Re: [axialflux] Re: Coils
- Steve, Being non-magnetic, I didn't think aluminum would create any dragor cogging. mmmm. I'll take your word for it Steve. Thanks for the input!Loved Dan Lenox's turbine build write up! Great piece of work and shouldbe required reading by all !! "59 turns #14 2-in hand" Oh yeah!! Great stuff!!On Tue, May 31, 2011 at 6:50 PM, Steve Spence wrote:> And create large amounts of drag.>> On Tue, 31 May 2011 14:03:58 -0400, <daniel.bromley@...> wrote:>> >> > Dan, consider this for a moment if you will....> >> > * Make the stator plate with the likes of 1/4" 6061 aluminum plate....> > then, dipping the outer circumference in insulating resin... THEN> > winding the coils on it. ....Seems to me the plate would absorb> > unwanted> > heat rather well while offering great structural rigidity.> > Thoughts/input ?> >> > Dan Bromley> >> > On Tue, May 31, 2011 at 7:26 AM, Dan Fink wrote:> >> > We plan on a stator cast from vinyl ester resin with ATH filler to> > be> > able to dissipate about 3 watts per square inch of surface area over> > the coils, *in the wind.* (less when dyno testing).> >> > If your stator is getting so hot that complicated cooling systems or> > expensive epoxies are needed, you are wasting tremendous amounts of> > energy as heat, and should consider re-designing the alternator for a> > better match to the blades (more copper, lower resistance, more> > magnetic material)....or simply making the turbine furl earlier, as a> > quick stop-gap measure.> >>>> -->> Steve Spence> Renewable energy and self sufficiency> http://www.green-trust.org> http://arduinotronics.blogspot.com>>> ------------------------------------>> http://www.motherearthnews.com/subscribe/subscribe.aspx?promocode=EMEAD9Z4Yahoo! Groups Links>> <*> To visit your group on the web, go to:> http://groups.yahoo.com/group/axialflux/>> <*> Your email settings:> Individual Email | Traditional>> <*> To change settings online go to:> http://groups.yahoo.com/group/axialflux/join> (Yahoo! ID required)>> <*> To change settings via email:> email@example.com> firstname.lastname@example.org>> <*> To unsubscribe from this group, send an email to:> email@example.com>> <*> Your use of Yahoo! Groups is subject to:> http://docs.yahoo.com/info/terms/
- My answers are *starred* below.
co-author, "Homebrew Wind Power"
Buckville Energy Consulting
Buckville Publications LLC
NABCEP / IREC accredited Continuing Education Providers
Posted by: "James Morris" james-morris@...
Wed Jun 1, 2011 4:30 pm (PDT)
Aluminum will have zero effect on the magnetic lines
*That is correct
and if well insulated, will have zero effect on the electrical properties.
* Incorrect. The problem we are discussing is eddy current drag, and
there is no way to block a magnetic field.
I think Steve must have meant that a large aluminum plate would create
wind drag. That would have little effect on a vertical axis wind
turbine, but would be significant on a horizontal axis wind turbine.
* Not really -- the outer 1/3 of the blades towards the tips provides
most of the power in a wind turbine rotor. The inner part towards the
root where the alternator lives is insignificant for power production,
due to small swept area, slow speed, and mismatched angle of attack.
As Steve speaks of furling, he is probably thinking of a horizontal
axis. But axial flux generators are not really suitable for horizontal
axis wind turbines for that very reason. They have an unusually large
diameter. Standard generator configurations are more suitable for
horizontal axis wind turbines, but they are more difficult to build in
a home shop.
* See above. Alternator diameter is not an issue unless it is extreme,
and the use of strong magnets keeps the diameter relatively small. An
example of a commercial machine with a large alternator diameter would
be the Proven.