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

Yes, that is true.

You're using the wrong kind of fan, try a centrifugal or a cross flow type.

https://en.wikipedia.org/wiki/Mechanical_fan

Or......

 

I'm not sure the world is ready for a $600 table fan.

 

Given the price of boats I don't know why not
Would you ever have thought of $10K bicycles?

Anyway, If you come up with a design it would not be much to injection mold the shape to make 10,000 of them and spread out the cost.

Its the one of a kinds that cost so much.

Anyway, quieter has already been done, for less than $600
http://www.hsn.com/products/dyson-am06-air-multiplier-12-bladeless-fan/7751897

 

$10K bicycles are way more ridiculous than $600 table fans. You can't do much more on a $10K bike than you can a cheap Schwinn.

Shhhh! Not so loud! You'll burst Dyson's bubble!

 

Well, I can't do much more on a $10K bike, but I have a friend who can.

 

I hear(pardon pun) there are reasons why Dyson doesn't include simple decibel level VS air flow tests for his fans VS the sub-$20 competition. My brief review was that a Dyson fan on high puts out and sounds about like a $20 fan on low, and a Dyson fan on low might be a LITTLE quieter than a $20 fan on low.

So far the $15 "ZIPPI" with its decidedly low tech, non precision, fabric blades seems best, partly because of the lower musical note it puts out, and the larger component of White Noise VS whine.

 

The amount of noise reduction for a given amount of work is surprisingly low.
In collage I helped a team reduce the noise on a paper shreader (professional size).

We reduced the noise a great deal on the decibel meter - about an order of magnitude. I don't remember the exact readings.
The manufacturer thought it was not enough to bother with.

Take what you can get.

 

Agreed, things can be done, though the questions are equally obvious, such as is this worth the trouble. Mass produced blades tend to be "clsoe enough" in terms of sound, balance, shape, volume, etc. All of this issues can be addressed, with some improvements seen with each.

Automotive water pump fans use an asymmetric blade spacing to help control the noise. Blade plan form and sectional shapes can make huge gains. Balancing should go without saying, so play with well balanced shapes first and see how much you get.

 

You can always try these mods to the blades

http://www.windpowerengineering.com...des/whale-fins-influence-wind-turbine-design/

 

I silenced a fan by putting it on soft rubber pads.

 

An off switch is the most effective noise reduction system, though much effort can be made, on just about any common fan blade, to reduce noise. Blade speed, shape, housing shape, etc. all can greatly reduce noise. I once took the enclosure off a box fan, to make an exhaust fan for a paint booth and noticed a significant noise reduction. Squidly, Make up some blades, try "ducting" the enclosure, etc. and you'll soon find major improvements. Have a look at the props used on submarines for a good starting point.

 

I've noticed steel, belt driven radiator fans are radically asymmetric in the spacing of the blades, but still balanced. I'm assuming that is for noise reduction similar to tire tread. So IMO indoor comfort fans SHOULD be asymmetric.

I don't recall plastic electric radiator fans being asymmetric, or at least not a noticeably as the steel ones found on typical rear wheel drive American cars.

You would think if it matters when a fan is in the engine bay with all that other noise if would matter enough if its on your table top blowing directly at your ears.

 

Yep, water pump mounted, automotive cooling fans are asymmetrical to help with noise. And yes, I've never seen an electric motor mounted automotive cooling fan that wasn't symmetrical, but this may simply be a manufacturing thing.

 

As Petros mentioned earlier, smoothing the blades can be helpful. Folks with wind generators also have a desire to quiet the blades of their 'fans'. Here is a brief discussion where some success was had by sanding the rough casting edges of the blades with 400 or 600 grit sandpaper, and then waxing or varnishing them.

http://janice142.com/BoatInfo/QuietWind.htm

 

SamSam, in fact this seemingly trivial problem has quite a lot to do with flow phenomena studied for sails, hulls and propulsors. So, Squiddly-D; do some Googling on "owl silent flight".

The major noise source is the trailing edge; you might try to mimick an owl wings soft, serrated trailing edge by adding a strip of tape or textile with V-serrations, say about ten millimeters "free overhang".

The owl wing also has a velvet-like surface on the aft part of the sucion surface, that has a smoothing action. I've seen lab tests with fibers glued to a pipe inner wall and acting as damper on the turbulent flow. It is even possible to change a turbulent flow into a laminar at the trailing edge.

Y'a know, a sailors beard may reduce his wind resistance by going laminar..... and that goes for the face in the fan flow as well.......