Turbine Construction Progress

[Boondocker]

Hello,

Attached are progress photos of my second wind turbine project under construction.   This turbine was inspired by the design posted by Chris Olson, 48dc MPPT.

http://www.fieldlines.com/index.php/topic,147278.0.html

http://dairylandwindpower.us/projects/Direct-Drive_3.2meter_MPPT/index.html

I built in some flexibility so adjustment can be made.  Some modifications are:
•   Magnet rotors are 14” instead of 13”, provide more room for possible stator winding changes.
•   The offset for the turbine shaft center line is adjustable, so it can be reposition with a change in blade length.
•    The prop hub, has jacking bolts behind support arms to better align the blade tracking.









The coils are made out of 65 turns of 14g wire



Coils are place in a jig to position them for soldiering and attaching them to one another.

[Boondocker]

When making the stator mold, there is a relief pocket to provide extra space for the coil return wire.  This will prevent this wire getting hard press against the top portion of the coil .  Also, having this pocket in the mold allows the active area where the magnets over the stator to be thinner by a wire width.

[Boondocker]

Hub
The prop hub design also originates from a Chris Olson project.

 http://www.fieldlines.com/index.php/topic,144577.54.html?PHPSESSID=bd86d441f62e40ca9df585aa8d6bf1a8


Machining the hub plate surface with resources available was found to be difficult.  Encounter much chatter due to plate flexing while surfacing.  A work around was to stiffen the plate by welding gussets to the back.

My machining lesson rigidity is paramount.

Just in case the 0.010” runout affects blade tracking, added fine thread jacking nuts and bolts behind the support arms for fine tuning if necessary.  There is also a kerf cut in the angle iron support arms to provide a deflection point.

[Boondocker]

Alternator Testing

An air gap of 0.700” provides a comfortable magnets and stator clearance.   I tried a 0.600” gap and  the stator position just so right to avoid and contact.   

Testing the alternator obtained  2.14dcv/rpm at 0.700” gap, and 2.32dcv/rpm at a 0.800” gap  between magnets.

[gww]

Don't stop now, want to see more. How much will it wheigh?  I'm having fun and thanks
gww

[Boondocker]

I haven't put it on scale.  But when I do weigh the turbine, I'll sum up the parts.  It is not light weight!

[hiker]

nice work.......................

[kitestrings]

Bd,

Nice work and great pics.  Update when you can.

I'm a little confused by the testing results.  Wouldn't the higher voltage be obtained witha closer air-gap?  The chart appears to show this, but not the numbers prior.

What is the mesh that you are using?

Keep up the terrific work.  ~ks

[tecker]

Some nice mods on the stator mold the inset for the coils is interesting .

[Boondocker]

Kitstring,

Been away for awhile.   The mess used when molding the stator was 6oz E-glass.   
Good eye, yes I swapped the voltage valves.

[Boondocker]

 I completed most of the work on the tail vane.     It is constructed with ¼” bead&cove  cedar strips glued together and then covered with a layer of fiberglass/resin.  The wood was leftovers from a previous project.  This method makes for a very strong and light tail vane.  It is going to be a shame to paint.

I've also glued up spruce lumber for the blades.   Will be carving wood soon!

[kitestrings]

I wonder if you could seal with lynseed oil as others have done with blades, instead of the paint.  I like it; and the kayak too.  ~ks

[Boondocker]

KS

Going to need UV protection for the durability of the fiberglass.  So paint is the best option.

The tail vane detail will not too noticable when 90ft above the ground.

[upstateman]

Alternator Testing

An air gap of 0.700” provides a comfortable magnets and stator clearance.   I tried a 0.600” gap and  the stator position just so right to avoid and contact.   

Testing the alternator obtained  2.14dcv/rpm at 0.700” gap, and 2.32dcv/rpm at a 0.800” gap  between magnets.

(Attachment Link)

(Attachment Link)

How did you spin the alt to get your readings?Were the rpms set at a speed to simulate a certain wind speed?I am digging the project.

[Boondocker]

Upstatsman,

I spun the hub by hand, with no load it will spin freely.   The photo with the oscilloscope, shows the 1/4" key stock extended past the shaft. I used it as a hand crank. 

Crank the turbine at different speeds, read the rectified dvc volts off the multi meter, and the hertz from the oscilloscope to get the rpm.

In the past, I've performed more elaborate load testing on the alternators attached to a VFD drive to control the speed.
http://www.fieldlines.com/index.php/topic,128955.msg834202.html#msg834202

[upstateman]

Upstatsman,

I spun the hub by hand, with no load it will spin freely.   The photo with the oscilloscope, shows the 1/4" key stock extended past the shaft. I used it as a hand crank. 

