Air Powered Tesla Turbine

This photo shows the Tesla pump on the right and the Tesla turbine with gearbox on the left. The pump was my first attempt at exploring "boundary-layer" technologies. I decided to build these models using layered-object-modeling techniques (LOM). The pump was designed and built in less then four hours. The pumps' performance is poor in air because it is so small. I've never tested it in water, but I'm sure it would be more impressive. Blowing shop air into the pump quickly shifted my attention to the turbine.

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The turbine was my second design. I have since made several design revisions improving efficiency. The turbine as presented generates roughly 150 watts (0.2 HP) running an 8" x 4" propeller at 10,500 RPM while consuming about 3.7 SCFM @ 40 PSIG. The rotor is running at twice the prop speed: 21,000 RPM. I don't actually know the airflow into the turbine, it was estimated by the volume, pressures and cycle time of the air compressor. Worst case: output power (150 watts)/input power (1725 watts)= 8% efficient. Not too bad considering that includes the two stage air compressor! More testing will be done and the results will be published here and submitted to the Phoenix Turbine Builders Club website:






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Here are the terms of this offer:
The kit is sold as a Static Display Model Kit ( YOU CAN NOT apply air pressure to make it spin).
The gearbox and propeller will NOT be included.
The air inlet port will NOT be included.
The kit must NEVER be assembled with adhesive.
Any modifications to the components or kit as provided will void any and all
warranty and will thereby release OBI Laser Products (Robert O'Brien) from
any and all liabilities relating to the product. Any person who modifies
this product in any way assumes any and all liabilities relating to the
product. NOTE: Only 8 of these were sold. They are no longer available.

TT-SDM Related Downloads: 


TT-SDM Assembly.doc


New Information: 7/29/04

OBI Laser Products' Air Powered Turbo-Generator

We have recently developed a new Turbo-Generator


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The system is illuminating three automotive headlights as a dummy load.
At present, this prototype has achieved the following peak performance:
Max Cont. Power:    153 watts = ( 7.7 VAC @ 11.5 AAC) = {0.2056HP}
Air Flow:                 4.7 CFM(ind.) @ 65 PSIG = (0.6536 HP)
Peak Efficiency:      31% (0.3145) = {0.2056 / 0.6536}
Note: Theoretical HP in compressed air = 0.2267(cfm)*(((PSI/14.7+1)^0.283)-1)
           taken from: page 11, "Pocket Ref" by Thomas J. Glover, ISBN 1-885071-33-7
Here is a typical run ( 5 to 20 minutes):
Input Power;
Input air pressure: 65 psig
Input air flow:        4.7 cfm(indicated, = 10.94 SCFM)
Theoretical input power: ~0.6536 HP (487 watts)
Output Power;
Rotor Speed:    30,000 RPM
Output frequency: 1 kHz ( 2 cycles per revolution)
Output voltage:    6.7 VAC RMS per phase
Output current:    12.0 AAC RMS per phase (12 x 1.732 = 20.784 amps total)
Output power:     6.7 * 20.784 = 139.3 watts (actual power into load)
System efficiency: 139 / 487 = 28.6% !!!
Here is what happens when the rotor fails!
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I am proud to say that the housing withstood the failure perfectly, it is even re-useable.
The turbo-generator has since been tested with several rotors of various materials.
Here is a short video (1.6MB) of the turbo-generator running: (select Windows or RealPlayer)
Download File
Download File
Here is a longer version (4.5MB) with more information:
Download File
Download File
This generator is available for experimental and educational purposes, Starting at $350 US. Contact us for details.
*** New ***  as of 12/29/04
OBI Laser Products' Stainless Steel Turbo-Generator
We have recently shipped the first prototype stainless steel turbo-generator (s/n# SSTG-001) to a University. They will be able to fully monitor the turbines' operation with plenty of gas supply and instrumentation. SSTG-001 was designed to run in an Organic Rankine Cycle system for waste heat recovery experimentation. The 12 oz. steel rotor is identical to the original design (TT-SDM). The rotor is supported upon four, open-race, ABEC-3, stainless steel ball bearings. It is rated for 55,000 RPM. The generator is an Aveox 36/15/2 brushless, three-phase AC motor operating as a generator. It is not the ideal choice for the generator but it was readily available and inexpensive. The motor was designed for model aircraft use with lots of air cooling, it should be fitted with a liquid cooling jacket and thermocouples.
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This new turbo-generator has achieved >38% system efficiency, producing 252 watts of electricity while consuming 7.4 cfm @ 50 psig of compressed air. The generator itself is less then 80% efficient, therefore: a simple Tesla type boundary layer turbine can easily achieve 45+% kinetic efficiency.
The fact the the air was rather moist during the peak run, probably explains the ~10% gain in efficiency when compared to the nominal runs. This means that the SSTG-001 should perform very well in the Rankine cycle system. Additionally, the design of the acrylic turbo-generator has already demonstrated an 8 to 10% gain over the original design.
SSTG-002 is presently being developed to operate in steam with sealed, oil lubricated bearings. It will also incorporate a liquid cooled generator.
Here are some videos of the stainless steel turbo-generator. Sorry about the quality, if your media player has an audio equalizer then you can curve up a peak around 250Hz to help hear my voice. - ROB
This is a brief overview and then a nominal run:    TGSS Overview and Run
This is the peak run:   SSTG Peak Run '04
This is a review of the test equipment:   Download File
This generator is available for experimental and educational purposes, Starting at $750 US. Contact us for details.
*** New ***  as of 08/02/05
Possibly the worlds largest collection of Tesla turbo-generators:
We have recently completed a shipment of twenty five Tesla Turbo-Generator Demonstration Units. They are available for purchase from: .
Here's a video of the demo unit in operation: Download File

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