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Build a 15,000 rpm Tesla Turbine using hard drive platters

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Picture of Build a 15,000 rpm Tesla Turbine using hard drive platters
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Here's a project that uses some of those dead hard drives you've got lying around.

In the Tesla Turbine, air, steam, oil, or any other fluid is injected at the edge of a series of smooth parallel disks. The fluid spirals inwards and is exhausted through ventilation ports near the center of the disks.

A regular blade turbine operates by transferring kinetic energy from the moving fluid to the turbine fan blades. In the Tesla Turbine, the kinetic energy transfer to the edges of the thin platters is very small. Instead, it uses the boundary layer effect, i.e. adhesion between the moving fluid and the rigid disk. This is the same effect that causes drag on airplanes.

To build a turbine like this, you need some dead hard drives, some stock material (aluminum, acrylic), a milling machine with a rotary table, and a lathe with a 4 jaw chuck.

Wikipedia has a good review article (http://en.wikipedia.org/wiki/Tesla_turbine), as well as articles about

Nikola Tesla http://en.wikipedia.org/wiki/Nikola_Tesla,
the boundary layer effect (http://en.wikipedia.org/wiki/Boundary_layer),
and Reynolds number (http://en.wikipedia.org/wiki/Reynolds_number)
(which determines if the fluid flow is laminar or turbulent).

I run my turbine on compressed air (40 psi), and it easily reaches speeds of 10-15,000 rpm. While the speed is high, the torque is low, and it can be stopped with your bare hand.

I have more details on my webpage (http://staff.washington.edu/sbtroy/turbine/turbine.html).
 
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Step 1: Make ventilation holes in the platters

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Step 1 should probably be to disassemble some hard drives but I assume that if you read Make, you've already figured out how to un-Make a hard drive.

The easiest way to make vent holes in the hard drive platters is with a milling machine and a rotary table. Center and clamp a stack of several platters to the rotary table and then you can cut any radially symmetric pattern fairly easily. Just be sure that you use aluminium platters because ceramic platters will shatter when you drill into them.

I made two sets of platters; one with a radial array of holes, and one with radial arcs. The platter with radial arcs in the picture was on the top of the stack and took the most damage. The platters beneath it have very little tear-out and look much better.

Step 2: Make or reuse spacers

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The ideal spacing between the platters depends on several variables including the fluid viscosity, velocity, and temperature. You could go through the calculations (http://en.wikipedia.org/wiki/Navier-Stokes_equations) and make a set of spacers, or be lazy and just reuse the spacers from the disassembled hard drives.

I was lazy and reused the spacers that were originally in between the platters. The advantage to this is that they'll have the same inside diameter as the platters. They're about .050" thick where the ideal spacing is closer to .012" but the increased distance doesn't make that big a difference in this case.

Step 3: Make the shaft

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This is just a piece of aluminum stock turned on a lathe. The center diameter is about .98" (which is the inside diameter of the platters) and about 1.77" long (so it will fit in a piece of 2" thick acrylic).

The thinner sections on each end are turned to fit the ball bearings I pulled from a box of scrap.

Step 4: Make collars

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The collars are made from more aluminum stock are wider versions of the platter spacers. The inside diameter is also .98" but they're about .3" thick to hold a #10-32 set screw.

Step 5: Rotor assembly

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Center the platters, spacers, and collars on the shaft and tighten the set screws to hold everything together. I used 11 platters, and 10 spacers. Try to line up all of the ventilation ports. If there isn't enough tension between the two collars, the platters can rotate around the shaft instead of with it.

Step 6: Make the chamber

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This is a 4.75" x 4.75" x 2" piece of acrylic that was bored out on a lathe using a 4 jaw chuck. The intake hole is taped for a 1/4" pipe fitting and all of the other holes are 1/4 - 20.

I used acrylic because it's what I had around and because it's going to be used for lecture demonstrations. You can use metal or even wood. However, if you plan to use steam instead of compressed air, wood might expand too much.

