16-11-2012, 03:45 PM
BUILDING A VERTICAL AXIS DRAG PROPULSION INVOLUTE SPIRAL WIND TURBINE
BUILDING A VERTICAL AXIS.pdf (Size: 4.12 MB / Downloads: 117)
Congratulations! Your purchase of these plans will launch you into a major alternative energy project, with a new wind turbine design that has many exciting advantages over other approaches. These plans are for a 4ft diameter prototype, which is undersized for most energy needs. Dimensions are also given to increase the size for greater power output.
BACKGROUND:
The drawing on the left was first built with sailcloth vanes (see picture below), which proved to be too flexible for optimum performance.
The aluminum-vaned model pictured right was then built. It is a great improvement! I call her “Wendy”
Wind power has the potential to supply much of the energy demands of the world, and is one of the most rapidly expanding sector of current alternative energy technology. Most existing wind turbines are of the familiar horizontal axis configuration, with spinning propellers directed into the wind by a “tail” or, for larger systems, electronically controlled motors. These “lift” propulsion blades are typically of airfoil shape, like airplane wings or propellers, which rely on the low-pressure lift from the momentum of the wind passing over the airfoil shape. The vertical axis Darrius rotor is also a “lift” device, with its airfoil-shaped “eggbeater” blades. The vertical axis wind turbine (VAWT) pictured above is primarily a “drag” propulsion device (along with “lift” components that allow the rim speed to be faster than the wind speed), which continually diverts the mass of the wind to perform work on the sail. Results from only a few tests indicate that we can increase the low-speed power significantly over the horizontal axis rotating blade wind turbine, largely because we are utilizing “drag” propulsion of a much greater surface area sail instead of just “lift” propulsion from a thin airfoil-shaped blade. According to a Gruman Aerospace research paper on the subject (Tornado-Type Wind Energy System, James T. Yen, Research Department Grumman Aerospace Corporation, published in IECEC „75 Record)*, the increase in power of drag propulsion over lift propulsion can theoretically be thousands of times greater! This fact is little known but extremely important for designing wind energy technology.
The base plate must be securely attached to the mast. We used a tapped aluminum insert glued into the tapered carbon-fiber sailboard mast, as pictured above left. This allowed dismantling of the turbine (which hasn’t been necessary yet). The vanes are attached to the base plate and mast-top with aluminum reinforcing plates, as shown center and right above. On this prototype, only a ¾” folded edge was used to strengthen the vane edges. For maximum strength, run a tension cable or stiff aluminum strip down the leading and trailing edge seams to connect with tension cables to the mast base.