M. H. Nasef
Bio: M. H. Nasef is an academic researcher from Sinai University. The author has contributed to research in topic(s): Rotor (electric) & Wind tunnel. The author has an hindex of 1, co-authored 2 publication(s) receiving 172 citation(s).
TL;DR: In this paper, different geometries of Savonius wind turbine are experimentally studied in order to determine the most effective operation parameters, it was found that, the two blades rotor is more efficient than three and four ones.
Abstract: For solving the world energy problem and the bad effect of conventional sources of energy on environment, great attention allover the world is paid towards the use of renewable energy sources. Special interest is paid towards wind energy because of its competitively. Savonius rotor is a vertical axis wind turbine which is characterized as cheaper, simpler in construction and low speed turbine. This makes it suitable for generating mechanical energy in many countries especially in Egypt. In this work different geometries of Savonius wind turbine are experimentally studied in order to determine the most effective operation parameters. It was found that, the two blades rotor is more efficient than three and four ones. The rotor with end plates gives higher efficiency than those of without end plates. Double stage rotors have higher performance compared to single stage rotors. The rotors without overlap ratio (β) are better in operation than those with overlap. The results show also that the power coefficient increases with rising the aspect ratio (α). The conclusions from the measurements of the static torque for each rotor at different wind speeds verify the above summarized results of this work.
01 Jan 2011
TL;DR: In this article, the Savonius rotor prototype was designed and tested in El-Arish at the Faculty of Engineering, Sinai University, and the results showed that the rotor gave considerable efficiency and began to give power at a relative low wind speed.
Abstract: In this work, it is planned to design and test a prototype of Savonius rotor in free wind based on the results of the previous experimental study. The prototype is designed and tested in El-Arish at the Faculty of Engineering, Sinai University. Although El-Arish has lower average yearly wind speed compared to other locations with higher average wind speed, like Hurghada. The results show that Savonius rotor prototype in El-Arish gives considerable efficiency and begins to give power at a relative low wind speed. While the energy generated from the Savonius rotor prototype in El-Arish is small, the cost of energy generated is competitive with other energy sources. The cost of kW hr generated from Savonius rotor is expected to be very low specially in locations with high average wind speed. The majority of the Egyptian locations having an average wind speed between 3.5 and 4.5 m/s. The cost of kW.hr generated from Savonius rotor in these locations is expected to be between 0.42 and 0.28 LE. In locations where average wind speed is 6 m/s, the cost of kW hr is expected to be 0.1 LE. Therefore the use of Savonius rotor will be attractive in many locations in Egypt and it can be used to pump water for irrigation of lands. This will save a great part of conventional energy sources used for this purpose and consequently reduces the environmental pollution. بط ُّيبرٕج تب زنط عنُ منًلج بناضأ يُنصحنا ةهٓطٔ ًٍثنا ةصيخر بَٓأب شيًحج ٗحنا ةيطأزنا تبُيبرٕحنا ٍي ْٗ ّيئإٓنا صٕيَٕف ّافخُي ءإْ , زصي بُٓئ ّييبُنا لٔعنا ٗف بٓياعخحطا ٍكًض ٗحنا ّيئإٓنا تبُيبرٕحنا مافا ٍي بٓهلجض