This paper presents a review on the performance of Savonius wind turbines. This type of turbine is unusual and its application for obtaining useful energy from air stream is an alternative to the use of conventional wind turbines. Simple construction, high start up and full operation moment, wind acceptance from any direction, low noise and angular velocity in operation, reducing wear on moving parts, are some advantages of using this type of machine. Over the years, numerous adaptations for this device were proposed. The variety of possible configurations of the rotor is another advantage in using such machine. Each different arrangement of Savonius rotor affects its performance. Savonius rotor performance is affected by operational conditions, geometric and air flow parameters. The range of reported values for maximum averaged power coefficient includes values around 0.05–0.30 for most settings. Performance gains of up to 50% for tip speed ratio of maximum averaged power coefficient are also reported with the use of stators. Present article aims to gather relevant information about Savonius turbines, bringing a discussion about their performance. It is intended to provide useful knowledge for future studies.

A review on the performance of Savonius wind turbines

Optimum design configuration of Savonius rotor through wind tunnel experiments

Optimal blade shape of a modified Savonius turbine using an obstacle shielding the returning blade

A double-step Savonius rotor for local production of electricity: a design study

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.

An experimental study on improvement of savonius rotor performance

A comparative calculation of the wind turbines capacities on the basis of the L–σ criterion

The present paper deals with a comparative Life Cycle Assessment study of two wall assemblies using natural insulating material: linen panels and straw. The Bilan Produit ® software, associated to the eco-invent database is used to quantify the environmental impacts of the analyzed walls. Obviously, some steps of the wall lifecycle have a small environmental footprint: the consumer use step provides little impacts, while the end of life step (post-consumer) allows a saving (diminution?) of impacts because of the "reusing" of (possibility to reuse) a part of the natural materials. On the other side, the raw material procurement and manufacturing steps are at the origin of the greatest impacts. The linen panel is a rather complex manufactured product, so that the order of height of the impacts is greatly superior to the one of the straw wall. To minimize the impacts (environmental footprint) of this step, local producers should be preferred. Both assemblies are finally compared to a conventional wall realized by using glass wool. According to the obtained results Straw is shown to be better for the environment than the linseed whatever the considered indicator. Besides, the wall with linen panels is finally more impacting for the environment than a conventional wall, so that the only alternative to the conventional insulation for the environmental point of view seems to be the straw.

https://hal.archives-ouvertes.fr/hal-00952027/document

A comparative life cycle assessment of exterior walls constructed using natural insulation materials

The knowledge of wind field characteristics around buildings is very useful in a variety of applications such as energy supply by means of a domestic wind turbine. In this paper, results of a wind study around a conventional pitched roof building are given in order to choose the best location and therefore to maximize a micro-wind turbine production. Numerical results on a bluff body (cube) have been performed by means of computational fluid dynamics techniques and the Reynolds Averaged Navier-Stokes approach has been used to model the flow. Several turbulence models coupled to different near-wall treatments have been tested and have thus allowed one to determine the optimal configuration. Numerical model validation through the experimental data available in literature has made it possible to extend the study to a cube equipped with a pitched roof. Both sets of results thus obtained have allowed one to discriminate the effects from this particular element. Some of the computed data will be given in this paper in order to highlight the most significant regions relative to wind potential for a range of wind incidence angles. Some over speed areas have been found in the vicinity of the pitched cube for low altitudes. Finally, a simple method to map wind potential around buildings is proposed and a case study is presented. It deals with wind potential estimation for an isolated pitched roof building in Valenciennes (North of France). It is shown that some areas are beneficial for a micro wind turbine installation, even close to the building.

Wind potential evaluation around isolated pitched roof buildings

The Savonius rotor is a slow running vertical axis wind turbine, the advantages of which are numerous ; however, it has a poor aerodynamic efficiency and a very unsteady mechanical torque. We present the results of numerical simulations of the flow around derived Savonius rotors, aiming to raise and stabilise the torque. It is the reason why several geometrical parameters have been adjusted, in particular the overlap of the paddles and their respective position. Then a rotor with displaced blades is studied. The results obtained on few configurations of rotors show that the two-bladed rotor, called reverse paddles rotor, seems to be the most efficient. Mots-clefs : rotor Savonius ; rotor a contrevoiles ; CFD, optimisation

http://documents.irevues.inist.fr/bitstream/handle/2042/15895/CFM2007-0021.pdf;sequence=1

Jean-Luc Menet

Papers

A double-step Savonius rotor for local production of electricity: a design study

A comparative calculation of the wind turbines capacities on the basis of the L–σ criterion

A comparative life cycle assessment of exterior walls constructed using natural insulation materials

Wind potential evaluation around isolated pitched roof buildings

Prévision des performances aérodynamiques d'un nouveau type d'éolienne à axe vertical : le rotor à contrevoiles