Build a real working turbine from recycled CD's!
This Tesla CD Turbine is based on the Tesla turbine, which was invented by Nikola Tesla in the early 1900's.
Tesla's pumps and motors were unique in that they only used discs, and took advantage of the boundary layer effect. His smallest designs were over 100 horsepower.
This Instructable is an introduction to my recently developed Tesla CD Turbine, which is made from CD's, CD spindle, pipe fittings and glue. This easy beginners version runs on garden hose pressure and is fun for demonstration or experimentation purposes. This same CD Turbine can also be powerful, versatile, useful and dangerous when used with compressed air pressure.
The basic model Tesla CD Turbine shows how the boundary layer idea works to deliver power. The CD Turbine has unique design features such as no moving shaft, no bearings, no seals and uses recycled CD's. It is so frictionless that it can go over 500 rpm just by blowing into it hard!
The advanced model has many cool features, such as the use of neodymium magnets to separate the CD's with the correct gap and a Magnetic Coupler to attach implements, and much more.
My next CD Turbine Instructable shows how to make a Magnetic Disc Pack and Magnetic Coupler for more advanced CD Turbine experimentation. I will develop magnetically-coupled implements that will range from the practical (Generator, SaladSpinner, etc.) to the bizarre ( Skilsaw Blade , Punch Bowl Stirrer, etc).
However, please be forewarned that this turbine on air pressure is not really a kid's toy or particularly safe to operate.
On water pressure it is safe from explosion, maxing out at about 1000 rpm.
The turbine can be run on either water and air pressure without modification. Although this simple turbine can be safely run at one or two thousand rpm on water hose pressure, it can turn tens of thousands of rpm on air pressure.
I must warn you running this turbine on air pressure could be enough to explode the CD's in the turbine and cause injury. To prevent this, regulate the air supply to lower the psi and use a digital tachometer like this one.
If this unit is run on air pressure, precautions must be taken such as protective gear (heavy leather gloves, face shield, helmet, leather jacket & pants, cup(?), etc.), as well as being behind a protective barrier. If the CD Turbine comes apart at 25,000 rpm, sharp CD parts will be impelled literally at the speed of a gun. You are forewarned!
I will be discussing ways to avoid any possible unpleasantness as we go along in these Instructables, but for now...let's have some FUN!
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Signing UpStep 1: Materials and Tools
MATERIALS LIST: (Total Cost about $10.)
1.) 10 (or more) recycled CD's (no labels & no cracks)
2.) CD Spindle with Cover (recycled)
3.) Orbit WaterMaster Extension Nozzle Model 91129 ( Home Depot, $5.95, or try a $1.80 Nozzle from Holland GreenHouse products.)
4.) 1-1/2 inch of plastic straw or tube to fit small end of Nozzle above
5.) Garden Hose Shut-off Valve ($3.50)
6.) 2 feet or more of 3/4 inch PVC plastic pipe ($.50?)
7.) ABS to PVC cement
8.) PVC Pipe Primer
9.) Methylene Chloride (Plastics Shop), for welding polycarbonate CD Discs to each other.
10.) Hot-glue sticks...less than a half dozen
TOOLS LIST:
Gluegun
Hobbyknife
Dremel Tool (optional)
Sandpaper
Notes: 1.) More than 10 CD's may be used for taller CD spindles.
2.) If you can't find the "Orbit Watermaster Nozzle", you could use any plastic or brass water nozzle, such as the Holland GreenHouse brand Plastic or Brass Power Nozzle. Or simply use a combination of pipe fittings down to a 1/8 inch nozzle, and adapt with hot-glue to the CD Cover.
1.) 10 (or more) recycled CD's (no labels & no cracks)
2.) CD Spindle with Cover (recycled)
3.) Orbit WaterMaster Extension Nozzle Model 91129 ( Home Depot, $5.95, or try a $1.80 Nozzle from Holland GreenHouse products.)
4.) 1-1/2 inch of plastic straw or tube to fit small end of Nozzle above
5.) Garden Hose Shut-off Valve ($3.50)
6.) 2 feet or more of 3/4 inch PVC plastic pipe ($.50?)
7.) ABS to PVC cement
8.) PVC Pipe Primer
9.) Methylene Chloride (Plastics Shop), for welding polycarbonate CD Discs to each other.
10.) Hot-glue sticks...less than a half dozen
TOOLS LIST:
Gluegun
Hobbyknife
Dremel Tool (optional)
Sandpaper
Notes: 1.) More than 10 CD's may be used for taller CD spindles.
2.) If you can't find the "Orbit Watermaster Nozzle", you could use any plastic or brass water nozzle, such as the Holland GreenHouse brand Plastic or Brass Power Nozzle. Or simply use a combination of pipe fittings down to a 1/8 inch nozzle, and adapt with hot-glue to the CD Cover.
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Funneling just doesn't work with wind turbines, its relates back to the equation that only 59% of wind energy of a given swept area can be harnessed. This is largely due to airs high viscosity, it bounces around and creates turbulence within a funnel, a small amount of funneling will improve performance slightly but large funnels actually make turbines less efficient, as they create drag and turbulence rather than allowing a clean stream of air onto the turbine. The amount of compression you could get with funneling would be minimal at best.
I do however believe that using wind turbines to compress air via a piston or pump is completely feasible and would like to look into doing this myself.
Not a great deal of practical application, in most real world environments.
