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Uploaded on Apr 15, 2010
Some improptu video of very early design testing of a half-scale impeller model under unfavorable wind conditions. Site has low average wind speeds (less than 5mph; strongest recorded gust 17 mph) and experiences extreme turbulence. Site is actually 12 feet lower than the nearest obstructions (to the north & east). So, this is was a good test for developing usable torque under far from ideal conditions.
Dorje Inc is currently developing other impeller designs for medium to high wind conditions. We feel strongly that the impeller should match the site conditions for our installations.
Why vertical axis wind turbines (VAWT)? We have many reasons for this choice; some are engineering and performance based, others are ecologically based.
VAWT designs are very tolerant of turbulence, and therefore are suited for rooftop installations or other less ideal conditions. They are easier to brake and apply maglev technology to (floating magnetic bearings for axial loads). Also, the design is inherently omnidirectional. Even abrupt changes in wind direction don't matter at all.
But primarly -- from an engineering standpoint -- VAWT turbines are high-torque, low-RPM systems. Horizontal wind turbines (propeller or fan-blade types) are low-torque and high-RPM systems. With the proper gearing, we can get a lot more power production out of a VAWT system without needing ideal conditions. Horizontals are very finicky about their wind, and an ideal installation places them 30 feet ABOVE the nearest obstruction. That's quite a tower.
Ecologically, VAWT designs also make better sense. Birds and bats sense these machines as solid objects and can easily avoid them. At no time does a working VAWT become a high-speed blur!
Bird strikes are already a serious concern with horizontal designs and new research is showing how dangerous horizontal utility-grade installations are to bat populations, which suffer lethal pulmonary edema from coming close to the pressure wave the blades produce. There is no data on residential horizontal wind turbines as yet, so we can only speculate as to what a neighborhood filled with whirling thin blades could do to the local bird & bat population.