Project Journals > Chris Olson
3.2 meter ferrite magnet MPPT wind turbine
ChrisOlson:
On my previous geared turbines I placed the gearbox inline with the yaw shaft. With the heavy 3.8 meter rotor and lightweight neo generator they were balanced pretty nice on the yaw. However, once I retrofitted them with dual stator ferrite generators, the extra weight of the generator caused them to be slightly tail heavy. Those machines had a long input shaft housing that placed the rotor well forward of the yaw.
On this one, the rotor is lighter than the 3.8 meter. And the generator is heavier than a neo. So I attempted to move the weight forward as much as possible. I also wanted less offset (130 mm) with the smaller rotor. So I placed the gearbox ahead of the yaw and inclined the input shaft at 6° from horizontal
This one will not have an input shaft housing. This is the input assembly for it, and with the input shaft test installed in the gearbox
It looks like the rotor is a long ways out front. But this style rotor is for a downwinder. So the blades have a pretty radical sweep backwards at the root of the airfoil. There's not as much room there as it looks like there is. The blade roots clear the front of the gearcase by about 30 mm.
The tail hinge is welded on at 18° angle and 40° to the side of being straight back from a parallel line drawn thru the input shaft and yaw centerline. I also put a spring loaded damper on the tail return
After building and welding a stator mount to it, and building the tail boom, it's ready for assembly
--
Chris
Dave B.:
Hello Chris,
I got through the registration and the move successfully I guess. Great to see your latest videos on the turbine and I had to laugh at you being over ruled on the blade color. I like the look of those blades and will be anxious to hear of their performance with the new turbine. I know plenty are watching as well, let it fly ! Dave B
ChrisOlson:
I'm the most fortunate guy on earth because my wife takes an interest in all my wind power projects. And she comes out and helps with the turbines especially during installation, pulling the drop cable thru the tower, helping me lift and install an assembled rotor - she even wired a stator up on one once. So if she wants white blades on it, what the heck - white blades it will have.
Wait until she sees it run tomorrow when I finish getting the clipper built and installed. This one is a right hand turner - the rest are left hand. I can almost see it now - she'll be standing there with her hands on her hips looking up at it and go, "You put the blades on backwards."
And by gully she'll right once again - these blades are for a Talon downwinder ;D
--
Chris
rossw:
--- Quote from: ChrisOlson on January 13, 2012, 09:35:53 am ---I can almost see it now - she'll be standing there with her hands on her hips looking up at it and go, "You put the blades on backwards."
And by gully she'll right once again - these blades are for a Talon downwinder ;D
--- End quote ---
Silly question, don't laugh!
Is there any rationale at all for the conventional anticlockwise rotation?
I mean, ok, if one had nuts and threads that would work loose - fine. But many of the commercial ones I've seen have a keyed shaft, and with a locknut or castellated nut, they're not going to come loose anyway.
Or is it just convention? The first ones were made that way, and everyone makes them that way "because thats the way everyone else makes them"?
ChrisOlson:
--- Quote from: rossw on January 13, 2012, 02:18:22 pm ---Is there any rationale at all for the conventional anticlockwise rotation?
--- End quote ---
Yeah, it depends on which side of the equator you live on.
No - that was just a joke 8)
That's kind of an interesting question. All major horizontal axis turbines today rotate the same way (clockwise) because it's supposed to present a coherent and pleasing view. Early turbines rotated counter-clockwise like the old windmills, but the change to clockwise rotation happened after about 1978. One of the blade suppliers back then in Denmark made the decision to change direction in order to be distinguished from the Tvind (in Denmark) and their small wind turbines. Some of the blade customers were companies that later evolved into Vestas, Siemens, Enercon and Nordex. Since public demand required that all turbines rotate the same way, the success of the Big Four made clockwise the new standard.
The only other rationale is that it's "ideal" to have the blades turning the opposite direction of furling when looking at the machine from upwind. In other words, if you have a left hand furler, ideally you should have right hand (clockwise) rotating blades. And vice versa.
The reasoning behind that is to help prevent a tower strike during rapid furling. For instance, with a left hand furler, left hand turner, the bottom of the blade circle will flex towards the tower during a rapid yaw event to the furling side. Put right hand turners on that same machine and the bottom of the blade circle will tend to flex away from tower during rapid yaw to the furling side.
But still, which way the blades turn and which way it furls cannot "fix" an improperly designed machine that does not have enough forward "lead" of the rotor to the yaw axis. Nor "fix" a tip-to-tower clearance problem caused by not having enough inclination of the input shaft from horizontal. If you have adequate blade tip clearance to the tower, you won't have a problem with either one.
So basically the "standard" came to be because the human mind tends to prefer a right hand (clockwise) rotating machine, as it's supposed to be associated with symmetry somehow, or "the way things should be". But for somebody as screwed up as I am, even that doesn't make any difference :D
--
Chris
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