Referent: Eng. Davide Mavillonio, Eng. Luigi Barile, Eng. Riccardo Castagnoli
Category: Sizing, CAD design, FEM structural analysis and CFD fluid dynamics verification
Ecolibrì, a branch of the company A.C.E. srl based in Agrate Brianza active in the wind market since 2015, has launched the design challenge to expand the already existing range of vertical axis wind turbines with on-grid operation with a higher performance wind turbine blade, equal to 20 kW. The goal of the 20 kW ECOLIBRI’ wind turbine is to support all facilities already connected to an electrical grid with renewable energy.
Four are the main requests that Ecolibrì has put to Asotech technical staff coordinated by Eng. Davide Mavillonio:
Unlike what was done for the 3 kW and 10 kW turbines developed by Ecolibrì in aluminum, for this machine Asotech designed the blades in composite material with main profile in fiberglass and internal reinforcement in carbon fiber. This choice made it possible to reduce the mass of the outermost part of the turbine, thus limiting the forces acting on the system, and to increase the structural resistance, since these materials have higher breaking tensions.
The developed wind turbine has revolutionized the management of the electronic and energy part. In case of low wind, the motor-generator allows to bring the turbine to speeds higher than 50 rpm and to obtain a self-sustainment already with 2 m/s of wind. However, the maximum performance is obtained at 12 m/s, a speed beyond which a brake allows to modulate the speed and to limit it to 100 rpm.
To optimize the basic profiles, Asotech used the Ansys-Fluent simulation software, which made it possible to start the preliminary 2D and 3D analysis of the overall fluid dynamic aspects. In this way, the efficiency curves of the turbine were obtained as the wind speed varied.
Subsequently, the Asotech technical staff solved the problems of CAD design and structural verification, given the use of composite materials.
The development of the turbine has also involved the sizing and verification of the support pole, which was made by optimizing the geometries, so as to offer the highest possible resonance frequency.
The machine has no impact on the environment from an acoustic point of view and, thanks to the composite material with which its blades are made, it resists strong winds of over 60 m/s.
The customer has been able to count on a team of engineers, coordinated by a single contact person, for all phases of work (design, CFD fluid dynamics analysis and FEM structural analysis), thus avoiding the need to deal with several companies or several interlocutors.
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