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the trojan fan (media.piefed.social)
submitted 3 months ago by to c/lemmyshitpost@lemmy.world
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trojan fan
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[–] 141 points 3 months ago* (last edited 3 months ago) (91 children)

Its true there is a fan in the base of all bladeless fans, but the fan is smaller then traditional fan designs and moves the same if not more air then traditional fans.

Air is pulled in through the base and forced through a thin slit. This fast stream of air creates an area of low pressure, drawing in and amplifying surrounding air behind the slits.

Because air "sticks" to itself, when you get some air moving (by breathing out, for example), the initial bit of air that you move "drags" some air with it from beside and behind. This is what Dyson calls "air multiplier technology".

Dyson uses this property of air to claim that they only have to move a fraction of air (with the fan in the base) of all the air that blows past you.

Here is a example of how this works, and how you can use one breath to fill a large bag.

https://www.youtube.com/watch?v=rAAelB7nN14

Here is a image of the multiplier effect, from the original intake of air at the bottom. You can see the air is multiplied from behind and infront of the fan.

1000063718

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  • [–] 53 points 3 months ago* (6 children)

    A traditional fan also pulls air from around its blades using the same principal. A bladeless is just a gimmick it has no actual benefits.

    Here's a video on the subject:

    https://www.youtube.com/watch?v=ySSo5PmZZJM

    It turns out, a bladeless fan is even less efficient than a traditional one. It works better, when you remove the casing.

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  • [–] 120 points 3 months ago (34 children)

    still a miss-labeling to call them bladeless fans, just because the blades are hidden. by that logic my beef raviolis are vegetarian (tbf: the catholic church made a similar claim during the medieval ages).

    Bernoulli Fan is not only more accurate, it also sounds much cooler.

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  • [–] 60 points 3 months ago (13 children)

    To play devil's advocate, there are no exposed blades at the point of use. I'd wager people who buy "bladeless" fans are more concerned with aesthetics and avoiding a crying toddler than they are with semantic accuracy. We call Wi-Fi "wireless" even though the router is plugged in.

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  • [–] 29 points 3 months ago (5 children)

    I can stick my peepee into a bladeless fan and not worry about cuts so there's that.

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  • [–] 5 points 3 months ago (5 children)

    Regular fans dont have exposed blades either, there is a mesh over it.

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  • [–] 3 points 3 months ago (2 children)

    catholic church

    Beaver?

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  • [–] 5 points 3 months ago (1 child)

    beavers are also a funny thing: it swims, therefore it is a fish. fish aren't animal.

    i was more referencing things like @arctanthrope@lemmy.world expanded: hiding meat in dough. funny how many strategies they had to cheat a supposedly all-seeing, all-knowing entity.

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  • [–] [S] 36 points 3 months ago* (last edited 3 months ago) (4 children)

    unironically love Lemmy for the explainers you get on a shitpost. Only stumbled on this cause I was looking it up myself. Thanks for the write up :)

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  • [–] 10 points 3 months ago (19 children)

    Smaller fans = more noise

    And why isn't a regular fan getting the "surrounding air" to move too? Is there a subscription for that?

    It's most probably dyson bullshit (the moved extra air is slowing the original air down, or it's magic) marketing.

    Magnets!

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  • [–] 7 points 3 months ago (11 children)

    I got one years ago when they still were a lot cheaper and I must say it's the best one I ever had. It's powerful and so quiet that I can leave it running next to my bed when it's hot.

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  • [–] 5 points 3 months ago (4 children)

    HOW MUCH?

    (Did you pay)

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  • [–] 3 points 3 months ago* (3 children)

    I don't really remember, it's been years. I think it was somewhere between 100-150€.

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  • [–] 17 points 3 months ago* (last edited 3 months ago) (2 children)

    It's also just Dyson's completely overpriced bullshit. It makes weak air flow and has no real benefit for use as a fan.

    Project Farm has tested them a couple different times. They're expensive aesthetic toys.

    *Edit: While I'm on a bit of a Dyson rant; I'd just like to also say that I HATE their hand dryers that some places bathrooms use.

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  • [–] 6 points 3 months ago (1 child)

    Speaking of the dyson. IMO one of the worst fans out there: extremely weak (see measurements on YouTube), extremely loud and very fragile... Have one in the office, and I hate it...

    A classic fan, fraction of the price performs better in all relevant categories...

    Btw. They also create a "bigger" airflow around them so in that regard not better...

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  • [–] 5 points 3 months ago (10 children)

    I've never really understood this multiplayer thing, sounds like a free energy gimmick. You can move more mass at the same speed without putting in more power.

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  • [–] 7 points 3 months ago

    Basically they're trying to claim that the Bernoulli principle is some amazing concept that only they've come up with.

    Their fans do work in the sense they do move more air but it creates so much back pressure that most of that air movement is lost. So you might as well not bother.

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  • [–] 6 points 3 months ago (5 children)

    You're basically trading energy to move higher volume of air. The fan can move smaller amount of air at higher speed, but larger amount at a gentle breeze feels nicer and helps with circulating the air in the room better.

    You could achieve it by taking that exact motor and slapping a bigger fan onto it, but that looks less cool and probably produces more noise? Maybe there's some efficiency differences if the motor is better at spinning fast, but as a spherical cow in vacuum it should be similar.

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  • [–] 3 points 3 months ago

    So it's like a lever, you aren't just magically getting more volume at the same speed without more power, it just slows down when interacting with the outside air, ie conservation of momentum

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  • [–] 4 points 3 months ago (1 child)

    Well in fluid dynamics you don't really make the distinction between liquid and gas. You can model air as basically just a very low viscosity fluid and it works. No one really knows why it works because it shouldn't, air doesn't stick to itself, but if you pretend that it does the simulations still work, even though they're wrong.

    If you look in most physics textbooks even at quite a high level they will tell you that aircraft fly because air sticks to itself, but again, it doesn't. No one is quite sure why aircraft work, no one's all that certain where the lift comes from. But physics textbooks hate to admit that so they just pretend that air sticks to itself.

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