Showing papers on "Savonius wind turbine published in 2015"

Computational Fluid Dynamics Prediction of a Modified Savonius Wind Turbine with Novel Blade Shapes

Abstract: The Savonius wind turbine is a type of vertical axis wind turbine (VAWTs) that is simply composed of two or three arc-type blades which can generate power even under poor wind conditions. A modified Savonius wind turbine with novel blade shapes is introduced with the aim of increasing the power coefficient of the turbine. The effect of blade fullness, which is a main shape parameter of the blade, on the power production of a two-bladed Savonius wind turbine is investigated using transient computational fluid dynamics (CFD). Simulations are based on the Reynolds Averaged Navier-Stokes (RANS) equations with a renormalization group turbulent model. This numerical method is validated with existing experimental data and then utilized to quantify the performance of design variants. Results quantify the relationship between blade fullness and turbine performance with a blade fullness of 1 resulting in the highest coefficient of power, 0.2573. This power coefficient is 10.98% higher than a conventional Savonius turbine.

Effect of the blade arc angle on the performance of a Savonius wind turbine

Abstract: Savonius wind turbine is a common vertical axis wind turbine which simply comprises two or three arc-type blades and can generate power under poor wind conditions. With the aim of increasing the turbine’s power efficiency, the effect of the blade arc angle on the performance of a typical two-bladed Savonius wind turbine is investigated with a transient computational fluid dynamics method. Simulations were based on the Reynolds Averaged Navier–Stokes equations, and the renormalization group k−e turbulent model was utilized. The numerical method was validated with existing experimental data. The results indicate that the turbine with a blade arc angle of 160∘ generates the maximum power coefficient, 0.2836, which is 8.37% higher than that from a conventional Savonius turbine.

Computational assessment of the influence of the overlap ratio on the power characteristics of a Classical Savonius wind turbine

Abstract: Abstract An influence of the overlap on the performance of the Classical Savonius wind turbine was investigated. Unsteady two-dimensional numerical simulations were carried out for a wide range of overlap ratios. For selected configurations computation quality was verified by comparison with three-dimensional simulations and the wind tunnel experimental data available in literature. A satisfactory agreement was achieved. Power characteristics were determined for all the investigated overlap ratios for selected tip speed ratios. Obtained results indicate that the maximum device performance is achieved for the buckets overlap ratio close to 0.

A New Design Of Savonius Wind Turbine: Numerical Study

Abstract: This paper discusses numerically a modified Savonius wind rotor focusing on the averaged torque and power coefficients over a complete cycle of operation. The numerical study is performed using the commercial software Fluent 6.3.26 with four different turbulence models. The computations are tested against available experimental data to choose the suitable turbulence model and hence to extend the numerical investigation. A modification process of the Savonius rot or blades is designed by determining nine points on the perimeter of the blade. The two points at the ends of the blade are fixed in the same locations and the other seven points are moving to different locations to generate four polynomials shapes. V shape blade rotor with three different V - angles is also studied in this paper. The influence of the rotor blade modification is checked based on the torque and power coefficients, keeping the Reynolds number, based on rotor diameter constant. The results obtained for the classical Savonius rotor are in agreement with the published experimental data, indicated that the method can be successfully used for such analysis. The theoretical results indicate that one of the polynomial blade shape has the best perfo rmance.

Investigation of the Aerodynamics of an Innovative Vertical-Axis Wind Turbine

Abstract: This paper presents the results of an experimental investigation and a three dimensional numerical analysis of the transient aerodynamic phenomena occurring in the innovative modification of classic Savonius wind turbine. An attempt to explain the increased efficiency of the innovative design a comparison with the traditional solution is undertaken. A vorticity measure based on the integral of the velocity gradient tensor second invariant is proposed in order to evaluate and compare designs. The discussed criterion is related to the vortex structures and energy dissipation. These structures are generated by the rotor and may affect the efficiency.

