Carbon Concepts Develop Silent Vertical Axis Turbine
Carbon Concepts, UK based designers of lightweight composite structures, have developed a near silent vertical axis turbine for domestic and industrial use.
The company have developed carbon fibre technology for a variety of industries and applications, and applied their experiences with aerodynamics and composite construction to create an innovative vertical axis turbine which claims to offer an almost silent operation, even at high speed and load. The company hope that this near-silent operation, along with the additional advantage of the design being more inconspicuous, will attract substantial interest from residential users.
The company also believe that the technology will yield great benefits to industry, and are actively promoting the generator and composite blade technology to manufacturers and distributors of small wind and water turbines.
The design of the first installation was completed in conjunction with the University of Nottingham. The work was carried out as a fourth year Group Development Project by four students completing their M. Eng. degree. The design brief was that the installation should be fully portable. It can be erected by two people without the need for special tooling or lifting equipment and is transported on a small boat trailer.
The vertical axis machines are generically quieter than traditional wind turbines, with the novel design of the blade tips rendering the turbine virtually silent even at the highest speeds. The company do credit outside assistance, with much of the aerodynamic technology being built on the electrical generator and aerodynamic expertise from the University of Durham.
The disadvantages of a vertical axis system is that the engineering is more complicated and very intolerant of poor aerodynamics, with the blade stresses being much higher. However, Carbon Concepts suggest that the advantages are critical to the acceptability of small wind turbines, particularly when mounted on or close to buildings. This is of particular importance for urban installations where local authorities are seeking to meet current energy targets.
The performance and cost effectiveness of the wind turbine derive from the advanced technology generator and the aerodynamics and structure of the rotor set. The rotor has been designed in accordance with the best available low speed aerodynamic technology and is fully optimised for the unusual conditions of the vertical axis wind turbine.
The turbine currently drives an electrical generator, but would equally support water or hydraulic pumps and heat pumps.
Most of the functionality of the turbine is based around the use of carbon fibre, a material which has added fatigue resistance, with many other vertical turbines having failed through fatigue in similar aluminium structures, according to the company.
Testing has confirmed that, even at high speed and load, the rotor is effectively silent, and attempts to measure the noise of the rotor showed that perceived noise was dominated by the wind and adjacent trees.
The turbine also has a carbon spar made with glass fibre skins, which is required to keep the fatigue levels below the endurance limit, providing a virtually infinite life.
Whilst the new designs are still in the development stage, the first wind turbine has now completed its initial performance evaluation and is currently undergoing endurance and structural testing while the final control system is optimised. The first turbines have been built as fully portable, stand alone units and the company are now very close to a production machine and are looking to speak to possible collaborators.
Publication date: 07/10/2005