Performance of Double Blade Savonius Rotor at Low Rotational Speed

2020 ◽  
Vol 17 (2) ◽  
pp. 729-735 ◽  
Author(s):  
Mohanad Al-Ghriybah ◽  
Mohd Fadhli Zulkafli ◽  
Djamal Hissein Didane ◽  
Sofian Mohd
Keyword(s):  
Turbulence Model ◽  
Rotational Speed ◽  
Maximum Power ◽  
Power Coefficient ◽  
Speed Ratio ◽  
Tip Speed Ratio ◽  
Savonius Rotor ◽  
Maximum Improvement ◽  
Torque Coefficient ◽  
Better Than

The performance of the single and double blade Savonius rotors are numerically analyzed using the K-ε/realizable turbulence model. The computations are implemented at different values of tipspeed ratio from 0.2 to 0.4 with a step of 0.05. Both rotors have the same dimensions with an external overlap between their blades equals 0.02 m. The results indicate that the double blade rotor performs better than the single blade rotor in terms of power coefficient. In addition, the torque coefficient is improved at all tested values of tip-speed ratio. Furthermore, the results of the simulation show that the maximum power coefficient was 0.163 at tip-speed ratio = 0.4 for the double blade rotor, whereas the maximum improvement of the double blade rotor occurs at tipspeed ratio = 0.2 with a percentage of 11.86% compared to the single blade rotor. Moreover, the highest value of the torque coefficient was 0.524 at tip-speed ratio = 0.2 for the double blade rotor.

Study on Performance and Flow Condition of a Cross-Flow Wind Turbine With a Symmetrical Casing

2011 ◽  
Vol 133 (5) ◽  
Author(s):  
Junichiro Fukutomi ◽  
Toru Shigemitsu ◽  
Hiroki Daito
Keyword(s):  
Wind Turbine ◽  
Rotational Speed ◽  
Flow Condition ◽  
Cross Flow ◽  
Low Noise ◽  
Maximum Power ◽  
Power Coefficient ◽  
Speed Ratio ◽  
Tip Speed Ratio ◽  
The Cross

A cross-flow wind turbine has a high torque coefficient at a low tip speed ratio. Therefore, it is a good candidate for use as a self-starting turbine. Furthermore, it has low noise and excellent stability; therefore, it has attracted attention from the viewpoint of applications as a small wind turbine for an urban district. However, its maximum power coefficient is extremely low (10%) as compared to that of other small wind turbines. Prevailing winds in two directions often blow in urban and coastal regions. Therefore, in order to improve the performance and the flow condition of the cross-flow rotor, a casing suitable for this sort of prevailing wind conditions is designed in this research and the effect of the casing is investigated by experimental and numerical analysis. In the experiment, a wind tunnel with a square discharge is used and main flow velocity is set as 20 m/s. A torque meter, a rotational speed pickup, and a motor are assembled with the same axis as the test wind turbine and the tip speed ratio is changeable by a rotational speed controller. The casing is set around the cross-flow rotor and flow distribution at the rotor inlet and the outlet is measured by a one-hole pitot tube. The maximum power coefficient is obtained as Cpmax = 0.19 with the casing, however Cpmax = 0.098 without the casing. It is clear that the inlet and the outlet flow condition is improved by the casing. In the present paper, in order to improve the performance of a cross-flow wind turbine, a symmetrical casing suitable for prevailing winds in two directions is proposed. Then, the performance and the internal flow condition of the cross-flow wind turbine with the casing are clarified. Furthermore, the influence of the symmetrical casing on performance is discussed and the relation between the flow condition and performance is considered.

scholarly journals Performance Analysis of a Helical Savonius Rotor with Shaft at 45° Twist Angle Using CFD

2013 ◽  
Vol 3 (1) ◽  
pp. 118 ◽  
Author(s):  
Rajat Gupta ◽  
Bachu Deb ◽  
R. D. Misra
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Twist Angle ◽  
Maximum Power ◽  
Power Coefficient ◽  
Speed Ratio ◽  
Complete Cycle ◽  
Tip Speed Ratio ◽  
Savonius Rotor ◽  
Rotor Angle

