62 research outputs found
Performance enhancement of a twisted Savonius hydrokinetic turbine with an upstream deflector
No full textThe conventional Savonius turbine is one of the most used rotors to convert the kinetic energy of natural water resources instead of potential energy. However, this rotor presents low efficiency. A twisted Savonius turbine was appeared which is considered most performant by twisting the blades of the conventional Savonius turbine along theirs spans. In fact, various experimental and numerical investigations were carried out to enhance the efficiency of the twisted Savonius turbine which has not been completely explored. In this study, an experimental investigation was carried out to assess the performance characteristics of a twisted Savonius turbine in an irrigation canal. In order to improve the efficiency of the Savonius turbine, three deflector designs were investigated numerically based on a CFD 3D numerical model. The peak value of the turbine power coefficient reaches 0.166 at a tip-speed ratio value of 0.78 without using a deflector upstream the turbine. Using the deflector design showing the highest efficiency, the peak value of the power coefficient was increased by 17.47%. The use of the proposed deflector is expected to provide toward a more effective employment of flowing water like tidal currents, river streams or other man-made water channels for electrical energy production in rural regions
Experimental and numerical investigation of the leading edge sweep angle effect on the performance of a delta blades hydrokinetic turbine
No full textIn the last decades, an increase of energy consumption has been noted around the world. Hence, the excessive use of fossil fuels can lead to serious environmental concerns. Indeed, the use of renewable energy sources is needed to reduce the greenhouse gas effects and the CO2 emissions in the atmosphere. Small-scale hydropower could be an interesting and renewable alternative solution. The cross-flow turbines present several advantages compared to the axial-flow turbines. Therefore, increasing efforts are taken to enhance the efficiency and extend the applicability of the cross-flow turbines. In this paper, experimental investigation was carried out to evaluate the performance of a delta blades turbine with leading edge sweep angle equal to γ=30°. The experimental investigation was conducted in an irrigation channel characterized by a water current of constant velocity equal to =0.86 m.s-1. In addition, numerical study was carried out to analyze the effect of the leading edge sweep angle on the performance of the delta blades turbine and the hydrodynamic characteristics of the flow around the turbine. Numerical findings confirm that the leading edge sweep angle has an impact on turbine efficiency and the hydrodynamic characteristics of the flow around the turbine
Performance study of a Helical Savonius hydrokinetic turbine with a new deflector system design
No full textThe use of renewable energy sources has becoming a necessity to generate electricity. Helical Savonius rotors have been preferred for small-scale hydropower generation. Numerous studies were carried out to improve the performance of the Helical Savonius rotor which has not been fully explored. In this paper, an experimental study was carried out to evaluate the performance of a Helical Savonius water rotor in an irrigation channel. In order to enhance the performance of the studied water rotor, a new deflector system design was proposed. Different configurations of the proposed deflector system were tested numerically using the commercial software ANSYS FLUENT 17.0. Without a deflector system, the maximum power coefficient is found to be equal to 0.125 at tip-speed ratio of 0.7. Using the optimal configuration of the new deflector system, the maximum power coefficient reaches 0.14. The utilization of this new design system is predicted to contribute towards a more efficient use of flows in rivers and channels for electricity production in rural areas
Performance Improvement in a Helical Savonius Wind Rotor
No full textAbove 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 SSTk-omega 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
Performance improvement of a Savonius water rotor with novel blade shapes
No full textSavonius water rotor is a prominent drag based turbine able to extract energy available in flowing water with low
velocity like river streams, tidal currents or other man made water canals. However, in view of its low perfor-
mance, an enhanced design of the rotor blades is necessary to better its efficiency. Therefore, the present study
aims to improve the efficiency of Savonius rotor by changing the blade design. Different blade shapes were
investigated numerically using computational fluid dynamics (CFD). Using conventional design, the peak power
coefficient was found to be 0.166 at tip-speed ratio of 0.78. However, the peak power coefficient reaches 0.184
using the optimal blade design. This work may be an important towards further improvement of the Savonius
rotor’s efficienc
Numerical and experimental investigation for helical savonius rotor performance improvement using novel blade shapes