Optimization of Two and Three Rotor Savonius Wind Turbine

Abstract: 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 directionCopyright © 2015 by ASME

Effects of flow parameters on the performance of vertical axis swirling type Savonius wind turbine

Abstract: Wind tunnel experiments were carried out on a geometrically optimal swirling Savonius turbine by varying flow parameters to determine their effects on power and torque coefficients. The optimum geometrical configuration used in this experiment was adopted from an earlier study that features 0.20 blade overlap ratio, 195˚ blade arc angle, and 1.06 rotor aspect ratio of a 320 mm diameter rotor with closed top end plate. The parameters considered in this experimental are the hot air temperature, hot air mass flow rate, hot air inlet diameter of swirl chamber, and the free-stream wind velocity. The results indicate that higher hot air temperature and hot air mass flow rate promotes performance of the turbine while power coefficient reached maximum at a certain hot air inlet diameter. Tests on the optimum geometry at four wind velocities revealed that power coefficients are higher in higher wind velocities.

Robust Design of Savonius Wind Turbine

Abstract: The Savonius wind turbine, a class of vertical axis wind turbine (VAWT), is simple and provides a better cost-benefit ratio. It works on the principle of differential drag and is effective in rooftop and ground mounting. Despite the advantages of Savonius wind rotors, they are not preferred due to their low aerodynamic performance levels. In order to address this, several experimental and numerical studies have been carried out in recent years. The primary aim of this work is to provide a simple methodology for the robust optimal design of the Savonius wind turbine. In the parameter design stage, the performance of the turbine is maximized using the traditional Taguchi method. An L27 orthogonal array is used considering five factors of three levels each, which affect C p . Wind speed is considered to be the noise factor. Signal-noise ratio (SNR) metric is used to find the optimal settings for robust design. The aerodynamic performance of the turbine is investigated through dynamic computational fluid dynamics (CFD) models of the design sets. The numerical models used for the simulations are also discussed.

Numerical Modelling of Savonius Wind Turbine With Downstream Baffle

Abstract: 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.Copyright © 2015 by ASME

Modal Analysis of a Small Savonius Aerogenerator by Using SolidWorks Simulation

Abstract: Wind energy generation using Savonius wind turbine becomes a promising technology of renewable energy and sustainable development, opportune in urban areas for several applications. This strong rotary machine handles with high wind speeds, requires low maintenance owing to the self-lubricating bearings, and to the self-placing to the wind flow as well as to the self-starting at very low wind velocity. During last decade, the industrial computer codes become a major technology tools in modeling, and simulation of dynamics structures for improving and optimizing their performances. Present paper, investigated the dynamic comportment of a small three-bladed Savonius-aerogenerator using SolidWorks simulation software. The simulation results showed that the design reliability and stability were confirmed since no resonance to be happened in the structure and the quality factor is close to 7 for the first five vibration modes. The two first natural frequencies 16.62Hz and 16.74Hz of the wind turbine are far away from external excited frequencies active at the wind speeds up to 15m/s.

Numerical study of flow through a Savonius wind turbine

Abstract: The main objective is intended to be the numerical investigation to determine the structure of the real flow in a fixed Savonius wind turbine. A secondary objective of this numerical study will be to obtain the aerodynamic performance of studied wind turbine and also information about velocity field around the rotor.

A Study of the Influence of Guide Vane Design to Increase Savonius Wind Turbine Performance

Abstract: This work experimentally studied the influence of guide vane design to increase Savonius rotor performance. Guide vane is one of additional device that its function is for directing wind stream on to concave blade and deserves as obstacle of the wind that flowing on to convex blade. That way increased wind speeds to the rotor, consequently it produced higher power coefficient and the Savonius rotor performed better performance. Four designs of guide vane were arranged in this study. They are basic design of guide vane and basic design of guide vane that added a tilt angle on the top and bottom sides by 15°, 30°, and 45°. The result concludes that guide vane affects the performance of Savonius rotor. The power that generated by the rotor with guide vanes increase significantly compared with Savonius rotor without guide vane. The maximum improvement was attained up to 65.89%.

Experimental study of flow through a Savonius wind turbine

Abstract: The main objective is intended to be the experimental investigation in wind tunnel to determine the structure of the real flow in a fixed Savonius wind turbine. A secondary objective of this experimental study will be to obtain the aerodynamic performance of studied wind turbine and also information about velocity field around the rotor.