كنذ . زحن ٗننٔأ وذٕنًَ ربناحخخٔ يُنصجٔ ىيًصج ىج مًلنا اذْ ٗف تبنطبي نا تئبنحَ ٗنه اعنًحلي زنتنا ءإنٓنا ٗنف ةنيئإٓنا صٕيَٕفبنط ةنُيب ةنيهكب مةنيكيَبكيًنا ٖٕن نا ةنطعُْ ىنظ ب موعن حًنا نئإًنا بنكيَبكيي منًلي ٗنف صٕيَٕفبط ةُيبزج ٍي وذبًَ ٗه ثضزجأ ٗحنا ةيهًلًنا ةيفًُٕنا ةليبج مةطعُٓنا . شضزلنا ةُضعي ٗف ٗنٔلأا وذًُٕنا رباحخخٔ يُصج ىج ءبُيط ةليبج مةطعُٓنا ةيهكب . شضزنلنا ٌأ ٍني ىأزنبنب اذنْ مةنافخُي نبنضر تب زنط عنُ ةقبط عينٕج ٗف أعاضٔ مةنٕ لي ةءبفكب مًلض ٗنٔلأا وذًُٕنا ٌا عجٔ ع نٔ ةافخًُنا نبضزنا تب زط تاذ ةضزصًنا قطبًُنا ٍي زاحلج . ٕحًنا ةنقبطنا ٍني منقا زاحلج صٕيَٕفبط ةُيبزج ٍي ةعنٕحًنا ةقبطنا ةءبنف ٌلأ كننذٔ ةنينبلنا تب زنظنا تاذ ةني فلأا تبنُيبزحنا ٍني ةعنن ةنقبطهن ٖزنخلأا رلبنصًنا ضفبنُجٔ ةنافخُي زناحلج صٕيَٕفبنط ةنُيبزج ٍني ةنجحًُنا ةنقبطنا ةعحٔ ةفهكج ٍكنٔ ممقأ صٕيَٕفبط ةُيبزج ةُيبزحنا ِذْ ءبشَلإ ةافخًُنا ةفهكحنا باظب كنذٔ . نُي ىظلي ٗف ةططٕحًنا نبضزنا ة زط ٌخ ٍينب ن ج زنصي قطب 3.54.5 m/s ٔ م دق ل ةنفهكج ٌأ عنجٔ kW hr ةنُيبزج ٍني تحنًُنا ٍيب حط زصي قطبُي ىظلي ٗف صٕيَٕفبط 0.42-0.28 LE ٗننخ منصحن ةنفهكحنا من ج إنط بنًُيب ماعنج ةننٕ لي ةنفهكج ٗنْٔ LE 0.1 ةططٕحًنا نبضزنا ة زط بٓب ٗحنا قطبًُنا ٗف m/s 6 . يبزج واعخحطخ ٌإف كنذنٔ ةزنيث قطبنُي ٗنف ةنقبطنا عينٕحن صٕيَٕفبط ةُ ةزنيا ةنيًْأ ّنن ٌٕكينط زنصي ٗنف . ٗن ارلأا ٖزنن ةنيس ا ِبنيًنا رنان تبناًهطنا ةرالخ ٗنف ةنُيبزحنا ِذنْ واعخحنطخ ٍنكًًنا ٍنئ ا ٍني بناضأ منه ض إنطٔ متباًهطنا ِذْ ةرالخ ٗف وعخحظًنا ٖعيه حنا لٕقٕنا ٍي ةنٕ لي تبيً زفٕض إط اذْ مةي ارشنا تبنثبلاَلإ ٗئيانا خٕهحهن ةااظًنا ةضرازتنا .
TL;DR: In this paper, an attempt has been made to review hydrokinetic energy theory for energy conversion system from water currents analogous to wind power system, and the most widespread classes of hydro-kinetic turbines are discussed in detail with respect to their benefits, drawbacks and desirable conditions for applications.
Abstract: Energy crisis and high emission of fossil fuels are major driving forces for developing renewable energy based technologies. In order to meet growing demand for energy, hydropower can be one of the sustainable alternatives. Further, the hydrokinetic turbine is considered as one of the most emerging technologies which harness energy from flowing water. In this paper, an attempt has been made to review hydrokinetic energy theory for energy conversion system from water currents analogous to wind power system. The most widespread classes of hydrokinetic turbines are discussed in detail with respect to their benefits, drawbacks and desirable conditions for applications. It has been found that in spite of some prevailing downsides of vertical axis turbine like of self-starting and lower efficiency, vertical axis turbines are appealing for many riverine applications. One of the prominent turbines of its kind is the Savonius hydrokinetic turbine that has the capacity to self-start at a very low fluid velocity in the river, canal etc. However, Savonius type hydrokinetic turbine inherently has poor efficiency. A number of experimental and numerical studies with a large number of physical designs and parameters have been carried out in the area of Savonius rotor to enhance its efficiency. Under this study, review of different parameters affecting the performance of Savonius hydrokinetic turbine has been carried out and presented in this paper which may be useful for future studies to improve the efficiency of such turbines.
TL;DR: In this paper, three methods of controlling the wind direction were proposed aiming at improving the performance of Savonius rotor, which achieved a power-coefficient peak of 0.52 with operation range of tip speed ratio λ ≤ 2.2.
