Our first Tesla Turbine was made in 2005, this is our 4th Tesla Turbine which has been designed with customer feedback and experience making the previous turbines. You requested improved efficiency, increased power and perfect sealing out of the box. This turbine can handle more extreme environments, pressures, temperatures and it can handle steam with ease. No brass comes in to contact with the medium and its aluminium and stainless steel construction is ideal if you are experimenting with ammonia gas.

Who is the Tesla turbine designed for?
After producing and selling Tesla turbines for close to 2 decades we know that the end use is going to be very varied, everything from University lab testing, innovative power generation, but also many hobbyists wanting to produce their own power source. This turbine has been designed to cater to most applications; it can work with steam, water, compressed air or gasses. It’s down to the end user to experiment with efficiencies and tailoring to their particular application. We envisage that customers will make relatively minor changes to tailor the design to their own particular needs, for example if someone was running the turbine with ambient temperature compressed air they could very cost effectively 3D print different nozzles and dramatically improve performance, tailoring the turbine to their pressures and volumes going through the turbine.

Example use cases:

• Someone living on the side of a mountain that was able to produce a significant amount of water pressure from a stream flow down the mountain.
• Numerous Universities have used our turbines to experiment with refrigerant gases and creating a close cycle system.
• Used them to capture waste energy
• Adapted the turbine for extremely low pressure and flow rates. Producing tiny amounts of electricity for extremely specialist applications

Strong Design
The design from the beginning focused on a strong casing that could handle extreme pressures and temperatures. The main casing has a computed failure of around 75bar (1080psi) at room temperature. It has a working pressure (max pressure) of 15bar at room temperature. Working steam pressure has been calculated at 15bar @250C,this will be verified with further testing in the near future (worst case we will fall back for 10 bar for steam).

Seals
Viton O-rings have been used for sealing at 4 points (inlet nozzle, the 2 casing halves, shaft cap and outlet port). Viton seals can handle 200C(400F) continuously and can handle 300C(600F) for up to 48 hours).

Shaft seal
Supplied Coupling Seal We initially planned to provide the turbine with a magnetic coupling and although our tests worked for low power uses, unfortunately the Tesla turbine is too powerful for the current design of coupling. So therefore we’ve fallen back on a sealed design. The seal that we’ve chosen can handle high temperatures up to approximately 250 c and has a steel spring retainer to provide a fairly constant seal on the shaft; this produced no leaks with steam that we were able to measure. Surprisingly didn’t produce too much friction either. The Tesla turbine design is very modular and it is our intention to continue developing the magnetic seal/coupling to potentially offer it as an add-on at a later date.

Labyrinth seal
With the shaft and casing sealed dealt with the only other seal to consider was within the turbine itself. The flow of air/gas/steam/water starts at the circumference flowing in-between the disks through the holes close to the centre and out the back of the turbine. However some flow would be lost through the first disk. A few different Labyrinth seals have been designed. Again these can be tailored to particular applications to improve efficiency. We will open source the part so people can amend and improve. Should be very interesting for those with 3D printers that are using the turbine at low/room temperatures. It is important to note the Labyrinth seal is just to improve efficiency and won’t cause leaks through the casing. You could actually remove it if you wanted to.

Standardise inlet
A ½ BSP inlet thread was carefully chosen. This is commonly fitting used in the UK, All of Europe, Australia, New Zealand and South Africa. It is not used in USA or Canada. However ½ BSP fittings happens to be almost identical to ½ NPT/NPS (pitch same, angle slightly different). Hence compatible with a little extra PTFE. The outlet is a much larger 1 ½ inch BSP fitting designed for unrestricted outlet. This part is changeable and a hobbyist with a lathe could easily make different outlets. The outlet is also removable giving a simple outlet.

Generator and electrical output
As we previous tesla turbines we have using a 3 phase motor with permanent magnets to generate electricity. The magnets in the motor spin rather than the coils allowing for higher RPMs. If it is electrically disconnected or there is no electrical ‘load’ on the motor the turbine is able to spin freely with little friction from the motor. The ‘load’ on the motor can be built up slowly (in testing this was done by switching on a number of light bulbs). As the load is added extra torque is placed on the turbine. If too much torque is applied the turbine will stall.

The supplied generator can produce up to 1400 watts. The turbine should be able to produce more power if it is tailored to a particular application. To 2 to 3 kilowatts seems viable. More maybe possible. The electrical output from the generator is a 3 phase modified sinewave output. The sinewave has a squared top/bottom. This is easy to convert to DC using a very low cost bridge rectifier. The voltage will vary depending on the speed of the turbine. It will be about 1 volt for every 500rpm. Generator is optimal for rpms around 10,000 to 15,000rpm. It will probably handle higher speeds but a different generator will be more suitable/recommended. The turbine has been designed to the generator can be changed.

The generator can be removed to drive something else if you so wish.

Key points

• Increased power (Generator is is capable of 1.4kw, turbine can produce more)
• Greater surface area hence for greater boundary layer effect
• Designed for increase efficiency
• 35x more throughput
• Can handle for higher pressures 300psi+ with air
• Can handle for higher pressures 150psi+ with steam
• Good safety factor built into design
• Better coupling to generator design
• Suitable for close-loop applications
• Casing seals included
• Standard plumbing fittings for inlet/outlet
• Closer to Tesla's original design
• Can be used with compress air, steam, water or many other types of gasses
• Temperatures up to 250C with supplied seals (prolonged burst).
• Seals work at constant temperatures -50°C to 230°C (-15°F to 440°F)
• With prolonged temps up to 230°C (440°F)/
• Hybrid ceramic bearings
• 168mm / 6.6 inch disks
• S304 Stainless steel disks, shaft and spacers
• 1/2 inch BSP inlet
• 1 1/2 inch BSP outlet
• Experimental Labyrinth seal to improve performance
• Labyrinth seal replaceable
• Nozzle replaceable
• CAD design of nozzle and Labyrinth downloadable for tinkering
• Does lends itself to 3D printed test projects