A Russian entry in the James Dyson Award competition offers a vertical-axis wind turbine design that, from what can be gathered through Google’s translator, capitalizes on aerodynamic design principles, including the angle of attack, to create a wind turbine design that’s said to be smaller and lighter and able to maximum the energy of wind currents.
The ability of vertical-axis wind turbines to capture the wind from all directions is often offered as a selling point by manufacturers of the devices. The Russian designers seem to be claiming an efficiency between 84 and 89 percent, which if true runs headlong into Betz’s assertion of a 59 percent limit.
Wind turbine efficiency is affected by a number of factors, including altitude (the higher the faster the wind blows), obstructions (trees, buildings and the like), the length, width and shape of the blade and the way it is canted, and the air temperature (cold air is also denser than warm air, and exerts more force on turbine blades). The Russian designers point to the independence of individual blades, which can turn around their axis to 360 degrees, allowing each separate blade to achieve its own most efficient angle of attack. And when high winds hit, these vertically mounted blades are said to “feather” instantly and automatically to prevent damage, turning parallel to the airflow.
The Russians say the wind turbine, described as an ecologically safe, mobile power source, also accomplishes two triumphs which have so far eluded horizontal wind turbine manufacturers: a very low level of audible noise, and a total absence of infrasonic noise; that is, sound below 20 hertz that is undetectable to the human (or mammalian) ear. Finally, they say its cut-in — the wind speed at which it begins to produce usable power — is low. Like most of the vertical axis wind turbines we have written about recently – the Savannius and the Revolver – it is designed to fill a specific power niche, serving smaller populations at a distance from the grid.