


The water turbine designs pictured here are new approaches to lowhead water power generation. Thanks to the instigation of Rod Johnson and preliminary funding from Rich Gover, I designed, built and tested several concept prototypes and learned much about the involute spiral geometry and its potential for harvesting energy. Hopefully, these efforts will receive further funding and development in the near future ~ the world needs new sources of nonpolluting power now.
This page is introductory. To view the final detailed drawings, CLICK HERE.




All of these designs are built upon the involute spiral, which is essentially the unwinding of a circle. Imagine a blue string wound counterclockwise on a spool of radius one. As it unwinds, the end of the string traces out an involute path.






The distance from the end of the involute curve of a full circle of radius1 to its origin is 2pi = 6.28..., the circumference of the circle. The successive unwinding can continue indefinitely, with the distance between successive spiral lines equal to the circumference of the inner circle being unwound.






Involute segments can also be duplicated in a circular pattern, creating pathways between spirals that are nonconstricting.
This and the unique curvature geometry of the involute spiral allow ducts in turbines to capture the force of moving fluids with all the resistance imparted to rotation, not turbulence.






A 3bladed linear extrusion of an involute segment spins very fast in the wind, and also has high speed and torque as an overshot water wheel.




The first set of turbine tests models were designed around these two involute shapes. They were constructed of 6” wide vanes glued in between two plexiglass disks, with steel rod and teflon bearings.





The first test was as an undershot water wheel. Water was pumped into the top rear of this test bed, flowing under the green gate below and through the lower involute blades. Much to my surprise, there was significant drag and not much power. On analysis, the noncompressive nature of water under the upstream vane created an effective damper to the strong rotation imparted at the midstream vane position. This is a very important consideration in designing water turbines vs. air turbines, and applies equally to modified airfoil blade shapes. Turbulent cavitation and drag are created with increased speed, such that the turbine dramatically looses efficiency and can be quickly destroyed by the cavitation.




Neither of these configurations are efficient designs.




Even more resistance is created, for the same reasons, when the turbine blades are fully immersed in the water, both horizontal and vertical.
Q: Will this combination of water turbine below with air turbine above work?
A: The air turbine will work great, but the water turbine will be a dud!
Contrast this to how fast the small prototype spins in compressible air. It will even spin in the wake of a shopvac 12 feet away!




The test rig was then modified to be an overshot turbine, with various turbine mounting options, variable flow directing spillplates, and a variable water gate (green plate top center  set here to 1/4”) to levelout flow of water entering from two hoses at around 12 gpm flow rate.







Click here for a video of testing both turbine configurations in overshot testbed.





This design has the unique property of providing higher torque as more power is being taken from the turbine, due to the greater amount and weight of captured water that is being pulled down by gravity and contributing to the spin of the turbine.
Here are preliminary (not scientifically rigorous) results from the above tests:
•3 vanes 240degree, 1/4" gate = 139 rpm………circumference speed = 218ft/min = 136% of entering water speed •6 vanes 140degree, 1/4" gate = 149rpm……….circumference speed = 234ft/min = 145% speed of entering water •6 vanes 140degree, 3/16" gate = 147rpm……..circumference speed = 231ft/min = 143% speed of entering water (smoother but slower)




The above configuration is diagramed below as a 6vaned 200degree involute 3ft diameter turbine with narrow inlet channel.


After numerous tests, the above was determined to be the most efficient design for a lowhead overshot water turbine. For our test site of 30cu.ft./sec water flow, optimized turbine deployment would be three 42” diameter x 8ft long turbines in parallel, separated by 2ft in stream. This would allow a maximum of 29cu.ft. of water to collect in the vanes as it travels down and through the turbine, or 1,800 pounds of water per revolution assisting in the power generation.
Unfortunately, the chosen site for demonstrating this turbine did not have enough water drop (head) to accommodate this design.







I also performed several tests with the water flowing through a center hole the size of the involute circle. This would be an excellent design for a turbine mounted on the end of a pipe, allowing maximum power capture from the enclosed water pressure. See diagram below:
A vertically oriented turbine produced considerably less torque than a horizontally oriented one, because of the gravitypropelled water loading the vanes.
Flow results for three 240 degree vanes both hoses filling horizontal 1/7 of turbine volume at 1.57 cu.ft./min = 150rpm













Because practical water drop at the chosen site is less than 5 feet elevation, with top of incoming water to bottom of exiting water maximum 7 feet, a vertical axis design was chosen, with six 200 degree involute vanes in an 8ft diameter x 4ft tall configuration as pictured below. Water flows from above, upper right duct (which is covered to compress water into the narrow channel) Outlet below is wider to accommodate slower flow (due to energy extracted from water) in shallower stream.
























The 3ft diameter horizontal axis turbine drawing above is designed to fit within the elevation drop parameters of the site.
STUDY THE OVERALL DIMENSIONS TO DETERMINE IF THIS IS INDEED POSSIBLE! The canal will flow through a constriction, SLOPING FROM BELOW, to accelerate the water to around 100ft/sec at minimum depth of 14”.



5/20/09 ~ a highvolume flow test was conducted pouring from a 5gal bucket to augment the faucet flow.
Total flow through a 1” deep gate valve was 52.7gal/min
ratio of 4' wide x 3'dia turbine to 6" wide x 6"dia turbine = 8 times as wide and 48 times the volume 1" deep equivalent to 8" deep on 4' wide turbine 48 x 52.7 equivalent to 2530 gal/min = 338 cu.ft./min = 5.6cu.ft./sec = 2/5th the flow using only 48" x 6" ratio, = 451 cu.ft./min = 7.5cu.ft./sec = 1/2 the flow speed at max flow = 200rpm, which figures to 400rpm when flow speed is doubled.
This test indicates that the 3’ x 4’ turbine will handle the required flow of 15cu.ft./sec if speed is doubled in the constrictor.
CLICK HERE TO SEE VIDEO OF HIGHVOLUME FLOW TEST


