Wind Turbine Testing Follow up

[Matt Au]

Hi Adrian and others,

I can give you some photo`s of various stages of the construction of my new Turbine and some details on the sequence of event`s.

I did not want to mention earlier that i use PVC pipe blades, as i would imagine many people would think it stupid to state these high output figures when using these blades.

Before i go on, i have been shaping these blades now for 4 years and have got a good air foil shape worked out, mainly with trial and error and had no problems with fatigue.

Another point i would like to mention is that I have noticed a distinct increase in efficiency/output when i mount the blades on any of my turbines, so that the leading edge is aimed at the centre shaft and the trailing edge away.

I have noticed other people mounting these blades the opposite way, and in most cases i have noticed that general blade/hub design`s are arranged so that the blade is mounted with it aiming to the centre shaft.

Construction: I started with a 40Amp 24V truck alt, I expected with strong magnets, that it would reach 15V at a good cut in speed.

I then machine the standard field coil rotor down, in a way that the fingers are machined off and you are left with two 80mm/10mm steel discs.

Then i make up 12 flat steel plates from a length of 20mm/4mm steel, cut into 50mm long length`s which i then clamp down onto the discs with a large hose clamp and weld in place.

You then arraldite the magnets in place before resining with a strap in place so they don`t go flying.

Important: You must arrange the 12 steel pieces and Magnets so that there is a bigger gap between two, this reduces cogging a lot, also the magnets must be arranged so that they are angled slightly, this also reduces cogging.

All this helps when making a blade for high speed performance.

The magnets are about 1.5mm from stator.

Blades: I use three blades, the root is 95mm wide, the tip is 40mm wide, the thickest part of the blade is 7mm, tapering of to the trailing edge at around .5mm.

The pitch at the root is about 18 degrees, half-way point is 9 and the tip is about 4 degrees.

I sandwich the blades between two triangle cut pieces of 4mm alum plate.

Finally, I think another boost to the efficiency, is the use of thick Neo rare Earth Magnets, i use 25mm/30mm/11.5mm Neo mag`s.

I am very excited about this new turbine and want to get it tested properly to get an honest output figure, so far it looks very good compared to my Dual motor 2.2M F&P Turbine which is only just ahead in performance, and other car alt conversions i have done and had to rewire the stator have put out 10Amps/140Watt at 10m/s with a 1.2M blade rotor.

This one is putting out around 28Amps/380Watts at 10m/s with a 1.5M blade rotor.

And not bad at lower winds eg: 10amps at 6m/s, and a cut in speed of about 3-4m/s.

I will be setting up a Web site soon detailing many projects, My F&P turbine pics and an article on it can be found at www.thebackshed.com and Thank`s to Glenn at thebackshed for publishng the info.

Matt Au.

[drdongle]

Looks really great, vary ingenious design, However you could further increase the out put by replacing the steal shaft with one that is stainless, or bronze. The stock steel shaft acts as a magnetic short circuit that reduces the number of flux line available to cross the stator. Id like to see some more close ups of your hub and blades. keep up the good work!!

[georgeodjungle]

pvc blades ROCK!abs not as good.

i see the mast on the wall.could be a song in that.

how about a side shot of the hub?

looks like you could adjust the pitch?

[Flux]

If I understand correctly, the shaft will make no difference, he seems to be making a drum with the steel strips and adding the magnets on top, it is no longer a claw rotor, just more like the usual motor conversions.

Flux

[hvirtane]

Very nice.

Thank you a lot for sharing

this project.

I like the simplicity of

the turbine, the blades

and the alt.  

The output is really good.

Can you give more construction

details about the blades?

- Hannu

[WBW40]

very nice

like you i have also used pvc blades made from guttering

for to years with good power at low wind with 6 blades

one meter diamiter,i can cut out these pvc blades in

45 mints and only cost me £5.00 for the guttering 6 ft

lenth, my geny is a 10" single rotor 12 mags 9 coils no lams,

60 rpm cut in ,18 ft pole 8 to 10 amps in 10 to 15 mpa wind,

i also have 160 watts of solar .so the little wind mill dose

well .

having fun with pvc

     ceep up the good work

[Matt Au]

Hi All,

Thank you all for the nice comments on my turbine.

Will post some more photo`s soon and a bit more info, have to go for now.

Matt Au.

[Matt Au]

Hi All,

Re: WDW40 Query, I have also built similiar sized 1.2M Turbines, and have found in most cases, even in lighter wind conditions it is better to use three or less blades.

When testing 6,4,3, and even a 1 bladed rotor all being 1.2M rotor diameter, I found a distinct power increase when using 3 blades compared to 6.

Also when using one blade with a counter weight, I got nearly the same performance as the 3 blades, but the Turbine & Tower tended to shudder a LOT when it yawed to find the wind.

6. blades I got 90Watts@10m/s.
   
3. blades I got 140Watts@10m/s.
   
1. blade  I got 120Watts@10m/s.
   
   

All these test`s were done with a PM bosch 40 amp car alt, which I rewired the stator with (.8mm wire with 18 turns per coil) and configured with more coil area and then converted to a rare earth permanent magnet type using Neo 12mm/20mm/6mm magnets, in the same way i did the truck alt conversion.

From now on i will be using 24 truck alt stators as they have heavy gauge wire and enough windings to reach say 15volts at a good cut in speed of around 300-350 rpm which suits the small rotor swept area being 1.5M. They are also rated at 30-40Amps in standard form.

Another point I would like to make is the use of, AS STRONG magnets as you can afford or fit into an area. This can be hard as rare earth magnets can be very costly. I have been lucky enough to find a good surplus supplier of odd sized Neo magnets cheap.

Attached is a rough side on shot of the Truck alt turbine on work stand, in the distance are F&P washing motors 3phase 56pole, 42 coil Permanet magnet motors with a 400mm/25mm stainless shaft (Great for Wind turbines).

Also a pic of my 2.2M Dual motor F&P Turbine, and one of the 24V Truck alt stators.

Will get some better pictures together soon.

Matt Au.

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[drdongle]

Ya know what I believe you are right, now that I have thought about it for a few minutes, it's a light weight equivalent of a machined down induction rotor.

[hvirtane]

Hi,

the pictures, which you uploaded first

seem to have been disappeared

from the server.

I'm very impressed with

the simple construction

of this machine and

its performance.

I wanted to see more pictures

about the blades and the generator.

Also I wanted to know, which kind

of furling system, if any,

you are using.

- Hannu