engleski

Wind Frames in Croatia? Yes, but what kind?

Some attempts to establish the wind turbines in extreme conditions in the coastal area close to Velebit finished in debacle. Probably that is the reason why the authors of the study "Designs of wind frames in Croatia" avoided this area and chose the nearest location on the island Pag. The wind in this area called "bura" (borra) ia a gale-force wind the with highest energy concentration, and lasts for a great number of hours with gusts of over 100 km/h, i. e. velocities when all conventional turbines are unable to function. It is curious that our Faust Vrančić (1615) in "Machine novae" proposed six types of wind turbines with vertical axis and none with a horizontal one. Obviously, he knew the "bura" and its capacity for sudden change of velocity and wind direction well. The theory states that turbines based on drag have a low efficiency in relation to turbines based on lift effects, but they have low cost, very simple design due to lack of a movable part on the rotor, and no transmissions. In the paper we analyze the properties of turbines with vertical axes. One, H-type (only 40 kW) operates in extreme meteorological conditions in Africa. Such turbines are not sensitive to changes of wind direction, and have a high "survive velocities". Some theoretical research has demonstrated that it makes sense to continue to study these kinds of turbines for extreme meteorological conditions.

VAWT; vetical axis wind turbines

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