Can I make this table top fan QUIETER by modding the blades or something else?

Discussion in 'Hydrodynamics and Aerodynamics' started by Squidly-Diddly, Aug 6, 2015.

  1. Squidly-Diddly
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    Squidly-Diddly Senior Member

    Got me one of these and its PRETTY quiet. http://www.target.com/p/lasko-12-performance-table-fan-black/-/A-13992043#prodSlot=medium_1_3

    I didn't install the guard, just because I think it looks better w/out and I'm thinking of butchering up blades in an effort to make it yet quieter.

    Still has more than enough power for my needs. I just like the silent slow breeze you get from ceiling fans, but portable. Also got one of these 'portable' ceiling fans, but for another location. http://www.ebay.com/itm/191283552244


    Questions are:

    Would drilling about 2" dia hole in different spots on each of the blades kill the resonance noise, the same way tire treads aren't the same all the way around to quiet them? Or would that only create MORE noise from more blade edge?

    What about doing something to outside edges of the blades? Shave off approximately same weight of material(to retain balance) but at diff spots to kill resonance noise?

    What about "teeth" or fringes, like a big furry mic cover they use in windy conditions? Some shag carpet on the blades for a kool 1960s pop art retro look?:D

    Maybe just strips of duct tape from blade to blade to break up things a bit?


    How to they reduce noise on fancy billion dollar submarine props and what if anything can I use from that?


    Don't have or really want or need AC here in SF bay area, just need a very QUIET fan.

    Also got one of these I'm hoping to quiet down. http://i01.i.aliimg.com/photo/v1/512089355/Battery_and_USB_powered_mini_desk_fan.jpg
     
  2. gonzo
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    gonzo Senior Member

    Holes will create turbulence and increase noise and vibration. All those additions will also increase turbulence, noise and vibration. Fluid dynamics is a series of courses several semesters long. Cheap fans are not engineered properly, but designed for low cost and adequate performance. The billion dollar submarine props have teams of engineers working for thousands of hours each to achieve results. Many of the high end fans are extremely quiet. You need to pay for the R&D and the quality control in production.
     
  3. NavalSArtichoke
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    NavalSArtichoke Senior Member

    Probably be cheaper to hire someone to fan you with ostrich feathers. I understand those are pretty quiet.

    With the high cost of living in SF, there are a lot of people looking to make a few extra dollars.
     
  4. Mr Efficiency
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    Mr Efficiency Senior Member

    Turn the speed down.
     
  5. upchurchmr
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    upchurchmr Senior Member

    The noise will typically come from the outer tips - traveling fastest.
    I knew an aeronautical engineer who put winglets (like on commercial wings) on a ceiling fan.
    He said it was quieter after he tried about 2 dozen alternatives.
     
  6. PAR
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    PAR Yacht Designer/Builder

    Yes, blade shape (and spacing) will make huge difference in noise. You can make up blades easily enough, 1/8" plywood will do. Symitar shapes would be where I would start. Have fun with it and let us know which was the least noisy.
     
  7. Squidly-Diddly
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    Squidly-Diddly Senior Member

    They have those on the ceiling fans in the newer "24 Hour Fitness" gyms around here. I had no idea it was to make them quiet, since the gyms are pretty noisy. Maybe it also makes them more efficient.
     
  8. Squidly-Diddly
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    Squidly-Diddly Senior Member

    What is the cheap and easy way to make a typical single or three speed household (110v in USA) run slower than lowest setting?

    Something like this? http://www.ebay.com/itm/Single-Turn...e-Control-Ceramic-Disk-Rheostat-/231159550018

    Will it hurt the motor by 'strangling' it? I vaguely remember someone telling it is not good for power tools to run on such long cords that their power is noticeably reduced (Skill saw on 200+ft of cord).


    UPDATE:

    Well I now got one of these fans http://www.vornado.com/circulators/ZIPPI with little FABRIC blades and it is very quiet, strong enough, but most importantly it has a deeper note for what noise it does produce, especially at lowest setting. Sounds more like a 24" fan that is about 30' away across the room and turning somewhat slowly, not sitting on desk blowing in my face. I'm wondering if the slightly uneven fabric kills the resonance. Best sounding and quietest fan so far. Funny, that not mentioned on their site.

    I'm gonna try stretching some gym socks over the blades of the 24" ceiling fan and see how that sounds. Gonna try both wet and dry. Inside out as well to expose the nubby inside to see if it gives a softer sound.
     
  9. Squidly-Diddly
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    Squidly-Diddly Senior Member

    I think I'm mostly after eliminating the "musical" whine, so hopefully just making each blade slightly different will stop it.
     
  10. JSL
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    JSL Senior Member

    I know your situation. Not much you can do about blade noise but You may also have some vibration (humming noise) going to the base and then whatever the fan is sitting on (floor, table, etc) will amplify the noise. Put some folded towel(s) or soft foam under the fan.
     
    Last edited: Aug 7, 2015
  11. Petros
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    Petros Senior Member

    I have considered this on the cheap fans we use at our house during the rear hot days where we live.

    Several things can cause noise: out of blanace fan, loose bearings, irregular blade shape.

    I made our over head fans completely silent by just removing the blades and balancing the outter tips (using a gram scale) and thumb tacks so they were all identical weight at the outboard tip. tip balance is critical.

    You might also try some spray lubricant in the mount, and as noted earlier, setting it on a thin foam sheet to dampen transmitted noise. You might also try stuffing the hollow housing with something to damping the resonance in the housing (foam packing peanuts, threaded newspaper, or spray foam insulation, etc)

    I would also sand off the sharp casting seams off the edges of the blades with fine sand paper. I would not cut or drill the blades, or change their shape or size, it will make the noise worse. This will make it out of balance and will make more noise and likely wipe out the bearing pretty fast.

    Slowing it down with some kind of variable resister would also be helpful, it will not harm the fan at all. the hazard with using really long extension cords on tools and other high demand appliances is the amount of power they draw could over heat the cords. A resister reduces the amount of power flowing through the cord safety, risk of over heat is much lower, and the fan and bearing should last longer as well.

    you can also find a larger fan that turns slower, that will have the least amount of noise. it may take some searching, but more air moving slower, and slower rpms, will reduce the noise and still provide enough air movement for keeping you cool.
     
  12. rasorinc
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    rasorinc Senior Member

    Are you really trying to re-invent the table fan?????????????????? Buy a high quality
    one and use soft earplugs.
     
  13. upchurchmr
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    upchurchmr Senior Member

    I would suggest that most fan designs are copies of 50 year old designs.
    Should be room for improvement.
    Why discourage the next Dyson?
     
  14. SamSam
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    SamSam Senior Member


  15. upchurchmr
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    upchurchmr Senior Member

    If people want to why not?
    You can ignore the thread.
     
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