Why Are My DIY Blades Noisy

[vawt]

I am trying to figure out how to avoid making noisy HAWT blades.

is the noise caused by the  trailing edge being to thick?
or is there another reasong, or even a combination of reasons.

Thanks for the help.
Regards
sam
farmenergyinc.ca

[just-doug]

pictures please

[SparWeb]

Usually, it's because they're turning too fast.  Find out what the tip speed is in miles per hour, km per hour, meters per second, whatever units you can tolerate.  Compare the result to mach speed.

Airfoil shape?  Blending at the tip?  Sharp trailing edge?  There could be a lot of other reasons - how can we guess with no information?

Wait a sec:  your question does not fit the context implied by the body of your posting.  Have you already built blades that turned out to be noisy (as the title implies)?  Or do you want to avoid making noisy blades in the future? 

[vawt]

I will take some picture and post them.
i have already built my blades and they are noisy.
dimensions:
lenght=42"
width at base=5.5" and .95" thick
width at tip = 2.25" and .375 thick
the trailing adge = .2" thick

they start making the "swoosh" sound at 100rpm
the last 6" of the tip is flat.
i will get pics soon.

thanks
sam

[Flux]

Why does VAWT want to make HAWT blades?

Certainly your trailing edge is very thick and that is the first thing to change. The other thing that makes blades noisy seems to be running faster than design tsr. At  only 100rpm you are most likely running unloaded. If you can get the load on above 100rpm and pull the tsr down it may be less noisy ( I hope you are not just testing unloaded blades)

If bringing the trailing edge to near a knife edge and keeping the tsr down doesn't do the trick then you will need to look at improving the tip shape, that can help.

Also try checking the blade tracking especially if the whistling is at rotational speed.

Flux

[Valalvax]

Why did no one suggest that they might be unbalanced? (or would they tear themselves apart if they weren't balanced?)

[vawt]

Thanks to all of you that is contributing in solving this small issue.
i think i will start by fixing the trialing edge and go from ther.
I am A VAWT man for sure (check out me Column-r vawt), however, i do feel that i need to dable the HAWT world a bit, besides it is still Wind Power.

thanks
 again
sam Chamas
farmenergyinc.ca