Step 7: Make the side panels (stators)

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The side panels are 4.75" x 4.75" x 0.47" acrylic with untaped .25" holes to screw to the main chamber. The center hole is 0.6" and the counterbore is 0.28" deep.

The two 0.6" holes (one on each side) are the ONLY exhaust ports. The air spirals inwards across the face of the platters, through the ventilation ports, around the air spaces in the bearings (2nd picture), and finally out through these two holes.

However, more exhaust holes in the side panels might improve efficiency.

Step 8: Assemble everything


Step 9: Complete turbine and movie

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Please post (or email me) any questions or comments and I'll do my best to answer them.

Thanks for reading,
Steven
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athan91 year ago

do you know if it can work with a water exit hole?

SammerrA athan92 months ago

It has an exhaust hole. Can it use water? Sure. Will it lose efficiency? Maybe.

Maybe instead of using water or air you can use another kind of gas or liquid that might produce more friction on the platters and create more torque. I really have no idea what... Just trying to think outside the box here....

Increasing pressure, disk spacing, temperature etc all change the reynolds number and therefore the flow. Matching this to the turbine is the difficulty of the design. You can technically make any fluid match the turbine in use but it requires changing these parameters.

Would it be possible to, instead of having the exhausted air be released, have it be forced into another tube to re-use it? (I'm toying with the idea of using this as a drive for an airsoft minigun, with the exhaust air propelling the BBs)

If the turbine is very efficient, the "air" that is being exhausted will have to be re-compressed. Conversely, if you used the turbine to compress air to drive the minigun, then you simply need a power source and strong arms.

Team_Omega1 year ago

Is it possible to add more torque by attaching a gear system, or by adding "fins" to the disks. I realize that it will lose a lot of speed, but will it gain torque?

Adding fins changes the flow and reynolds number. You want more torque increase disk number and diameter, given that all other factors are perfect.

andras.nolsoe7 months ago

How are the discs attached to the shaft? are they welded?

same doubt can someone reply to my mail chilumulapraneeth93@gmail.com

This design uses collars that utilize screws to hold the disk together with friction. Tesla's design uses a keyed shaft. Another method is to use something like a dove tail and collars. This method is very simple and cheap.

RAJNISH AZAD3 months ago

I just want to purchase one of them .

WSF6 months ago

star washer actually helps the rotation buy guiding the air/water to the vent holes as the star extends above the vent holes. If you can see what difference that makes in the rpm.

nerd74731 year ago

I want one!!!

TheStudio71 year ago
Nice, though I stopped reading the comments when some one started the god bs thing. Can we keep reality and stupidity separate please?
maikel22 years ago
a conventional rotary compressor runs more than 100k rpm to develop vacuum to sucks outside air continuously thus compressed it.if this device run at that speed can it become a compressor???
bulsatar2 years ago
For those that don't like math but are still confused: notice that it is basically a closed system (rotationally) from the point of force (the air being blown in). The air circulates in the first platter set until the air pressure is too great and it escapes through the center holes of the platters (ignoring air escaping from the outside edges). This creates a pressure differential between the side of the hole being "pushed" on and the "back side" of the hole, inducing a spin. The pressure differential builds in the next platter layer and then moves out again, and again, and again until it escapes freely from the last platter set's center holes.
Because of energy loss from air escaping around the platters, friction from the bearings and other natural energy sinks, the inside platters exert more torque pressure than the outside ones (math stuffs go here for proof).
Good thing about this design is that you can use some "simple" thermodynamics to have a relatively low pressure, large area front condensed into a high pressure, small area front to get your air pressure from the wind for "free" (think of a properly tuned funnel) to drive an electrical generating motor thingy off of the axle with those new found magnetic thingies...
FlashSC5 years ago
I'd like to ask the silly question here, but, where does the pressed air comes out?
Maybe i missed something...

Thanks for the tuto.

.:FFH:.

