Why doesn’t everyone use a Tesla Turbine?

Sorry for the confusion on the efficiency. The 65% efficiency (thermodynamic efficiency) I discussed in the video is for "smaller" turbines (under 1000 kW). Modern large industrial turbines can now reach efficiencies of 90% or higher, as a lot of people have mentioned in the comments.

Tesla turbines have a second failing. The disc material deforms the faster it spins. With close tolerances, the outside of the discs eventually impact the housing.

You forgot to mention something very important. When the turbine reaches its resonant frequency. The discs start to vibrate and flex like a tuning fork, and the discs will shake themselves until failure, or they'll smash into the sides of the volute casing.

The comments to this video from actual engineers are half the reason YouTube is such a great platform

Slight correction here, modern hydro turbines are well above 85% efficient. Pumped hydro for instance has a round trip efficiency of about 85% and that includes the pump/motor efficiency, turbine/generator efficiency as well as head losses from turbulence and frictional losses in the pipes. Matching the turbine type (Kaplan, Francis, Pelton) and runner (turbine) blade design with the head and flow is important to ensure maximum efficiency. Similar to a pump a hydro turbine has an efficiency curve with a peak efficiency.

Engineers in the comments coming in hard with the extra context! Love to see it.

I used to do this with our pizza cutters with the sprayer at subway 😂

One of the coolest pieces of engineering I've ever seen was in a 1700s corn mill. They had two main gears running in it. If the gears had the same number of teeth, the same teeth would meet every rotation. So, one gear had 13 teeth and one had 12 teeth. This meant the same teeth would only meet every 156th rotation. This made the teeth wear more evenly.

When a resisting torque is applied to a regular turbine shaft, the weight and viscosity of the fluid drive the blades. The tesla turbine relies solely on the boundary friction of the fluid so any applied torque will drastically reduce the output of the turbine. Learned all about them in fluid mechanics

We use these in wastewater to pump sludge. They work pretty good for that since there's no impeller blades to get ragged up.

The main issue I remember learning about was actually the wear and tear from the spinning speed led to a less economically viable turbine

The one thing not mentioned that is a huge advantage of a Tesla turbine is the fact it has nearly zero pump pulsing and can be great for applications requiring laminar flow.

The reason is that they suck compared to bladed turbines, especially for hydropower. Pelton, Kaplan, and Francis turbines all reach efficiencies of >90%, are less sensitive to debris, and scale much better to large systems. However Tesla "turbines" are regularly used as pumps for highly corrosive fluids.

As an aircraft mechanic of nearly a decade I can promise you a disk you have to pull the entire shaft out to replace is much more work than a fan blade you can unbolt Edit: Spelling

В двигателях, например, турбины должны давать наддув в диапазоне примерно 0,5-2 бар. Больше просто не нужно. На первое место выходят требования к термостойкости, массе, надёжности, стоимости материалов и производства. Далеко не только КПД имеет значение для инженера. Турбины Теслы не забыты. Просто в каждом случае применяется оптимальное решение, отвечающее техническому заданию.

Even though it has a bunch of drawbacks, designing what he did at the time in what was basically his spare time just continues to show how much of a genius Tesla was. Look at how interesting the design of the discs were, the fact that he figured to use air pressure that way is incredible.

i went to school for water supply technology and have a degree. the water industry uses laminar flow pumps. they’re called low shear pumps in the industry and are uncommon but are used. they’re used in low speed applications so the cons of putting the discs under stress are less prevalent. they’re desirable for these applications because it’s pulsation free

Other turbines such as a pelton wheel are > 95% efficient but they don't have the fashionable Tesla name.

Thanks for actually answering instead of being clickbait.

A large failing of the Tesla turbine is the materials required to make a disc that truly benefits from laminar flow doesn’t exist. It must be resistant to any deformation throughout the disc, light enough to not apply extra drag to the liquid that is propelling the disc, and must not swell or compress because laminar flow has a very narrow range of tolerance. Striking the housing or other discs will annihilate the efficiency, of course. Even our best meta materials found today can’t meet the standards required for a Tesla turbine to reach those theoretical efficiency levels.