Helical Savonius rotor is considered to be superior to conventional Savonius rotor in terms of higher power coefficient (Cp) and better starting characteristic. However studies related to helical Savonius rotors is few. In view of this, in this paper, the performance of a helical Savonius rotor with shaft at 45° bucket twist angle for one complete cycle of rotation was analyzed using Computational Fluid Dynamics. A two-bucket helical Savonius rotor with shaft was designed using GAMBIT, having a height of 60 cm and diameter of 17 cm with 45° bucket twist angle. A three dimensional Computational Fluid Dynamics analysis using Fluent package was done to predict the performance of the rotor. Standard k-? turbulence model with second order upwind discretization scheme and standard wall condition was used. Grid independence test was also conducted to have the best meshing accuracy. Power coefficients (Cp) of the rotor at different tip speed ratios were evaluated for rotor angle variation from 0° to 180°. Cp at each rotor angle increased with increase of tip speed ratio up to an optimum tip speed ratio, but then decreased even if tip speed ratio was further increased. Moreover, the effect of rotor angle on Cp in a complete cycle of rotation was analyzed. Cp was found to be positive at all rotor angles, and higher values of Cp were obtained at rotor angles namely 45°, 90°, 225° and 270°, which would contribute maximum power production by the rotor. In addition to these, flow physics of the rotor was studied using tangential velocity plots w.r.t. rotor angle and path lines across the rotor. It was found that at 45°, 90° and 135° rotor angles, maximum concentration of the path lines near the tip of the blades in the upstream and downstream side of the rotor had occurred, which would be responsible for generation of maximum power coefficient in its clockwise rotation.

Improving the Energy Conversion Efficiency of a Savonius Rotor Using Automatic Valves

2019 ◽  
Vol 141 (3) ◽  
Author(s):  
M. Amiri ◽  
M. Anbarsooz
Keyword(s):  
Low Power ◽  
Energy Conversion ◽  
Conversion Efficiency ◽  
Energy Conversion Efficiency ◽  
Maximum Power ◽  
Power Coefficient ◽  
Speed Ratio ◽  
Tip Speed Ratio ◽  
Savonius Rotor ◽  
Rotor Axis

Savonius wind turbines are popular for their easy fabrication and high starting capabilities. Nevertheless, they suffer from low power coefficients, which are mainly due to a negative torque resulting from the blade moving against the upcoming wind. Numerous methods have been proposed to alleviate the negative torque, among them are modified blade profiles (twisted blades), adding flow deflectors, and valve-aided blades. In this study, the effects of adding automatic valves to a two-bladed Savonius rotor on its energy conversion efficiency are investigated numerically and experimentally. The valves are placed at three different positions: close to the rotor axis, at the blade center, and at the tip of the rotor. Results show that although adding valves can decrease the negative torque of the returning blade, they can also lead to a considerable reduction in the positive torque of the advancing blade. For the rotors in the current study, the maximum power coefficient is increased 20.8% when the valves are at the tip of the blades, while the two other cases have decreased the power coefficient of the rotor. Adding the valves to the blades does not change the tip speed ratio corresponding to the maximum power coefficient of the rotor.

scholarly journals Studi Numerik: Pengaruh Omni-Directional Guide Vane (ODGV) Terhadap Efisiensi Turbin Angin Savonius Konvensional

2020 ◽  
Vol 15 (2) ◽  
pp. 82
Author(s):  
Yoga Arob Wicaksono
Keyword(s):  
Guide Vane ◽  
Power Coefficient ◽  
Speed Ratio ◽  
Ansys Fluent ◽  
Tip Speed Ratio ◽  
S Parameter ◽  
Torque Coefficient

<p>Penelitian ini menyajikan analisa numerik pengaruh <em>Omni-Direction Guide Vane</em> (ODGV) terhadap efisiensi turbin angin Savonius konvensional. Tujuan utama dari penelitian ini adalah untuk mengembangkan desain ODGV yang dapat meningkatkan efisiensi turbin angin Savonius skala kecil. Tiga desain ODGV dengan sudut kemiringan 50<sup>o</sup>, 60<sup>o</sup>, dan 70<sup>o</sup> dianalisa menggunakan<em> </em>software ANSYS-Fluent R15<em>. </em>Simulasi dilakukan pada model 2D dengan model turbulen <em>k-ε</em> standar dan kecepatan angin konstan 6 m/s. Parameter efisiensi yang dihitung pada simulasi ini antara lain: <em>torque coefficient</em><em> </em>(<em>C</em><sub>t</sub>)<em>, power coefficient</em><em> </em>(<em>C</em><sub>p</sub>)<em>, </em>dan <em>tip speed ratio</em> (TSR). Hasil penelitian menunjukkan bahwa OGDV mampu meningkatkan efisiensi turbin angin Savonius sebesar 82%. Peningkatan tertinggi dicapai dengan menggunakan variasi ODGV dengan sudut kemiringan 50<sup>o</sup>.</p>

