence on the turbine performance if the radius ratio was changed.

scholarly journals Effect of Concentrator, Blade Diameter and Blade Number on the Savonius Wind Turbine Performance

2017 ◽  
Vol 5 (2) ◽  
Author(s):  
Ida Bagus Alit ◽  
Rudy Sutanto ◽  
I Made Mara ◽  
Mirmanto Mirmanto
Keyword(s):  
Wind Turbine ◽  
Concentration Ratio ◽  
Turbine Blades ◽  
Vertical Axis ◽  
Power Coefficient ◽  
Wind Speeds ◽  
Vertical Axis Wind Turbines ◽  
Negative Moment ◽  
Low Efficiency ◽  
Low Wind Speeds

Savonius turbine is a type of vertical-axis wind turbines. The turbine has a potential to be developed as it has a simple construction and is suitable for low wind speeds. However, the turbine is still rarely used because of the low efficiency of the turbine compared to other turbines. The low efficiency of the turbine is due to the negative moment. Some efforts have been done to reduce the negative moment such as by adding a wind concentrator. The wind concentrator can steer the incoming wind toward the turbine blades that generate positive moments, consequently, the generated power increases. The aim of this research is to determine the effect of the number and diameter of the Savonius blade wind turbine with an additional concentrator. The concentrator had a concentration ratio of 6:1 and it was tested at the lower wind speeds of 2-5 m/s. The result shows that adding a wind concentrator can increase the rotational speed of the rotor, power coefficient, and the turbine power. The Savonius turbine with two blades has the best performance compared to the three and four blades. The Savonius blade wind turbine with the rotor diameter of 12 cm is the best Savonius turbine for the concentration ratio of 6:1.

Experimental and Numerical Investigations on Drag and Torque Characteristics of Three-Bladed Savonius Wind Turbine

2009 ◽  
Author(s):  
Mosfequr Rahman ◽  
Khandakar N. Morshed ◽  
Jeffery Lewis ◽  
Mark Fuller
Keyword(s):  
Wind Turbine ◽  
Wind Turbines ◽  
Vertical Axis ◽  
The United States ◽  
Small Scale ◽  
Horizontal Axis Wind Turbine ◽  
Drag Coefficients ◽  
Vertical Axis Wind Turbines ◽  
Torque Coefficient ◽  
Savonius Wind Turbine

With the growing demand of energy worldwide, conventional energy is becoming more and more scarce and expensive. The United States is already facing an energy crunch as the fuel price soars. Therefore, there is an obvious need for alternative sources of energy—perhaps more than ever. Wind is among the most popular and fastest-growing forms of electricity generation in the world, which is pollution free and available almost at any time of the day, especially in the coastal regions. The main attraction of the vertical-axis wind turbine is its manufacturing simplicity compared to that of the horizontal-axis wind turbine. Among all different vertical axis wind turbines, Savonius wind turbine is the simplest one. Operation of the Savonius wind turbine is based on the difference of the drag force on its semi-spherical blades, depending on whether the wind is striking the convex or the concave part of the blades. The advantage of this type of wind turbine is its good self-starting and wind directional independence characteristic. It, however, has a relatively lower efficiency in comparison with the lift type vertical-axis wind turbines. Due to its simple design and low construction cost, Savonius rotors are primarily used for water pumping and wind power on a small scale. The main objective of this ongoing research work is to improve the aerodynamic performance of vertical axis Savonius wind turbine. Wind tunnel investigation has been performed on aerodynamic characteristics, such as drag coefficients, and static torque coefficient of three-bladed Savonius rotor model. Also the computational fluid dynamics (CFD) simulation has been performed using FLUENT software to analyze the static rotor aerodynamics such as drag coefficients and torque coefficient, and these results are compared with the corresponding experimental results for verification.

scholarly journals Canard optimization for enhancing the performance of small horizontal axis wind turbine at low wind speeds

2020 ◽  
Vol 37 ◽  
pp. 63-71
Author(s):  
Yui-Chuin Shiah ◽  
Chia Hsiang Chang ◽  
Yu-Jen Chen ◽  
Ankam Vinod Kumar Reddy
Keyword(s):  
Wind Turbine ◽  
Urban Areas ◽  
Horizontal Axis ◽  
Power Coefficient ◽  
Peak Performance ◽  
Small Scale ◽  
Horizontal Axis Wind Turbine ◽  
Wind Speeds ◽  
Optimum Parameters ◽  
Low Wind Speeds

