Fundamental Form-s

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Hyperboloid star-weaving for venturi shroud wind & water turbines


Hyperboloid star-weaving to generate venturi shroud for wind turbine & water turbine

A hyperboloid of revolution is generated by rotating a straight line that is inclined at a compound angle to the central axis of rotation.  In the above model, visualize the thick blue “line” being rotated around the central axis to define all the intermediary lines defined by the stretched strings.  Observe that there is a complimentary line which is a mirror of the first line, which likewise rotates to generate the 3D venturi curve.  If this curved surface is made into a continuously smooth surface, the shape looks something like the picture below:

hyperboloid shroud generated with straight lines

This shape obviously has the property that a fluid flowing through the middle of it will be accelerated at the central constriction.  This is useful for concentrating the energy of flowing air or water so that more energy can be extracted from a higher-speed turbine.  There are several advantages to this.  According to mathematical analysis, wind or water power is proportional to the cube of the wind or water speed, or doubling the speed gives 8 times the power.

Additionally, this particular shape of a venturi has some very useful properties.  Consider the shell to be paper-thin, with the fluid flowing past it both inside and outside.  Because the curved surface is defined by straight lines, if the wind or water enters the turbine in a vortex spin, which it automatically does entering a turbine, if it follows the straightest path with least resistance, it will automatically flow along the generating straight lines, both inside and outside the shell, with minimal impedance to flow.  Therefore, the ratio of the large opening to the small constriction will determine accelleration.

Hyperboloid wind shroud-5weave

Note that there are 10 stiff wires supporting the woven hyperboloid, which form a 5-pointed star from above.  This geometry creates a constriction of 10.5 to 1, which would theoretically accelerate a 10 mph wind to 105 mph, or a 1 knot water flow to 10 knots.   Likewise, a 7-weave, as pictured below, has a constriction of 20.25 to 1.  In this way, it is possible to achieve any fluid acceleration ratio by varying the weave pattern.  This is theoretical without friction, and i have not verified these figures emperically, but laminar flow should prevail up to sub-sonic speeds.

Hyperboloid wind shroud-7weave

Furthermore, the straight lines that form the hyperboloid curve can also form the curve of the internal turbine blades, as pictured below for a hyperboloid based on a 6-pointed star weave pattern.  Note model is missing two of the six blades.

hyperboloid 6-star-weaving-turbine blades
hyperboloid 6-star-weaving-turbine blades2

Construction for a water turbine would most probably be best with stretching fiberglass roving and woven strips along the generating lines and smoothly weaving or overlapping to create a thin smooth surface of great strength.  The same technique can be used for wind turbine construction, using carbon fiber for light weight and a wind-directional vane to orient into the wind.

Other applications present themselves as useful avenues of experimentation.  A venturi shroud of great accelleration construction would produce a low-pressure at the region of greatest constriction, which could be used to pump water in stages to holding tanks of increasing elevation, with no moving parts but a series of pressure-actuated valves.

This invention is now in the public domain and is no longer patentable as of June 29, 2009.  In fact, I published this invention in the mid 70’s in Alternative Sources of Energy Magazine, so it has been in the public domain for around 40 years!

All I ask is that you share your experience with me in applying this technology. I will post your pictures and share your insights on this webpage, that others might improve the design and we all will benefit.

Larry Dobson