If you think the design below is not structurally sound, just imagine one of two scenarios:
Could adjusting this turbine's resonant frequencies be as easy as twisting the tuning peg on an electric guitar? (i.e. by adjusting guy wire tension?) And if so, would this offer more choice in other areas, (say) choosing blade materials, airfoil lengths and shapes, etc? Tightening guy wires puts the blades under compression, offsetting the tensile forces caused by centrifugal effects when the rotor is spinning. I don't know if this is good or bad.
Note that since the rotor doesn't need to clear guy wires then nothing prevents designers from choosing tall pylons and placing the rotor high in the air. Though horizontal guy wires and monorail add turbulence, the absence of a tower removes turbulence. If the weight of the rotor is not sufficient for preventing it from toppling off the tower then either make the rotor shorter and fatter or else add a second upside down monorail with wheels to hold it down. Finally, note the relatively large diameter of the monorail may permit a semi-direct drive as shown in the diagram.
Less drag due to guy wires:
Less drag due to guy wires, swept area concentrated near higher winds at top:
Or...
The Fat Tower Darrieus has either no guy wires or else guy wires that are located inside the tower. This allows designers to choose an arbitrarily large diameter for both the tower and the blades since neither of these must clear guy wires. To simplify the drawing, only 2 blades are shown below. An actual turbine would probably have multiples of 3 blades in order to smooth output power. If aerodynamic and centrifugal forces on the blades cause the tower to significantly deform from its cylindrical shape then simply use more blades with a shorter cord.
There is a rule of thumb that says one turbine should be sited at least 3 rotor diameters distance from the next closest turbine. This way if the wind flows through one turbine headed directly for the next then the wind will be re-energized by the time it gets to the downwind turbine. Since tower diameter and blade length for the Fat Tower Darrieus may be chosen to be very large (relative to turbine height) then it is possible that the wind may be either completely or partially re-energized when traveling the distance from the upwind blades to the downwind blades. So what would have been a 1MW Darrieus may produce 2MW if we make the diameter very large (not including the extra power that would result from the increase in swept area). Of course, this benefit does not come for free. Greater thrust would require a more sturdy foundation and tower, greater output would require bigger generators, more blades or blades with longer cords would be required, and so on. Can a computer model be constructed that would determine whether energy revitalization would provide a significant cost benefit?
What if the tower were constructed of symmetrical airfoils and there were no other blades? This is probably ridiculous, but before dismissing this idea I'd just like to say a couple of things:
Variables such as height, width, and number of blades are relatively interdependent in traditional Darrieus designs. One cannot be varied too much with varying the other. These variables are relatively decoupled in the Fat Darrieus Machines described here. The freedom to adjust these variables independently makes me wonder if a linear-programming-like computer model would be able to find a highly cost-effective combination of values for these variables, leading to a very low cost of energy.
If I am the first to think of these designs then I hereby place them into the public domain in order to promote green energy and help solve climate change.
This article published on December 25, 2023. (Merry Christmas world!)
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