A Turbine With No Blades: Building a 7,000 RPM Tesla Turbine

Overview

What happens when you try to build a turbine with no blades at all?

More than a century ago, Nikola Tesla proposed exactly that: a radically different turbine design that replaces traditional blades with a stack of smooth rotating disks. Instead of pushing against blades, the working fluid flows across the disk surfaces and transfers energy through boundary-layer drag. This concept, known as the Tesla turbine, is simple in theory but surprisingly challenging to build in practice, since performance depends heavily on factors like nozzle angle, disk spacing, and keeping the disk stack precisely aligned on the shaft.

Beyond its unusual design, the Tesla turbine offers several practical and environmental advantages over traditional turbines. Because it has no blades, there are far fewer moving parts, which means less mechanical wear, lower maintenance requirements, and a longer operational lifespan. The simple construction also makes it relatively inexpensive to build and easier to manufacture at small scales. Our build demonstrates this directly. We constructed the entire turbine using inexpensive and scrap materials, including PVC pipe for the housing and off-the-shelf bearings and bolts, while still achieving 7,000 RPM. From an environmental standpoint, the Tesla turbine can run on a wide range of working fluids, including steam, compressed air, or even low-grade heat sources that would otherwise go to waste. This flexibility makes it a promising candidate for small-scale energy recovery applications where capturing wasted energy would be impractical with conventional turbine designs.

For this project, my friends and I designed and built a small Tesla turbine from scratch to explore how effectively a bladeless turbine can convert airflow into rotational speed and electrical output. The turbine uses a stack of five closely spaced disks mounted on a central shaft and is driven by compressed air. We then connected the shaft to a small generator to measure how the turbine’s rotational speed translates into voltage.

Along the way, we experimented with several important design variables, including nozzle orientation, the spacing between disks, and minimizing friction in the rotating assembly. These small details have a large impact on performance because the turbine relies on smooth, high-speed airflow across the disk surfaces rather than direct blade impact.

The final turbine reached roughly 7,000 RPM and generated about 8 V using a small DC dynamo. In this Instructable, I’ll walk through the full process of designing, building, and testing the turbine, and show how Tesla’s unusual bladeless design can still achieve impressive rotational speeds.

All the parts and components of the turbine were designed using Autodesk Inventor. All the files have been attached to their respective steps however I am also attaching an entire Google Drive with all the files here:

https://drive.google.com/drive/folders/1fJGRaxKuNwwfbp8snjMLU2pM1LIkelKK?usp=sharing

How it Works

The Tesla turbine operates very differently from traditional turbines. Instead of using blades that are pushed by fluid, it relies on boundary-layer drag.

Compressed air enters the turbine through a tangential nozzle, meaning the airflow travels along the outer edge of the discs rather than directly toward the center. As the air moves across the smooth surfaces of the discs, friction in the thin boundary layer causes the discs to begin rotating.

Because the airflow is already moving in a circular path, it gradually spirals inward toward the center of the turbine. The air eventually exits through the holes near the center of the discs and through the exhaust openings in the side panel.

This spiral motion allows energy to transfer smoothly from the airflow to the discs, enabling the turbine to reach high rotational speeds even without traditional blades.

Design Decisions

Several design choices had a major impact on the turbine’s performance:

Disc spacing

The spacing between discs must be small enough for boundary-layer drag to transfer energy effectively. In this design, 2 mm washers were used as spacers between the discs.

Nozzle angle

The inlet nozzle was positioned so the airflow enters tangentially to the disc edge. This allows the air to spiral smoothly inward rather than striking the discs directly.

Number of discs

The turbine uses five discs, which provided a good balance between airflow resistance and energy transfer.

Disc rigidity

Plastic and aluminum discs were initially tested but proved too flexible. 1 mm stainless steel discs maintained their shape better at high rotational speeds.

Disc Holes

Disc holes are necessary for proper airflow, however too many weaken the discs structural strength and too little trap air between. After experimenting we finalized on a design that orients variable diameters in a way that efficiently uses the space.

I also want to credit CrazyMachinist94 and his Tesla Turbine design, from which we took quite a bit of inspiration.

Stainless Steel Sheet (1mm thick) to cut the discs out of : Note- you can use other materials as well but I found this worked best

Nuts and Bolts x 8 : Nut Length: 13cm Diameter 1cm + washers for them x 16

Metal Shaft (Stainless Steel: 15mm diameter)

2mm Washers

Acrylic Sheet (1cm thick) to cut the side panels from

15mm Bearing x 2

11cm Diameter PVC pipe

Silicone Sealant

Some form of compressed air: We used compressed oxygen at 50psi

Bolts of 15mm diameter x 2

Access to Machining Tools like CNC and a Lathe

For the discs, we experimented with several disc materials and hole configurations before settling on our final design. Plastic was too weak under load, and aluminum bent too easily, so we chose 1mm stainless steel. For hole spacing, 12 holes of the same size weakened the material too much, 8 holes couldn't have enough airflow, causing disc deformation. We settled on 6 holes of one size and 6 of another size.