Experimental Study of a Pinwheel-Type Wind Turbine

2003 ◽  
Vol 27 (3) ◽  
pp. 227-236 ◽  
Author(s):  
Yasuyuki Nemoto ◽  
Izumi Ushiyama
Keyword(s):  
Experimental Study ◽  
Wind Tunnel ◽  
Wind Turbine ◽  
Optimum Design ◽  
Architectural Design ◽  
Frontal Area ◽  
Power Coefficient ◽  
Speed Ratio ◽  
Tip Speed Ratio ◽  
Torque Coefficient

Pinwheels have been familiar as toys for hundreds of years. Not only do they have an attractive appearance, they can also be fabricated from just one piece of plate. Application is possible, e.g. for education and architectural design. The purpose of this paper is to clarify the characteristics and to determine the optimum design configuration of pinwheel type wind turbines. The authors fabricated the test rotors with various shapes and carried out the experiment in a wind tunnel. As a result, the following facts were obtained: (1) Power coefficient with the traditional 4 blades has, CPmax = 0.17 at λ = 2. (2) High tip speed is obtained by cutting the frontal area of pinwheel. Tip speed ratio at no load can be easily changed from λ = 3 to 6 by changing the cutting area. Maximum power coefficient CPmax = 0.22 was obtained at tip speed ratio λ = 3.5. (3) Increased torque is obtained by cutting the edge area of the pinwheel. Tip speed ratio at no load can be easily changed from λ = 2 to 3, and torque coefficient can be easily changed from CQmax = 0.15 to 0.25, by changing the cut area.

scholarly journals Studi Eksperimen Pengaruh Jumlah Sudu Terhadap Kinerja Wind Turbine Crossflow

2021 ◽  
Vol 16 (2) ◽  
pp. 218
Author(s):  
Fahrudin Fahrudin ◽  
Fitri Wahyuni ◽  
Dini Oktavitasari
Keyword(s):  
Wind Turbine ◽  
Alternative Energy ◽  
Wind Tunnel Test ◽  
Vertical Axis ◽  
Power Coefficient ◽  
Speed Ratio ◽  
Test Scheme ◽  
Vertical Axis Wind Turbine ◽  
Tip Speed Ratio ◽  
Torque Coefficient

<p>Wind is an alternative energy that is environmentally friendly and sustainable. Therefore, we need a type of wind turbine that can receive wind from all directions. The crossflow type vertical axis wind turbine has a high torque coefficient at a low tip speed ratio. The purpose of this study was to determine the effect of the number of blades on the performance of the vertical axis crossflow wind turbine. The experimental test was carried out by varying the number of blades. The configuration is analyzed using the experimental wind tunnel test scheme which has been modified in the section test section. The results showed that the number of blades 16 has a power coefficient ( ) = 0.23 tip speed ratio (TSR) = 0.42 at a wind speed of 4 m / s.</p><p><strong><br /></strong></p>

Numerical Simulation on 2D Savonius Rotor in Ground Effect

2014 ◽  
Vol 953-954 ◽  
pp. 424-427
Author(s):  
Jian Yong Zhu ◽  
Kai Wang ◽  
Hai Bin Ruan
Keyword(s):  
Numerical Simulation ◽  
Power Output ◽  
Ground Effect ◽  
Aerodynamic Performance ◽  
Power Coefficient ◽  
Speed Ratio ◽  
Tip Speed Ratio ◽  
Savonius Rotor ◽  
Calculation Results ◽  
Torque Values