Design and Testing of a Low Cost and Higher Efficient Savonius Wind Turbine's Rotor Blade for Low Wind Speed Applications

Abstract: Studies indicate that vertical axis wind turbines provide a more reliable energy conversion technology as compared to horizontal axis wind turbines, especially in areas of lowly rated and/or uncertain wind speeds. The challenge however is the development of an efficient Savonius rotor blade which is affordable to low income earners in Kenya. The different technical designs available in the local market were studied and their effects in terms of noise, shadows and impacts on birds and wildlife analyzed. The objectives of this research were thus to design and develop a Savonius rotor blade with locally available materials and compare its performance and production cost with the existing blades. The blades were made using glass reinforced fibre because of the material's light weight. This factor enabled the rotor to rotate at very low wind speeds, it is also long lasting and does not rot hence can survive in all weather conditions. A prototype rotor blade was fabricated, tested and an efficiency of 29% was achieved. Further modification was done and a more efficient rotor blade was fabricated which achieved an efficiency of 45%. A maximum power output of 111.64 W at a wind speed of 8.57 m/s with line voltages of 75 V, 85 V, 81 V and currents of 0.68 A, 0.88 A and 0.85 A respectively for line L1, L2 and L3 were obtained when the blade was connected to a three phase generator. The line voltages and currents obtained were with a torque of 143.8 N-m. A field test was also done at Ngong hills at a height of 2460m (8070 ft) above the sea level and a maximum wind speed of 6.44 m/s was reached at the time of testing. Voltage and current linesof 57.6 V, 57.98 V, 57.60 V and 0.88 A, 0.90 A and 0.80 A were recorded for each line giving a maximum output power of 85.95 W. The Vac from the generator was then rectified by a bridge rectifier and a maximum voltage obtained was 10.5 Vdc which was then used to charge a 12 V dc lead battery. The battery was fully charged after 11 hours and 36 minutes and used to light a 12Vdc bulb for 7 hours. The total cost of developing the rotor blade was Kshs 79,800 which was found to be 58.5 % cheaper than rotor blades in the local market of the similar rating. The above tests led to a conclusion that it is possible to locally develop a wind conversion technology that is affordable, efficient and adaptable for Kenya's average wind speed of 4 m/s.

Perancangan Turbin Angin Tipe Savonius Dua Tingkat Dengan Kapasitas 100 Watt Untuk Gedung Syariah Hotel Solo

Abstract: Urban area has higher energy consumption than the rural or village area. The energy need of a country is mainly determined by energy consumption in the urban and city areas. On the other hand the dependency to the energy from fossil fuel must be reduced. Therefore to fulfill the energy needs in urban area, a clean and renewable energy must be used. One of the eco friendly and renewable energy that can be produced in urban area is wind energy. In this paper a Savonius wind turbine that has 100 Watt capacity was designed to produce energy in urban area. The Savonius wind turbine was designed to be installed on the roof of the Syariah Hotel Solo. The maximum wind velocity on the roof top based on the wind speed data recorded in the Adisumarmo Airport Surakarta, was 6.71 m/s. The Savonius wind turbine design has power coefficient (Cp) of 0.18 and tip speed ratio (λ) of 1. The aspect ratio (α) and the overlap ratio (β) of the wind turbine are 2 and 0.2 respectively. The turbine has 2 semi circular blade and has height (H) of 1.85 m and rotor diameter (D) of 0.92 m. Keywords : U rban area , R enewable energy , W ind turbine , S avonius , 100 W

Study of a Small Incurved Savonius Wind Rotor: Experimental Validation

Abstract: The main objective of this paper is to validate the numerical results developed with the Computational Fluid Dynamics (CFD) code. For thus, a small incurved Savonius wind rotor with a height of 300mm and a bucket diameter of 100 mm is designed and built. This rotor is placed in a wind tunnel test section of 400 mm x 400 mm. The prototype is used to estimate the velocity profiles. For thus, a thermal velocity probe anemometer was used to measure the air velocity. The air speed at the tunnel test section was varied between 0 and 17 m.s -1 . The Conformity between the numerical and the experimental results validate the numerical method developed elsewhere.