ABSTRACT Generally, the environmental wind speeds in urban areas are relatively low due to clustered buildings. At low wind speeds, an aerodynamic stall occurs near the blade roots of a horizontal axis wind turbine (HAWT), leading to decay of the power coefficient. The research targets to design canards with optimal parameters for a small-scale HAWT system operated at variable rotational speeds. The design was to enhance the performance by delaying the aerodynamic stall near blade roots of the HAWT to be operated at low wind speeds. For the optimal design of canards, flow fields of the sample blades with and without canards were both simulated and compared with the experimental data. With the verification of our simulations, Taguchi analyses were performed to seek the optimum parameters of canards. This study revealed that the peak performance of the optimized canard system operated at 540 rpm might be improved by ∼35%.

Effect of Slotted Angle on Savonius Wind Turbine Performance

2021 ◽  
Vol 104 ◽  
pp. 83-88
Author(s):  
Rahmat Wahyudi ◽  
Diniar Mungil Kurniawati ◽  
Alfian Djafar
Keyword(s):  
Wind Energy ◽  
Wind Turbine ◽  
Wind Turbines ◽  
Electrical Energy ◽  
Speed Ratio ◽  
Angle Variation ◽  
Wind Speeds ◽  
Turbine Performance ◽  
Savonius Wind Turbine ◽  
Low Wind Speeds

The potential of wind energy is very abundant but its utilization is still low. The effort to utilize wind energy is to utilize wind energy into electrical energy using wind turbines. Savonius wind turbines have a very simple shape and construction, are inexpensive, and can be used at low wind speeds. This research aims to determine the effect of the slot angle on the slotted blades configuration on the performance produced by Savonius wind turbines. Slot angle variations used are 5o ,10o , and 15o with slotted blades 30% at wind speeds of 2,23 m/s to 4,7 m/s using wind tunnel. The result showed that a small slot angle variation of 5o produced better wind turbine performance compared to a standard blade at low wind speeds and a low tip speed ratio.

A Performance Comparison of Three Micro-Sized Blade Rotor Designs for Malaysia Wind Speed Condition

2015 ◽  
Vol 785 ◽  
pp. 310-314 ◽  
Author(s):  
Norzanah Rosmin ◽  
N.A. Rahman ◽  
A.H. Mustaamal
Keyword(s):  
Electrical Power ◽  
Vertical Axis ◽  
Performance Comparison ◽  
Power Coefficient ◽  
Small Scale ◽  
Experimental Setup ◽  
Wind Speeds ◽  
Vertical Axis Wind Turbines ◽  
Speed Up ◽  
Electrical Generation

Vertical-Axis Wind Turbines (VAWTs) are known as the most suitable wind turbine for small-scale electrical generation. There are many types of VAWTs and each of it has different performances and efficiency. In this work, three types of VAWT systems (Savo-B2, Savo-B4 and Giro-B3) were designed, constructed and tested to investigate the amount of electrical power that could be generated under several constant wind speeds. The blade rotors were designed and built using 2 mm thickness of aluminum plate. The tip speed ratios, power coefficients, blade rotations for each blade rotor and the simplicity of the proposed designs were studied via an experimental setup. The experimental work demonstrates that Savo-B2 provides the highest power coefficient which is up to 0.32. Meanwhile, Giro-B3 offers the fastest rotational blade speed, up to 20.53 rad/s, among the three designs.

scholarly journals Analysis of the Patent of a Protective Cover for Vertical-Axis Wind Turbines (VAWTs): Simulations of Wind Flow

2020 ◽  
Vol 12 (18) ◽  
pp. 7818
Author(s):  
Jose Alberto Moleón Baca ◽  
Antonio Jesús Expósito González ◽  
Candido Gutiérrez Montes
Keyword(s):  
Wind Speed ◽  
Wind Turbine ◽  
Wind Turbines ◽  
High Speed ◽  
Experimental Tests ◽  
Weather Conditions ◽  
Vertical Axis ◽  
Good Alternative ◽  
Wind Speeds ◽  
Vertical Axis Wind Turbines

