CFD analysis of a hybrid, Darrieus-Savonius, horizontal wind turbine, using static and moving mesh

Abstract

Abstract Changes in the ecological spirit of the world lead to the need for usage of additional ways of obtaining clean energy. With help comes solutions to use wind energy. In the world, there are numerous commonly used, various kinds of wind turbines of different sizes, numbers of generated power and the different place of use. They are increasingly used as household wind turbines to improve the ecology and a marked decrease in household spending. Moreover, it was decided to use an innovative, previously unused connection of two separate types of wind turbines. The approach to turbine positioning is also innovative. Due to the use of its horizontal orientation and purpose to mounting on the roofs of the buildings, to do not exceed the specified size limits in building regulations. It also allows increasing the number of applications of this solution. With the use of Darrieus - Savonius turbine increasing of the range of the wind speeds, which are able to spin a turbine is achieved. In the case of higher efficiency, the Darrieus turbine operates at high wind speeds, while the Savonius turbine at lower wind speeds. Two separate solutions have been coupled with each other by claw clutch, which allows the rotation of only one part or two parts of the turbine depending on the prevailing wind conditions. The CAD model of the turbine was made and then the turbine was subjected to advanced CFD analysis. Initially, analysis of the air course around the turbine was performed, using statistical and analytical data on wind speeds prevailing in Poland, within the areas of single-family houses. The approximate values of the wind flow streams and the torque which ultimately is moving the electric generator were determined. The subsequent CFD analysis was performed using the moving FEM mesh, mapping the actual velocities of the turbine blades. The turbine blades revolved at velocities close to the obtained analytical speed of the shaft and turbine components. Airspeeds were analysed in the case of the shape of the flow of streams. The pressure of the air around the turbine was also analysed, the value of which could be used to add strength analysis using FEM method. The main purpose of the test was to determine the torque acting on the engine. Thanks to this information, it was possible to determine the energy efficiency of the turbine and select the appropriate elements, such as the generator, bearings etc. The obtained information has also had an impact on the final shape of the turbine’s executive elements. Thanks to performed analysis, it was possible to obtain proper turbine performance parameters without conducting expensive, real, experiments. In the end, the prototype of this Darrieus – Savonius turbine was manufactured.