A Simulation Study of Flow and Pressure Distribution Patterns in a Two Stage Three Bucket Savonius Vertical Axis Wind Turbine

Abstract: Performance of Savonius vertical axis wind turbine can be increased by incorporating end plates, deflector plates, curtains, shielding, guide vanes etc in their designs. However, multi-staging of conventional VAWT rotors could be a viable proposition in terms of improvement of power output. Numerical analysis involving three bucket Savonius turbines are not available in the open domain. The objective of the present numerical investigation is to study the flow and pressure distribution patterns in the two-stage three bucket Savonius vertical axis wind turbine. The performance of SVAWT is based on the maximum difference in pressure between the upstream and downstream of the turbine. Velocity vector plots shows the energy transfer occurring from the fluid to the blade within the flow field in the upstream and downstream of the turbine. The trail of the wake left behind the SVAWT was observed in the downstream of the turbine. It is observed that eddies in large scale are present around the turbine flow field.

Design and testing of an efficient savonius wind turbine’s rotor blade for low wind speed applications.

Abstract: Studies indicate that vertical axis wind turbines provide a more reliable energy conversion technology, as compared to horizontal axis wind turbines, especially in areas of lowly rated and/or uncertain wind speeds. The challenge however is the development of an efficient Savonius rotor blade which is affordable to low income earners in Kenya. The author researched on different technical design solutions and their advantages in terms of noise, shadows and impacts on birds and wildlife. The objectives of this research were thus to design and develop a Savonius rotor blade locally with locally availlable materials and compare its performance and production cost with the existing blades. The blades were made using glass reinforced fibre because of the light weight of the material which enables it to rotate at very low wind speed, it is also long lasting and does not rot hence can survive in all weather conditions. A prototype was made and after testing and understanding it, a more efficient rotor blade was made. Laboratory and field tests were then done. From the developed blade, a laboratory test was conducted using an industrial fan which could go at a maximum speed of 960 revolutions per minute (RPM) which was calibrated to generate an equivalent wind speed of 15 m/s (meters per second). A torque of 367.57 NM (Newton-metre) at a wind speed of 13.7 m/s was obtained. When the blade was connected to a three phase generator, the line voltages obtained were: 7.5, 8.5, and 8.1 V for line L1, L2 and L3 respectively. The Vac from the generator was then rectified by a bridge rectifier and a maximum voltage obtained was 10.5 Vdc which was then used to charge a 12 V dc lead battery. The battery was fully charged after 11 hours, 36 minutes and used to light a 12Vdc bulb for 7 hours. A field test was also done at Ngong hills at a height above the sea level of 2460m (8070 ft) and a maximum wind speed of 6.44 m/s was reached at the time of testing. The angular velocity obtained was 13.58rads/sec, voltage of 5.63V, 6.2V and 5.93V was recorded for each line. The above laboratory test led to a conclusion that it was possible to locally develop a wind conversion technology that is affordable, efficient and adaptable for Kenya’s average wind speed of 4m/s.

Doe를 이용한 3엽식 사보니우스 풍력발전기의 구조 최적화

Abstract: A Savonius wind turbine is a vertical-type wind turbine system using the drag force, and since its efficiency is lower than that of the existing horizontal-type wind turbines and the range of operation is narrow, it is necessary to determine the condition of the optimized shapes in designing a system. This is because it is necessary to find the condition in which it can yield the maximum drag force to wind pressure, and it is necessary to construct a system that has the minimum mechanical loss. Especially, by the characteristic of the vertical-type wind turbine, which should be able to be driven at a low wind speed, the optimal design specifications of the material weight and shape of the components of the system should be found. This study performed structural optimization of the conditions of the material and shape of a 3-bladed Savonius wind turbine using finite element method and optimal design method, and in order to draw a plan for the optimal design of the 3-bladed Savonius wind turbine, a meta-model was used. Also, by applying the calculated optimization parameters to the finite element method, the structural stability of the wind turbine against loads was judged. It is judged that, through this study, it will be possible to predict the optimal design parameters of wind turbines in various forms and the structural stability under the applied loading conditions, using the optimal design method.