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Richard Gideon's Continuing Experiments in Disk Geometry Improvements

January 2003

This is the sort of activity we want all our members to get into. And now we're making it easy by providing our Experimenter's Tesla Turbine. Since these Tesla turbines can be powered immediately on compressed air, it is the ideal R&D platform. (We operate our unit intermittently on a very small compressor, so anyone can achieve significant results like ours.)

Here is Richard's report:

(For background, see the December PTBC article: Experiments in Disc Geometry Improvement by Richard Gideon).

You mentioned it would be interesting to compare my data with a standard Tesla design. I agree. Therefore I built a stock Tesla rotor. Again the results are below.

I made three test runs. I started with a rotor without spacers knowing that because my perfectly flat smooth polished discs were anything but perfectly flat smooth and definitely were not polished and that there would probably be a difference in speed. There was. The new rotor ran about 400 RPM faster then the first one. So with that as a new reference point, I then adding the spacers (12 on the perimeter and 6 in the middle) the speed increased almost 1000 RPM. After that I then cut a saw tooth edge on the center discs, this produced an additional 500 Plus RPM.

NEW TEST DATA

	RPM (no load)
NEW DISC WITH NO SPACERS	3990
NEW DISC WITH SPACERS (STANDARD TESLA) {+975 RPM}	4965
NEW DISC WITH SPACERS AND SAW TOOTH EDGE {+540 RPM}	5505

Finally I ran this last test. I started with a regulated 30 PSI (the lowest that I could go and still have the turbine start and run). I then recorded the maximum speed that it was able to obtain at that pressure. I then increased the pressure in 5-pound steps and recorded the following readings. Unfortunately 75 pounds was the maximum sustained pressure I could run before my compressor ran out of breath. The result is virtually a linear increase in speed as the pressure increased. Not quite what I expected. Any thoughts on this?

6-INCH DIAMETER ROTOR

PSI	RPM
30	360
35	660
40	960
45	1260
50	1500
55	1800
60	2040
65	2400
70	2640
75	3000

Sincerely,

Richard Gideon

Spotteddogs@iwic.net

Richard -- Thanks for sending the data. In answer to your question about linear increase in speed with incremental increases in pressure -- since the back pressure caused by centrifugal force on the gas increases linearly with rotor speed, the incoming gas pressure would also have to increase proportionately to oppose the back pressure.
A couple of other interesting facts to keep in mind:

Boundary-layer turbines are nearly powerless below 50% of their maximum speed.

Also, maximum torque is realized at 50% maximum speed and decreases linearly as maximum speed is approached.

Efficiency begins at 50% and increases linearly towards maximum speed. Horsepower begins at 50% and increases only 6% at maximum speed. One last thing -- your 6-inch turbine should spin at 35,000 RPM at maximum. -- Ken