by steam_cannon » Fri 07 Mar 2008, 10:29:44
$this->bbcode_second_pass_quote('Tanada', 'F')rom counting the lead edge bumps in various pictures of different
applications I get 25-30 tubercle's per unti leangth. I don't know if
that is a hard an fast rule, or just how it worked for these but if I
can scrape up the resources (well I know I can't so why plan it?) I
would like to test it. What I would like to do is take two ceiling
fans which are identical, probably 4 blade models for economical
reasons, leave one factory standard and see what its power draw
is while running at each setting. Take the other fan and glue
thirty lag bolts on the edge of the blade so that the round end
hooks on the edge. Then test the modified fan to see what its
power draw is with the bolts in place. It would take more energy to
get up to speed because the bolts, even 1" size, are going to add a
lot of weight, but once up to speed inertia means the mass will stay
at speed and if the bolts make it more efficient it will make up the
energy needed to start.
Anyone willing to try out this test?
I'm not sure the power draw will be any different since if the design
works it will be moving more air at the same power. With a fan you
would have to measure wind speed from the fan. But you could also
put some long tissuepaper streamers on poles and take pictures of
the deflection. If one blade is moving 10% more air, it should be
measurable even by crude methods. And comparing two small
windturbines would be easy to test by measuring the power output.
Also I was thinking silicone or rubber would be a better material to
mold bumps. And with silicone being lighter, it would be harder to
upset the balance of the fan and easier to make corrections.
Here are a few easy methods a person could use for modeling:
* With just a tube of silicone... You might be able to do it by just
measuring and marking lines with a ruler. Then laying down a bead
of silicone and use a spatula to smooth it out. Whale flippers are
natural and don't need to be supremely accurate, so I figure as long
as it's smooth and you get the balance right it should give some results.
* Another way to test this would be to take small glue sticks from the
store and cut them in half (the hard part). Then cut down the ends
so when it wraps around the blade it is smooth. Then use a lighter
to stick it down.
* Also a glue gun could be used for laying down
bumps rather quickly.
* Another thing regarding silicone, molding with silicone is not too
difficult, with a little planning you could premold the add ons for
each blade so they would all be identical. For example, you could
use a long tray of "salt and sand" or thick plaster of Paris. Push the
fanblade edge (or a board or similar dimentions) into the tray about
1/4 of an inch depth and wiggle it so it's just a little wider. Poke in a
bump pattern with a pen or something. Dry your mold then spray
your mold with clear coat or lacquer paint so it soaks in. Then once
it's dry, yspray some cooking spray on your mold and clean out
extra with a paper towel or rag. Then put down a bead of silicon
and pull it out when it's dry. Then repeat and stick the molded
pieces onto your fan blades. One thing to remember though, unless
you are using a paper mold and a raised heat curing oven, your mold
needs to be less then 1/2 inch deep to dry in a reasonable time.
* Lay down measured strips of thick foam tape onto your fan blade in
premeasured locations. Then if you want that to be more
permanent, use rubber tool coating paint to make a smooth
permanent finish. It comes in several colors.
* Epoxy putty works pretty well with fan blades, I used it to repair
a metal fan blade a while back and adjust the blades balance.
"Wearing gloves", it could be mixed, cut and molded fairly quickly
and accurately. Then sand or use lacquer paint or rubber compound
for a smooth finish.
