Effect of Savonius blade height on the performance of a hybrid Darrieus-Savonius wind turbine

A vertical hybrid turbine commonly consists of a Darrieus and Savonius rotor where the Savonius is inside Darrieus turbine. This paper describes the experimental study of hybrid Darrieus-Savonius wind turbines by variation in Savonius blade height. In this case, the effect of the blade height of the Savonius blade was studied experimentally in a subsonic wind tunnel. The effect of the height of a Savonius blade relative to that of Darrieus called blade height ratios δ was investigated to know the hybrid turbine performance. The performance is represented by power and torque coefficient. The result shows that the hybrid turbine with height ratio greater than unity δ = 1.4 gives the highest power CP = 0.20 and torque coefficient CT = 0.129. It is investigated that the torque and the power coefficient have a higher value than that of Darrieus turbine, in which the increase in power and torque coefficient are 48% and 29%, respectively. This hybrid wind turbine with a blade height ratio greater than unity can be considered as an important variable in the wind turbine construction.

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

SN Applied Sciences ◽

10.1007/s42452-021-04731-0 ◽

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.

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Effect of Stator Vane on the Performance of the Savonius Wind Turbine

R E M (Rekayasa Energi Manufaktur) Jurnal ◽

10.21070/r.e.m.v4i2.811 ◽

2019 ◽

Vol 4 (2) ◽

pp. 159-168

Author(s):

Yoga Arob Wicaksono

Keyword(s):

Wind Turbine ◽

Performance Testing ◽

Turbine Rotor ◽

Power Coefficient ◽

Speed Ratio ◽

Stator Vane ◽

Torque Coefficient ◽

Savonius Wind Turbine ◽

Air Speed ◽

Turbulent Air Flow

The turbulent air flow conditions in the urban area have a large effect on the performance of Savonius rotor wind turbines. To overcome this problem, a new design of the stator vane needs to be made. the stator vane has the ability to direct wind to the turbine rotor and increase air speed by utilizing throttling effects. Thus, the performance of the Savonius wind turbine can increase. In this study, the Savonius type vertical wind turbine is configured with three stator vane designs that have slope angles: 60o, and 70o. Performance testing is carried out at angles: 0o, 30o, and 60o towards the midpoint of the stator vane to find the direction of direction coming from the best wind on each stator vane design. All configurations are analyzed using an experimental wind tunnel open testing scheme with a wind speed range of 3-5 m/s. The parameters produced from the experiment include: power coefficient (Cp), torque coefficient (Ct) and Tip Speed Ratio (TSR). The results showed that the stator vane with 60o inclination angle was able to increase Cp 35.66% in the 60o incoming wind direction.

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Optimization of Two and Three Rotor Savonius Wind Turbine

Volume 9: Oil and Gas Applications; Supercritical CO2 Power Cycles; Wind Energy ◽

10.1115/gt2015-43988 ◽

2015 ◽

Cited By ~ 2

Author(s):

Ahmed M. Baz ◽

Nabil A. Mahmoud ◽

Ashraf M. Hamed ◽

Khaled M. Youssef

Keyword(s):

Wind Turbine ◽

Average Power ◽

Power Coefficient ◽

Speed Ratio ◽

Rotor Design ◽

Aerodynamic Interaction ◽

Torque Coefficient ◽

Savonius Wind Turbine ◽

Improved Performance ◽

Turbine Design

The present work investigates the performance of Savonius wind turbine using two or three rotors. The new turbine design was found to have higher power coefficient compared with single rotor design. The peak average power coefficient of the three rotors was computed to be 50% higher than that of the single rotor design. The torque coefficient was also higher than that of the single rotor turbine at high tip speed ratio. This improved performance is attributed to the favorable aerodynamic interaction between the rotors which accelerates the flow around the rotors and generates higher turning torque in the direction of rotation for each rotor. The optimized arrangement of rotors showed that the upstream rotor and one downstream rotor should have a similar direction of rotation while the second downstream rotor is rotating in opposite direction.

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Numerical Modelling of Savonius Wind Turbine With Downstream Baffle

Volume 9: Oil and Gas Applications; Supercritical CO2 Power Cycles; Wind Energy ◽

10.1115/gt2015-43992 ◽

2015 ◽

Cited By ~ 1

Author(s):

Ahmed M. El Baz ◽

Nabil A. Mahmoud ◽

Ashraf M. Hamed ◽

Ahmed M. El Kholy

Keyword(s):

Wind Turbine ◽

Vertical Axis ◽

Power Coefficient ◽

Speed Ratio ◽

Vertical Axis Wind Turbine ◽

Dynamics Model ◽

Small Power ◽

Turbine Performance ◽

Savonius Wind Turbine ◽

Driving Torque

The application of small power wind turbines has been widely spreading over the last decade. The vertical axis wind turbine type is one class which is very attractive in this respect. However, due to its lower performance, it has not been extensively used in such application. The objective of the present paper is to investigate methods of Savonius turbine performance improvement. It is suggested to use a downstream baffle to achieve this goal. The baffle position, length and inclination angle are optimized using 2D Computational Fluid Dynamics model. The model is initially validated by comparison to experimental data reported for the Savonius turbine without baffle. The results show that 40–50% improvement in turbine performance can be obtained by using the optimum baffle design, compared to the turbine performance without baffle. The baffle effect is analyzed and results show that its major role is to reduce the pressure on the backside of the advancing blade. This effect enhances the positive driving torque on the advancing blade of the Savonius turbine and thus increases its power coefficient near the optimum tip speed ratio.