This paper presents a numerical and experimental analysis of the patent of a device to be used in vertical-axis wind turbines (VAWTs) under extreme wind conditions. The device consists of two hemispheres interconnected by a set of conveniently implemented variable section ducts through which the wind circulates to the blades. Furthermore, the design of the cross-section of the ducts allows the control of the wind speed inside the device. These ducts are intended to work as diffusers or nozzles, depending on the needs of the installation site. Simulations were performed for the case of high-speed external wind, for which the ducts act as diffusers to reduce wind speed and maintain a well-functioning internal turbine. Four different patent designs were analyzed, focusing on turbine performance and generated power. The results indicate that the patent allows the generation of electric power for a greater range of wind speeds than with a normal wind turbine. The results support that this patent may be a good alternative for wind power generation in geographic areas with extreme weather conditions or with maintained or strong gusty wind. Experimental tests were carried out on the movement of the blades using the available model. Finally, the power curve of the model of this wind turbine was obtained.

scholarly journals Numerical Investigations of the Effects of the Rotating Shaft and Optimization of Urban Vertical Axis Wind Turbines

Energies ◽  
2018 ◽  
Vol 11 (7) ◽  
pp. 1870 ◽  
Author(s):  
Lidong Zhang ◽  
Kaiqi Zhu ◽  
Junwei Zhong ◽  
Ling Zhang ◽  
Tieliu Jiang ◽  
...  
Keyword(s):  
Wind Turbine ◽  
Wind Turbines ◽  
Suction Side ◽  
Vertical Axis ◽  
Power Coefficient ◽  
Small Scale ◽  
Physical Parameters ◽  
Rotating Shaft ◽  
Vertical Axis Wind Turbines ◽  
Negative Effect

The central shaft is an important and indispensable part of a small scale urban vertical axis wind turbines (VAWTs). Normally, it is often operated at the same angular velocity as the wind turbine. The shedding vortices released by the rotating shaft have a negative effect on the blades passing the wake of the wind shaft. The objective of this study is to explore the influence of the wake of rotating shaft on the performance of the VAWT under different operational and physical parameters. The results show that when the ratio of the shaft diameter to the wind turbine diameter (α) is 9%, the power loss of the wind turbine in one revolution increases from 0% to 25% relative to that of no-shaft wind turbine (this is a numerical experiment for which the shaft of the VAWT is removed in order to study the interactions between the shaft and blade). When the downstream blades pass through the wake of the shaft, the pressure gradient of the suction side and pressure side is changed, and an adverse effect is also exerted on the lift generation in the blades. In addition, α = 5% is a critical value for the rotating shaft wind turbine (the lift-drag ratio trend of the shaft changes differently). In order to figure out the impacts of four factors; namely, tip speed ratios (TSRs), α, turbulence intensity (TI), and the relative surface roughness value (ks/ds) on the performance of a VAWT system, the Taguchi method is employed in this study. The influence strength order of these factors is featured by TSRs > ks/ds > α > TI. Furthermore, within the range we have analyzed in this study, the optimal power coefficient (Cp) occurred under the condition of TSR = 4, α = 5%, ks/ds = 1 × 10−2, and TI = 8%.

scholarly journals Modified Design of Savonius Wind Turbine Blade for Performance Improvement

2019 ◽  
Vol 9 (1) ◽  
pp. 1432-1437
Keyword(s):  
Wind Turbine ◽  
Wind Turbines ◽  
New Technologies ◽  
Vertical Axis ◽  
Horizontal Axis ◽  
Wind Speeds ◽  
Wind Potential ◽  
Horizontal Axis Wind Turbines ◽  
Savonius Wind Turbine ◽  
Low Performance

In the context of worldwide energetic transition, wind energy shows up as one of the most prominent renewable energy to provide an alternative for the conventional energy source. Therefore, new technologies of a wind turbine are developed, horizontal axis wind turbines have been extensively investigated and evolved. However, the development of vertical axis wind turbines is still an open and area of research, The main objective is to develop a more efficient type of wind turbines able to operate at low wind speeds to take hold maximum wind potential, The Savonius rotor goes with such conditions, however, it faces critical drawbacks, in particular, the low performance in comparison with horizontal axis wind turbines, as well, the blade in return of savonius wind turbine generates a negative torque leading to a decrement of turbine performance. The present work aims to investigate a modified model of the conventional Savonius rotors with a focus on improving the coefficient of power, transient computational fluid dynamics (CFD) simulations are carried out in an effort to perform a validation of numerical results according to experimental data, also to conduct a comparative analysis of both savonius models

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