MIT recently announced its research on toroidal propellers to create quieter drones. That got [Major Hardware] thinking about noisy PC fans. The obvious solution was to adapt the toroidal shape for a PC fan. He was familiar with the idea from similar screws on boats that are commercially available. You can see his tests in the video below.
The shape of the blades on the MIT drones is visible in video and pictures, but there were no available 3D models. [Major] did a design and 3D printed the blades. Watching the comparison with a conventional fan using smoke was pretty impressive. Axial Flow Fans
The fan appeared to work pretty well, but the stock fan worked better. Oddly, the stock fan was also a little quieter overall, but the MIT-inspired blade was quieter at high frequencies. Static pressures were a good bit less for the new design.
Of course, this was a first attempt so there could be improvements that would help. And, as [Major] points out, flying a drone is a different job than cooling a PC, so these tests don’t really negate the idea that the design may lead to quieter drones.
We looked at the MIT drones earlier. If you don’t want to spin a blade, maybe you could move PC cooling air with a flapping wing.
I think the design space is quite different when you’ve got a housing surrounding the fan blade vs. when you don’t. It’s not likely that a blade optimized for one situation works well in the other.
it had to be done though. for science.
It looks, to my eye at least, like he’s used a second A12X25 fan to swap his toroidal rotor onto, which should allow for pretty reasonable comparisons between the two designs; given that an efficiency increase was claimed I would have expected to see a comparison of power drawn.
The cake is still a lie, though.
I feel to make a fair comparison the surface area acting with the air should be adjusted so they plus minus match or at very least the amount of blades should be matched by clipping a few on the A12.
Absolutely! The toroidal shape is all about minimising the effects of tip vortices, but another way to address tip vortices is ducts. Putting a toroidal prop in a duct is unlikely to help.
Wow, it’s 3d printed. you’d think that, in the spirit of open technology they’d share the stl file, but noooo.
I didn’t find the files with the MIT toroidal fans either … why taunt us with the idea and deny the opportunity to print or own?
MIT design has a commercial license unfortunately. Best we can do for now is copy from the pictures. Don”t know why the fan files were not shared, though
Shouldn‘t it be MIT licensed? ;)
I read there was a patent. Find it and you find the spec, right?
you can always design it though. There are plenty of tools around the internet that you can use to parameterise your design – takes a bit of study, but it’s not impossible… I must add, that I do have some experience with aerodynamics and blade design…
Maybe no one asked and the authors didn’t think to post them? Their email addresses are usually easy to find.
Did you read the article thoroughly and understand the full context of who actually designed the fans? If you did, you would know why this is not completely an ‘open source’ project.
The MIT fan is not open technology, and the fan design Major made was not successful as the article clearly states. Why would he share a design that is not correct? The article also clearly states this was his first attempt, maybe he wants to work on the design more before sharing anything or maybe he wants to make sure he is not violating a patent or commercial license of MIT.
How many people have carbon nylon to print in? I wouldn’t PET PLA or ABS print a prop for a quad. Death
Actually LW-PLA is fairly popular for that kind of thing
You take one of the best low noise fan on the market and you compare that to a random 3d printed prototype based on observation… no surprise it perform worst…
doesn’t mean the concept is bad…
I’m surprised he even got to 57% airflow of the noctua with an eye balled design in the first 3d printed prototype. Good job – but way to go in optimizing such a design…
It’s a common rule when modifying a moped/scooter engine in your garage with aftermarket racing parts: if you lose less than 50% of your engine power, the tune-up was a success.
I would have wanted so see/hear the performance of a 3d printed clone of the commercial fan he used to compare. Just to see how much the 3d printing affected the performance.
He has a video where he tested that and it doesn’t make any difference
Yes and the fact vertices occur at the edge but comparing research where there was no shroud or frame around the blades like the drone/ boat propeller wasn’t taken into account. He should have chopped off the square frame. Science is sound, application is the key.