The discs were CNCed out of a 1mm thick stainless steel sheet. Each disc by itself is 88.9mm in diameter. We used 6 10mm holes 60 degrees apart and 6 5mm holes 60 degrees apart, which enables good airflow through a sizeable amount of holes without creating very small gaps that weaken the integrity of the discs. All these holes are 25mm away from the central hole, which is 15mm in diameter. We cut a total of 5 discs.

For reference, I have attached a .ipt and .dwg file of the part

The housing holds the turbine assembly and directs compressed air into the discs. For this build, we used a section of 110 mm diameter PVC pipe, which is inexpensive, easy to machine, and rigid enough for this application.

First, the PVC pipe was cut to 60 mm in length. This dimension was chosen so that the pipe could fully enclose the stack of five discs while still leaving space for the acrylic side panels.

Next, an air inlet hole was drilled in the side of the pipe. The goal here is to introduce air so that it enters the turbine tangentially, meaning the airflow should move along the outer edge of the discs rather than directly toward the center. Tangential airflow is critical in a Tesla turbine, because it allows the air to spiral inward across the disc surfaces and transfer energy through boundary-layer drag.

After drilling the inlet hole, an air intake nozzle was attached and sealed using silicone sealant to prevent air leakage. When positioning the nozzle, try to angle it so the airflow follows the outer curve of the discs as closely as possible.

OPTIONAL: We spray painted the housing a navy blue color for aesthetics

for reference, I have attached a .dwg and .ipt file of the part

The shaft holds the entire disc stack and transfers the turbine’s rotation to any attached load, such as a generator.

For this project, the shaft was machined from stainless steel and turned on a lathe to a 15 mm diameter.

After turning the shaft, it was cut to a final length of 170 mm. The shaft was then threaded, allowing nuts to be screwed onto the shaft. This makes it possible to clamp the disc stack tightly together while also making the assembly easy to disassemble if adjustments are needed.

To assemble the disc stack:

1. Thread a nut onto the shaft.
2. Slide the first disc onto the shaft.
3. Place a 2 mm washer after the disc to act as a spacer.
4. Repeat this process for each disc, alternating between discs and washers.

The washers maintain consistent spacing between the discs, which is important for proper airflow in the turbine.

Once all five discs were installed, a final nut was tightened onto the shaft to secure the entire stack in place.

for reference, I have attached a .dwg and .ipt file of the part

The side panels seal the turbine housing and hold the shaft bearings in place.

Both panels were machined from 10 mm thick acrylic sheet. Acrylic was chosen because it is easy to machine and allows the internal structure of the turbine to remain visible.

Each panel contains a central hole for the shaft bearing. The bearings support the shaft and allow it to rotate with minimal friction.

One of the side panels also includes several exhaust holes. These holes allow air to exit the turbine after it has passed across the disc surfaces and moved inward through the center holes in the discs. Without these exhaust openings, pressure would build up inside the housing and reduce performance.

Additional holes were drilled near the outer edge of both panels so that they could be bolted together. These bolts compress the entire assembly and keep the housing sealed.

As always, I have attached a .dwg and .ipt file for reference.

Once all components are prepared, the turbine can be assembled.

1. Start by installing the bearings onto the shaft.
2. Insert one end of the shaft into the center bearing hole of the first acrylic side panel.
3. Carefully position the disc stack inside the PVC housing.
4. Place the housing against the first side panel and seal the joint with silicone sealant to prevent air leaks.
5. Slide the second side panel onto the other end of the shaft.
6. Align the bolt holes on both panels.
7. Insert the eight bolts through the panels and tighten them evenly to compress the assembly.
8. Apply silicone sealant around the edges of the housing to ensure the system is fully sealed.

At this stage, the turbine should spin freely when the shaft is rotated by hand. If it does not, check for shaft misalignment or discs rubbing against the housing.

To evaluate the turbine’s performance, the shaft can be connected to a small DC generator or dynamo.

As the turbine spins, the generator converts the rotational motion into electrical voltage. By connecting a multimeter to the generator terminals, the output voltage can be measured while the turbine is running.

In our case we connected a dynamo generator by drilling a small hole in the shaft and connecting it to the motor. We then connected it to a voltmeter and a light to demonstrate the output. The result was that, when powered with compressed air at approximately 50 PSI, the turbine reached roughly 7,000 RPM and generated about 8 volts through the attached dynamo.