http://granitegeek.disqus.com/enTue, 22 Dec 2009 08:54:39 -0000http://granitegeek.org/blog/2009/12/21/cool-mass-wind-turbine-design-gets-nod-from-energy-secretary/#comment-26952591<p>Perhaps - and I speak as somebody who knows nothing whatsoever about the topic - advances since then in materials (lighter and stronger) and turbines (more efficient) could make this possible.</p><p>If nothing else, a good well-funded design that flops could prevent other people from wandering down a mistaken path. </p>DaveBrooksTue, 22 Dec 2009 08:54:39 -0000http://granitegeek.org/blog/2009/12/21/cool-mass-wind-turbine-design-gets-nod-from-energy-secretary/#comment-26904544<p>Yet another ducted fan windmill. I built one of these when I worked for Zephyr Wind Dynamo in Brunswick, Maine about the year 1975 or so. The owner of the company designed a ten foot diameter wheel surrounded by a 16 foot shroud that was supposed to concentrate the wind on the blades. The perimeter of the wheel had many high-strength magnets that acted on the coils outside of the rim to act as an alternator. <br>We had some problems. First and most important, we soon realized that the weight of the shroud made pointing the machine into the wind difficult. <br>Next, if the blades were simply made to be the same diameter of the shroud, we would get the same energy out without the weight and construction complexity of the shroud.<br>The next problem was that with such a large diameter permanent magnet generator, cogging would keep the generator from turning from a dead stop. The attraction of the magnets to the coil pole pieces would lock the generator in one place. That was fixed by making the generator three phase (to start) and later six phase. That small offset in the coils greatly reduced the cogging with some additional electronics mostly consisting of another bridge rectifier for each phase.<br>We built one machine, put it up and it sort of ran and generated some power. Throughout the industry, there was a need for a low speed generator that could be directly connected to hydro or wind powered systems. So, a reduction to two foot diameter, multi-phase generators became the product line. They were moderately successful, but I've never seen one in actual use.</p><p>Earle Rich On the road headed south.</p>earlerichMon, 21 Dec 2009 19:10:56 -0000