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An innovative augmentation technique of savonius wind turbine performance

Wind Engineering ◽

10.1177/0309524x19849860 ◽

2019 ◽

Vol 44 (1) ◽

pp. 93-112 ◽

Cited By ~ 1

Author(s):

Khaled M Youssef ◽

Ahmed M El Kholy ◽

Ashraf M Hamed ◽

Nabil A Mahmoud ◽

Ahmed M El Baz ◽

...

Keyword(s):

Wind Turbine ◽

Peak Power ◽

Stokes Equations ◽

Power Coefficient ◽

Navier Stokes ◽

Future Application ◽

Speed Ratio ◽

Ansys Fluent ◽

Turbine Performance ◽

Savonius Wind Turbine

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.

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Effect of Slotted Angle on Savonius Wind Turbine Performance

Advances in Science and Technology ◽

10.4028/www.scientific.net/ast.104.83 ◽

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.

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

Journal of Physics Conference Series ◽

10.1088/1742-6596/1477/5/052010 ◽

2020 ◽

Vol 1477 ◽

pp. 052010

Author(s):

A Subekti ◽

PA Setiawan ◽

Bachtiar ◽

N Ariwiyono ◽

B Prasojo ◽

...

Keyword(s):

Wind Turbine ◽

Numerical Study ◽

Single Cylinder ◽

Turbine Performance ◽

Savonius Wind Turbine

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Four Decades of Research Into the Augmentation Techniques of Savonius Wind Turbine Rotor

Journal of Energy Resources Technology ◽

10.1115/1.4038785 ◽

2018 ◽

Vol 140 (5) ◽

Cited By ~ 22

Author(s):

Nur Alom ◽

Ujjwal K. Saha

Keyword(s):

Wind Turbine ◽

Turbine Rotor ◽

Power Coefficient ◽

Major Drawback ◽

High Rotational Speed ◽

Savonius Rotor ◽

Augmentation Techniques ◽

Savonius Wind Turbine ◽

Low Efficiency ◽

Wind Turbine Rotor

The design and development of wind turbines is increasing throughout the world to offer electricity without paying much to the global warming. The Savonius wind turbine rotor, or simply the Savonius rotor, is a drag-based device that has a relatively low efficiency. A high negative torque produced by the returning blade is a major drawback of this rotor. Despite having a low efficiency, its design simplicity, low cost, easy installation, good starting ability, relatively low operating speed, and independency to wind direction are its main rewards. With the goal of improving its power coefficient (CP), a considerable amount of investigation has been reported in the past few decades, where various design modifications are made by altering the influencing parameters. Concurrently, various augmentation techniques have also been used to improve the rotor performance. Such augmenters reduce the negative torque and improve the self-starting capability while maintaining a high rotational speed of the rotor. The CP of the conventional Savonius rotors lie in the range of 0.12–0.18, however, with the use of augmenters, it can reach up to 0.52 with added design complexity. This paper attempts to give an overview of the various augmentation techniques used in Savonius rotor over the last four decades. Some of the key findings with the use of these techniques have been addressed and makes an attempt to highlight the future direction of research.

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Effect of Flow Inclination on Wind Turbine Performance

Journal of Engineering for Gas Turbines and Power ◽

10.1115/1.4007323 ◽

2012 ◽

Vol 134 (12) ◽

Cited By ~ 10

Author(s):

Christina Tsalicoglou ◽

Sarah Barber ◽

Ndaona Chokani ◽

Reza S. Abhari

Keyword(s):

Wind Turbine ◽

Wind Turbines ◽

Complex Terrain ◽

Wake Flow ◽

Test Facility ◽

Power Coefficient ◽

Incoming Flow ◽

Turbine Performance ◽

The Impact ◽

Blade Element

This work examines the effect of flow inclination on the performance of a stand-alone wind turbine and of wind turbines operating in the wakes of upstream turbines. The experimental portion of this work, which includes performance and flowfield measurements, is conducted in the ETH dynamically-scaled wind turbine test facility, with a wind turbine model that can be inclined relative to the incoming flow. The performance of the wind turbine is measured with an in-line torquemeter, and a 5-hole steady-state probe is used to detail the inflow and wake flow of the turbine. Measurements show that over a range of tip-speed ratios of 4–7.5, the power coefficient of a wind turbine with an incoming flow of 15 deg inclination decreases on average by 7% relative to the power coefficient of a wind turbine with a noninclined incoming flow. Flowfield measurements show that the wake of a turbine with an inclined incoming flow is deflected; the deflection angle is approximately 6 deg for an incoming flow with 15 deg inclination. The measured wake profiles are used as inflow profiles for a blade element momentum code in order to quantify the impact of flow inclination on the performance of downstream wind turbines. In comparison to the case without inclination in the incoming flow, the combined power output of two aligned turbines with incoming inclined flow decreases by 1%, showing that flow inclination in complex terrain does not significantly reduce the energy production.

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