You're not!
This IS a stupidly designed device.
the air actually escapes thru the shaft hole.
This is actually correctly designed, with the exhaust escaping through the shaft hole.

The Tesla turbine relies on the boundary layer effect and centrifugal force. The air gets forced to the center and out the shaft hole. An exhaust port on the side would ruin the design of the turbine.
no. CENTRIPETAL. not centrifugal. why does everybody think its centrifugal??
Centrifugal doesn't even exist!
Centrifugal does exist, it depends on your plane of reference. If your plane of reference is the object which has a centripetal force acting on it, there is a centrifugal force.
Nope! :) Centrifugal is merely inertia perceived as a new force.
It's all to do with plane of reference.
If you have a rotating plane of reference, you can have a centrifugal force. Look at the Wikipedia article for it.
Nope! :) Centrifugal is merely inertia perceived as a new force.
FFX2 years ago
Make a good gearbox and put it to a generator which will charge the compressor ;)
Law of conservation of energy prevents this. Gear backlash, for example? Air speed being lost to exhaust?
bart.p3 years ago
great project! have you ever done any test on how much vacuum this thing can generate? im currently designing a turbine that would pump air and have the shaft spun with an electric motor, one of my constrains is the intake size so i need to suck in as much air as possible and preferably compressed it as well
bart.p bart.p3 years ago
if you ave more info about these turbines please let me know, bart.patrzalek@gmail.com
Moe_Tangna3 years ago
Hello!

Can the efficiency be improved by widening the Inlet Port? instead of just focusing on the blades in the center (does that mean the other disks arent getting airflow or something?) wouldnt that mean that more friction (even with the same amount of air) = More Power/Speed/Torque? Also, I cant understand where the exhaust ports are.

This is a great project!
But I cant do it. xD
(3rd world/ too young problems.)
den316a3 years ago
my Question is how much torck does this have can u run a generator off of it?
Techno Dude3 years ago
Hey I wanted to ask u that If u hook it up with a generator how much would it generate and its voltage pleas help
thanatos3703 years ago
If you were to attach a motor to the shaft of the turbine, would that turn it into a pump?
I wonder if you could do me a favor re your tesla turbine, I reached a quantum figure of 17 thou gap between blades (for compressd Air) for a more fluid-like force on the turbines to increase torque. is it possible for you to try this for me.any added expense will be paid by me,or if interested external micro adjustments for simplified cnc made from Corian-bench top and any threaded rod-(zero play acheived) by using human error factor.
RolyB3 years ago
Studying Tesla's Patent plans I see two things that are missing from recent constructs. These are items 26, Circular grooves and 27, Labyrinth packing.
Tesla must have included these for a purpose though he doesn't mention why.
The labyrinth looks like a seal.
I wonder are the grooves a sort of brake or governing mechanism, the fluid gets compressed in the grooves and thus slows the turbine down, perhaps?
I know it must be fun to see how fast the turbine can spin but the practical thing must be to turn that spin into power.
Any ideas on the grooves and labyrinth and why Tesla included them.
jgwiz20073 years ago
http://youtu.be/1n_sB1-JNAY

Check out this Youtube link. I used some of your ideas, and some of my own to build my own Tesla turbine. Hit 30,000 + rpm and still going to add some more hard drive plates...ENJOY!!!
If you connected the input of this to a gravity-fed water supply, could you use it to generate small scale renewable energy: e.g. use it to recharge batteries via a simple (ish) circuit, or would the water be too viscous for this design to work properly?

Thanks
It sounds to me like your suggesting we build a hydroelectric dam but instead of letting the water cycle do our biding we would re-elevate the water? What your forgeting is that your going to have to pump the water back up to an elevated state once it has passed through the turbine. Its an efficiency nightmare lol.
Use it like a regular hydro dam system, then run the spent water into a drain (or plant bed) afterwards. I'm aware thermodynamics might have something to say about pumping the water back up again and trying to get more energy out of it.
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