The Aerodynamic Performance of 2D Savonius Rotor in Ground Effect is Numerically Simulated through Solving Unsteady Compressible RANS Equations and the Standard k-ε Turbulence Model. the Calculation Results Indicate that the Ground Effect Influences the Starting Performance and the Power Output. the Optimal Height between the Ground to the Lowest Part of the Rotor is 0.4 Times Rotation Diameter, at which the Starting Performance is Optimal. the Ground Effect also Increases the Power Coefficient and the Tip Speed Ratio Corresponding to the Maximum Power Coefficient. when Determining the Rated Tip Speed Ratio, the Fluctuation of the Torque Values and the Power Coefficient with Different Tip Speed Ratio should be Synthesized.

scholarly journals PERFORMANCE ANALYSIS OF A HELICAL SAVONIUS ROTOR WITHOUT SHAFT AT 45° TWIST ANGLE USING CFD

2013 ◽  
pp. 126-133 ◽  
Author(s):  
Bachu Deb ◽  
Rajat Gupta ◽  
R.D. Misra
Keyword(s):  
Twist Angle ◽  
Three Dimensional ◽  
Power Coefficient ◽  
Speed Ratio ◽  
Complete Cycle ◽  
Tip Speed Ratio ◽  
Savonius Rotor ◽  
Velocity Magnitude ◽  
Computational Fluid Dynamics Analysis ◽  
Upwind Discretization

Helical Savonius rotor exhibits better performance characteristics at all the rotor angles compared to conventional Savonius rotor. However studies related to the performance measurement and flow physics of such rotor are very scarce. Keeping this in view, in this paper, a three dimensional Computational Fluid Dynamics analysis using commercial Fluent 6.2 software was done to predict the performance of a two-bucket helical Savonius rotor without shaft and with end plates in a complete cycle of rotation. A two-bucket helical Savonius rotor having height of 60 cm and diameter of 17 cm with 45° bucket twist angle was designed using Gambit. The buckets were connected at the top and bottom circular end plates, which are 1.1 times the rotor diameter. The k-ε turbulence model with second order upwind discretization scheme was adopted with standard wall condition. Power coefficients (Cp) and torque coefficients (Ct) at different tip speed ratios were evaluated at different rotor angles. From the investigation, it was observed that power coefficient increased with increase of tip speed ratio up to an optimum limit, but then decreased even further tip speed ratio was increased. Further investigation was done on the variations of Cp & Ct in a complete cycle of rotation from 0° to 360° in a step of 45° rotor corresponding to the optimum tip speed ratio. The value of Cp at all the rotor angles is positive. Moreover, velocity magnitude contours were analyzed for each rotor angle and it could be concluded that high aerodynamic torque and power can be expected when the rotor is positioned at 45º & 90º with respect to incoming flow.

scholarly journals Performance assessment and optimization of a helical Savonius wind turbine by modifying the Bach’s section

2021 ◽  
Vol 3 (8) ◽  
Author(s):  
M. Niyat Zadeh ◽  
M. Pourfallah ◽  
S. Safari Sabet ◽  
M. Gholinia ◽  
S. Mouloodi ◽  
...  
Keyword(s):  
Wind Turbine ◽  
Performance Assessment ◽  
Turbulent Flows ◽  
Power Coefficient ◽  
Speed Ratio ◽  
Tip Speed Ratio ◽  
Basic Model ◽  
Turbine Performance ◽  
Primary Model ◽  
Savonius Wind Turbine

AbstractIn this paper, we attempted to measure the effect of Bach’s section, which presents a high-power coefficient in the standard Savonius model, on the performance of the helical Savonius wind turbine, by observing the parameters affecting turbine performance. Assessment methods based on the tip speed ratio, torque variation, flow field characterizations, and the power coefficient are performed. The present issue was stimulated using the turbulence model SST (k- ω) at 6, 8, and 10 m/s wind flow velocities via COMSOL software. Numerical simulation was validated employing previous articles. Outputs demonstrate that Bach-primary and Bach-developed wind turbine models have less flow separation at the spoke-end than the simple helical Savonius model, ultimately improving wind turbines’ total performance and reducing spoke-dynamic loads. Compared with the basic model, the Bach-developed model shows an 18.3% performance improvement in the maximum power coefficient. Bach’s primary model also offers a 12.4% increase in power production than the initial model’s best performance. Furthermore, the results indicate that changing the geometric parameters of the Bach model at high velocities (in turbulent flows) does not significantly affect improving performance.

Sign in / Sign up

Export Citation Format

Share Document