No full textWind energy is extensively invested as a renewable and clean energy source. Savonius wind rotor, as an energy converter, has the merit of being appropriate for specific applications. The current paper centers on the performance enhancement of a helical Savonius wind rotor through the blade shape modification. The basic objective is to assess and compare, numerically and experimentally, the performance of two rotors with novel blade shapes named delta bladed and two-stage delta bladed shapes in relation to a helical Savonius rotor. Numerical study was conducted using Ansys Fluent software. 3-D unsteady simulations were carried out through the use of the SST k-ω turbulence model based on the finite volume method solver. Aerodynamic flow and performance characteristics were investigated. Static and dynamic experimental tests were undertaken on a wind tunnel. An improvement in Cp by 22.58 % and 29.5 % for the two-stage delta bladed rotor and 19.35 % and 16.4 % for the delta bladed rotor over the helical Savonius rotor was recorded, respectively, numerically and experimentally. In addition, the self-starting ability as well as the aerodynamic flow characteristics of the helical rotor were enhanced with the novel blade shapes
Numerical Model Parameters Choice of Helical Savonius Wind Rotor: CFD Investigation and Experimental Validation
No full textElectrical power is essential for human beings welfare. The available wind as a clean and renewable source of energy has whetted extensive interest over decades. Savonius vertical axis wind rotor as an energy converter has the merit of being adequate for specific implementations owing to its lower cost and independency on wind direction. From this perspective, multiple studies have been conducted to boost its efficiency. This research work emphasizes on the helical Savonius wind rotor (HSWR). The basic objective is to investigate the impact of selecting the numerical model parameters on its aerodynamic and performance characteristics. Experimental tests were realized with a 3D printed HSWR in a wind tunnel. The experimental performances in terms of power, static and dynamic torque coefficients were addressed. Next, a numerical study was undertaken through Ansys Fluent 17.0 software. Grid, turbulence model and rotating domain size tests were examined. Good accordance was obtained, which validated the numerical model with an averaged error of 5%. The maximum power coefficient proved to be equal to 0.124 at a tip speed ratio of 0.73 and 0.1224 at a tip speed ratio of 0.69, respectively, numerically and experimentall
Performance Investigation of a Twisted Savonius Wind Rotor
No full textFor human welfare, electrical power is necessary. For many years, there has been a great deal of interest in wind energy because it is a clean, sustainable energy source. Because of its cheaper cost and independence from wind direction, the Savonius vertical axis wind rotor has the advantage of being suitable for certain implementations as an energy converter. Several studies have been carried out to increase its efficiency. In this paper, a novel blade design of a twisted Savonius wind rotor has been investigated numerically with the intention of performance betterment. Three-dimensional unsteady simulations were performed deploying Ansys Fluent using the Shear Stress Transport k-ω turbulence model based on the finite volume method solver. The wind flow aerodynamic characteristics in addition to the rotor performance properties were acquired and analyzed. The numerical model was validated based on findings taken from experimental tests performed on a 3-D printed twisted rotor in a wind tunnel. An improvement in the power coefficient by 22.58 % was recorded with the novel blade design over the twisted Savonius wind rotor. The obtained findings could provide further direction for researchers to use the twisted Savonius wind turbine in power generation
Effect of the Converging Pipe on the Performance of a Lucid Spherical Rotor
No full textLucid spherical rotor is a cross-flow rotor developed to be installed within a pipeline. The purpose of installing this type of rotor is to collect excess energy available in gravity-fed water pipelines. In order to enhance the efficiency of the rotor which is installed in a channel, this paper aims to study the performance of Lucid spherical rotor with converging pipe. Numerical investigations were carried out to analyze the effect of the converging pipe on the performance of the rotor. Numerical simulations have been carried out using the unsteady Reynolds-averaged Navier–Stokes equations in conjunction with the realizable k −ε turbulence model. The validation of the numerical method with anterior published studies has been carried out. The hydrodynamic characteristics of the flow around therotor with and without converging pipe have been analyzed and discussed. Numerical results indicated that the converging pipe increases the performance of the Lucid spherical rotor
Investigation of a helical Savonius turbine with a deflector system
No full textThe growing demand for renewable energy sources to meet electricity needs has underscored the importance of exploring new resources of renewable energy. Among the various alternatives, Helical Savonius rotors have emerged as one of the most widely used technologies for small-scale hydropower generation. Numerous studies have been conducted to investigate these types of rotors, particularly to enhance their power output. Despite existing research, there is still a need for modifications and proposals for new configurations of Savonius rotors. This paper presents a numerical study of a Savonius rotor equipped with a new design of a deflector. The results indicate that the highest power coefficient achieved is 0.1247 at a tip-speed ratio of 0.7 in the absence of a deflector system. The geometric parameters of the deflector are varied to identify the configuration that generates the highest power output. With the implementation of an optimal configuration for the new deflector system, the maximum power coefficient is improved to 0.168 at a tip-speed ratio of 0.7. Otherwise, the maximum power coefficient could be enhanced by 34% compared to the same configuration without a deflector. This significant improvement highlights the potential of the proposed design system
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