Abstract: In this work three methods of controlling the wind direction were aiming at improving the performance of Savonius rotor. The idea behind the new designs was to harvest the incoming wind to generate a wind jet to the concave side of the advanced blade and prevent the convex side of return blade from coming upwind stream. The prevented wind was guided in different designs to impinge the concave side of the return blade and hence to eliminate the negative torque and increase the exerted positive torque. The study could be numerically introduced using commercial Fluent-software. The SST k-ω turbulence model was used to simulate the turbulence behavior. The results showed that the suggested designs improve the performance of Savonius rotor in view of the power coefficient and the operation range. One of them enhanced the performance to reach a power-coefficient peak of 0.52 with operation range of tip speed ratio λ ≤ 2.2 . However, the new designs generated large wakes behind the rotor that must be considered in the turbines farm arrangement.
TL;DR: In this article, the performance of the Savonius hydrokinetic turbine (SHT) has been evaluated through simulation and experimental and computational fluid dynamics (CFD) analysis.
Abstract: The drag-based Savonius hydrokinetic turbine (SHT) has an enormous potential for small-scale power generation from free-flowing water and it can be deployed especially at sites remote from existing electricity grids. These turbines can be installed in waves, tides, ocean currents, natural flow of water in rivers, manmade channels and irrigation canals to produce power. The performance of a SHT are highly influenced by its design parameters such as blade profile, number of blades, overlap ratio and aspect ratio. Although, over a period of nine dacade since its invention, serveral studies have been carried out, however, no particular concencus on the optimum design of SHT is arrived. In view of this, in the present investigation, as attempt has been made to parametrically evaluate the performance of the SHT through experimental and computational fluid dynamics (CFD) analysis. The SHT under investigation has been developed in-house. Initially, a comparison of performance between two- and three-bladed SHT with conventional semicircular blades has been carried out experimentally where their maximum power coefficients are found to be 0.28 and 0.17, respectively at their corresponding tip-speed ratios of 0.84 and 0.67. Further experiments with a two-bladed SHT turbine with elliptical blades have shown its inferior performance as compared to the two-bladed semicircular SHT. The reason behind the enhanced performance of the two-bladed semicircular SHT is then analyzed through two-dimensional CFD simulations. Finally, the experiments are conducted at various immersion levels, where the performances of the SHTs are found to degrade with a decrease in immersion. However, the two-bladed semicircular SHT maintains to have a better performance than the others.
01 May 2017-Renewable Energy
TL;DR: In this paper, a CFD study is conducted in order to characterize the dynamic behavior of a Savonius vertical axis wind turbine, which is executed using the open source code, OpenFOAM.
Abstract: A CFD study is conducted in order to characterize the dynamic behavior of a Savonius vertical axis wind turbine. All simulations are executed using the open source code, OpenFOAM. Both two-dimensional and full three-dimensional cases have been investigated in order to provide a suitable tool for geometrical optimization of this rotor. Unsteady simulations are carried out at different tip speed ratio (TSR), varying angular speed of rotor at constant wind speed, using different one and two-equation URANS turbulence models and selecting the k−ω SST for the final analysis. The two-dimensional model was compared with experimental data available in literature and obtained from tests in wind tunnel. This simplified model shows an over-estimation of experimental data, reporting a maximum efficiency at TSR 1, 20% higher than experimental value. The results of 3D model are in good agreement with experiments with a peak of 0.202 at TSR 0.8 for a rotor with aspect ratio 1.1. The influence of the rotor height has been evaluated on flow dynamics of the turbine and its power coefficient.
TL;DR: In this paper, the authors proposed a novel system of ducted nozzle configuration around the Savonius rotor to increase the efficiency of the turbine, and the maximum power coefficient of the ducted turbine was increased by 78% compared to the conventional modified rotor.
Abstract: Savonius turbine presents an attractive, environmentally friendly and cost effective electric generation in low velocity regions. However, this turbine has not been fully explored, as researchers are still searching for solution for the main problem of low efficiency of Savonius turbine configuration. This research paper proposes a novel system of ducted nozzle configuration around Savonius rotor to increase the efficiency of the turbine. In this study, six different duct nozzle designs had been investigated. A numerical investigation was carried out in this research work using finite volume Reynolds-Averaged Navier-Stokes Equations (RANSE) code ANSYS Fluent with Reynolds numbers of 1.32 × 10 5 . Consequently, validation was carried out following previous experiments. Flow characteristics through augmented configuration, and performance of the Savonius turbine had been studied, and it was found that the water flow speed had been enhanced by the developed ducted nozzle system. The maximum power coefficient of the ducted nozzle turbine was increased by 78% compared to the conventional modified rotor. The maximum power coefficient was 0.25 at tip speed ratio (TSR) of 0.73. The use of this system is expected to contribute towards a more efficient utilization of flows in rivers and channels for electrical generation in rural areas.