Crank the turbine at different speeds, read the rectified dvc volts off the multi meter, and the hertz from the oscilloscope to get the rpm.

In the past, I've performed more elaborate load testing on the alternators attached to a VFD drive to control the speed.
http://www.fieldlines.com/index.php/topic,128955.msg834202.html#msg834202

I got it.More simple than I thought.

[Boondocker]

Blade progress:

[upstateman]

Please forgive all my Q & A,still learning. Are the tips left on for balancing?I may be getting ahead of you.If so,sorry bout that.

[Boondocker]

Upstatesman,

I haven't removed the ends yet.   The ends of the blade blanks also have registration pins that are useful to check blade spacing.

I was very pleased the greatest distance different between the pins was just shy of 1/8” without adjustment.
 

[upstateman]

Upstatesman,

I haven't removed the ends yet.   The ends of the blade blanks also have registration pins that are useful to check blade spacing.

I was very pleased the greatest distance different between the pins was just shy of 1/8” without adjustment.
 

I see.That's pretty close.

BTW,is it considered DIY cheating when you use CNC equipment? 

[Boondocker]

The CNC router is DIY. 

http://www.fieldlines.com/index.php/topic,147331.0.html

[upstateman]

The CNC router is DIY. 

http://www.fieldlines.com/index.php/topic,147331.0.html

That's so cool.Next up is a DIY 3D printer.

[dnix71]

About blade balancing, you said you intend to fiberglass them. After the first coat you could weigh each and also do a center of mass check by balancing each blade on a rounded nail head.. If each blade weighs the same and has the same center of mass measured from one hub hole, then they are static balanced. The second fiberglass coat would be used for correction and the third coat to get it as close as you can.

Spin balancing is probably beyond doing. Spin balancing would tell you if the profile of each blade is the same. If you have an old metal fan and twist one blade more than the others it makes the fan wobble. If the rpm is low enough static balancing is enough.

[Boondocker]

Dnix71

Thanks for the balancing information.  For now, I'll keep the fiberglass limited to the tail vane.

My plan is to paint the blades with sliver color POR15, instead.

[kitestrings]

Boondocker,

The blades look great, and a nice carving set-up as well.  I also recall your earlier project with the rather high-tech test set-up, but I hadn't connected it to you.  Is the first turbine still up and working?

Oh, and a question...I think you settled on a gap of ~.700-.800", but how thick is the stator?  I was just curious what you're mechanical clearance ended up.

Regarding Upsatesman's question on measuring speed - an oscilloscope is probably a nice tool if you have one, but not at all necessary to estimate alternator speed.  It can be measured with an inexpensive handheld rpm gage, or calculated from frequency measurements:

rpm = freq (hz) x 60 / (# poles/2)

best, ~ks

[upstateman]

Boondocker,

The blades look great, and a nice carving set-up as well.  I also recall your earlier project with the rather high-tech test set-up, but I hadn't connected it to you.  Is the first turbine still up and working?

Oh, and a question...I think you settled on a gap of ~.700-.800", but how thick is the stator?  I was just curious what you're mechanical clearance ended up.

Regarding Upsatesman's question on measuring speed - an oscilloscope is probably a nice tool if you have one, but not at all necessary to estimate alternator speed.  It can be measured with an inexpensive handheld rpm gage, or calculated from frequency measurements:

rpm = freq (hz) x 60 / (# poles/2)

best, ~ks

Thanks.I have,or had, an optical tach that only needs a reflective dot to read rpm.Harbor Freight sells them,or used to.

[Boondocker]

Kitestring

Yes, my first turbine is still in service.  It has survived five years of operations.

http://www.fieldlines.com/index.php/topic,147243.msg1015599.html#msg1015599

 
On the new turbine, the portion of the stator that is near the magnets is 0.51”.  So the magnet to stator clearance is around 0.15” with the 0.8” gap. 

[Boondocker]

More blade photos

[Boondocker]

Adjustable off-set

[Boondocker]

Painted Parts

[Boondocker]

Indoor assembly

[upstateman]

I have an aviation back ground and we use prop cones to smooth out the airflow over the hub and blade base.Do you think that may help with a turbine the size you're building?I know it helps the big boys.

[birdhouse]

AWESOME looking build!  i'll bet ya can't wait to get some amps from that thing!

as per nose cones, i believe this has been gone over a few times.  as i understand things, the root of the blade is only really needed to start prop rotation in low winds.  once the machine has gotten up to power producing rpm, the root is actually pushing wind, not being pushed by the wind, so a nose cone is of little use. 

some here think the inner third of the blade is almost useless, so smoothing the air coming off the center of the prop would create better flow to a useless portion of the prop???   

adam