If I saw a video of this turbine out doors in a light to moderate breeze, I be more inclined to beleive it has potential. However no such video's exist. I'be made a coupe of lenz2 turbines, with a good degree of success, and recently came across the "canstien" or " c-rotor" which is a variation of the lens 2 design. I plan on building one of identical proportions to one of my. Lenz2's will post an instructable in the near future to compare the two designs.
You can see some of my turbines on my youtube channel wildwabbit74
:)
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http://www.youtube.com/watch?v=Vyvf7iyi-wM
Your calculations and formulae are good, but there are some hints and important points.
1.) The height of the disc pack is not as critical as it seems. You can use almost any number of discs you wish. From around 6 discs, up to 25 discs, is generally a good number to use.
Understand that if the inlet nozzle is relatively high in the case, the whole disc pack will rise to the top of the case when the turbine is running anyway.
2.) More discs do not necessarily mean more power. The inlet velocity/pressure of the fluid is most important, and the higher speed particles can only cover so many of the discs, depending on volume of fluid and shape of inlet nozzle.
3.) If the turbine is used with water pressure, the top magnets are usually larger for better magnetic coupling. They stick out, (without a CD on top) to be closer to the top of the case. So you have to add their height to your equation.
4.) The magnets form a bearing surface at the inner top of the case, and skim along barely touching the case when it's running due to the fluid bearing effect. (note: if the turbine is used for compressed air pressure, then larger top magnets can't be used because the rpms are too high.)
5.) The centre post gets drilled for fluid exit. Keep the holes toward the top of the post exactly where the CD's will be rubbing when they rise up to the top under running pressure.
6.) The type of CD case is important, as some of them are virtually impossible to seal properly to be able to build up pressure internally. I use the older Memorex cases with a thick bottom so the hot-glue will hold better.
Good luck and let me know how it goes!
May you continue to ponder the mysteries of the Tesla Turbine for years to come!
What happens is, if the turbine is working properly, even 15-20 psi is enough to send the discs over 10, 000 rpm. With excessive rpm, the CD discs can fracture, and sharp shards come through the side of the case, with possible injury or death.
I have taken turbines up to 14,500 rpm, but they will usually break before that. The magnet spacers limit the max rpm. Plain CD discs go up to 25,000 rpm before exploding.
The CD case itself can take up to 120 psi without exploding...as long as it is somewhat gradual. I did blow up one turbine by too rapid of an increase in pressure! ( see "Tesla CD Turbine Blender Bursts On Kitchen Table", http://www.youtube.com/watch?v=EXo3e58rZ7U )
CD discs with magnets are limited in rpm to about 8000-10,000 rpm. Even then, the disc could shatter at any time.
Cutting holes in the discs could lower the safe rpm even more.
When a disc blows at 15,000 rpm or more it literally explodes and sends sharp shards in all directions. See this site, "The Case Of The Exploding CD-ROM Record",
http://www.qedata.se/e_js_n-cdrom.htm
Another helpful hint...When building a turbine case or parts use polycarbonate or aluminum or steel, etc. Don't use acrylic. Here's why: http://www.youtube.com/watch?v=Hsls5ZPCUnE
So, the idea is to keep the revs down and play safe with protection. New materials such as carbon nanofiber ceramic for discs, and lighter, stronger magnets will soon make the magnetic Tesla Turbine a greater reality.
Tesla Tornado Tube is an example of a magnetically coupled Tesla disc pump.
http://www.youtube.com/watch?v=eVOYKsUcPO4
The Punch Bowl SuperStirrer is a fun Magnetically-coupled stirrer with a Tesla CD Turbine coupled to a Tesla Pump:
http://www.youtube.com/watch?v=q3v_1upRdtA
"Blender Bursts on Kitchen Table" is a magnetically-coupled blender experiment.http://www.youtube.com/watch?v=EXo3e58rZ7U
More on that blender...http://www.youtube.com/watch?v=tIWPsckaiCw
There's more on this idea at my SinkScience playlist:
http://www.youtube.com/user/MrfixitRick#grid/user/DBEC3A3C414EB39F
Here is a movie someone made of the Tesla Fan:
http://www.youtube.com/watch?v=0I6VUkw_Fg8
Build it, and let me know!
Check out wikipedia for "Tesla Turbine".
The Tesla pump is found in US Patent # 1061142 ~ "Fluid Propulsion"
http://www.instructables.com/id/Tesla-turbine-from-old-hard-drives-and-minimal-too/
http://www.instructables.com/id/Build-a-15%2c000-rpm-Tesla-Turbine-using-hard-drive-/
How would you go about getting the magnets to stick?
I generally use a good quality grade of Crazy Glue. The magnets need to be cleaned with solvent and scuffed for best adhesion.
For the larger drive magnets I sometimes use Marine Goop in addition. For example, I put a 1/4 inch bead around the base of the 1/2 inch magnets to support them.
Goop pulls tighter when it sets up after a couple of days, and sticks really good to both surfaces.
Methylene Chloride works for gluing polycarbonate, but not for the nickel plating of the magnets ;)
Also, the polycarbonate CD discs are coated with a resin, making poly solvent less effective.
Additional water pressure will increase the turbine power and rpm's sufficiently to drive the alternator properly.
The engagement mechanism you mention might be useful if the turbine was tuned for maximum torque at a specific higher rpm, but usually there would be no advantage (other than flywheel effect) to "spinning up" the turbine first.