That wasn’t the purpose of his experiment. His entire channel at this point is finding out if there is a better PC fan blade for the A12X25. So removing the motor from the frame would be pointless. He has drones and has made videos about those rotors and fans but they don’t get the views like the pc fans do.
Remove the shroud, toroidal doesn’t need it. Then can be bigger by a ratio of area.
> but the MIT-inspired blade was quieter at high frequencies
Owing to the lower blade count. The blades passing the support struts cause sound pulses, which have harmonic frequencies higher up in the spectrum. The lower blade count is also responsible for the lower static pressure.
I think the title here is VERY misleading.
He tested it, and found it performed less and made more noise.
That said: There are two ways to reduce tip vortices. 1: use these toroidal blades. 2: Put a duct around the propellor. Well… That’s exactly what a fan already does. So there is no point. Second, he just “guessed” at the shape and guessed wrong. Really wrong. His results have no significance.
I think it could be better to compare similar things, 3D print also the Noctua blade and compare the sound between the 3D printed blade. I think the surface conditions has an impact on the noise produce. Anyway, great job on solidworks, I would love to see the performance of this design depending of the angle or the blade number.
the original design is a high solidity ducted FAN the toroidal PROPS are designed for open air and both blade roots should attach at the hub NOW,spitballing,a toroidal ducted FAN,not an open prop,would have a higher solidity,ie,more blades that are narrower with a shape that is appropriate for ducting ie ,very close tip to duct clearances have at it
Barely a ducted fan. Computer fans frequently have tip clearances around 5% of the radius. Which basically performs as an open air fan. The Noctua is pretty good by comparison to most, somewhere from 1-2% from memory. They get it through using glass fiber reinforced blades which deform less as the rpm climbs, so they don’t scrape the shroud.
I’ve tightened up the tip clearances on PC fans and you do get a measurable increase in performance, it stacks well with managing the intake with a bell-mouth and putting a flow-straightener on the back side.
What about using it in the other direction as a windmill?
While some MIT researchers promote share-with-the-world and “open” licenses, it is different outside of CS. MIT has a Technology Licensing Office that helps researchers apply for patents, provides a source of research funding, and helps both startups and established companies commercialize MIT inventions of all sorts. This toroidal drone prop looks like an eminently patentable invention, even though it has been used for marine applications in the past. So look for the patent to come out, be patient, and you’ll be able to buy these blades commercially, and/or you will start to find 3D models floating around to print your own blades. But who am I kidding? I’m not patient, so I look forward to the latter, sooner rather than later. [hint]
While, I do appreciate the review, putting those fans in next to those awesome noctua is an insult to the noctuas. The static pressure is horrible, and the overall airflow is terrible as well in comparison to the noctua. Quiet maybe, but almost worthless in terms of performance. Lol
The good news is he did manage to get the case to liftoff and do a couple laps.
I’m surprised this has only happened now, years ago I was wondering if we could make a quieter propeller for drones, like micro drones.
I thought of a propellor like this because I went down a rabbit hole of quiet propeller tech and how secret it was because of submarine research, and I was like, why don’t we make it a toroid.
Glad to see I had a decent idea
And I am still waiting for my caterpillar-drive PC fan….
What would happen if you doubled the toroidal on itself
I suspect that aircraft turbine compressor design will influence it a bit. Most vanes are compound pitch- Meaning that the leading edge of the vane are of a lesser degree angle than the trailing edge, which deepens down the airflow.
Isn’t the silence impeded by the sharp corners on joining faces? With those smoother over I’d imagine there’d be less turbulence, so less noise and more air moved through the fan because it isn’t impeded by eddies?
his fan design really doesn’t look anything like the MIT closed form propellers that inspired the project…
Those aren’t the ones.
Have you seen the fan showdown? there are some blade designs that perform better than stock. usually extending farther than the original design though.
This did not “make for a quiet PC”, nor did the propeller come from a “spy drone”. Which video did you even watch? It was simply a failed but worthwhile experiment based on MIT research. You didn’t need to post straight up falsities in the title for this to be an interesting video. I watched it before even seeing it here and wondered why you misrepresented it.
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