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Forum Index : Windmills : Intro from newbie and controller question
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moose4621 Newbie  Joined: 10/01/2012 Location: AustraliaPosts: 30 |
I am listening Glenn. Thanks for your input. I knocked up an anemometer this morning. It's body is machined from PVC bar stock, the arms from 3mm S/S and the cups pressed from 1mm aluminium sheet. Overall dia is around 300mm. 
The arms are drilled and tapped at 10 deg to aid in clearance. 
There are two 10 x 2mm neo's in the bottom of the rotor with recesses for two more if required. The base has been drilled to accomodate a hall effect device or reed switch. 
The cups were pressed using a punch and die I had already made for another project. It spins up at the drop of a hat and seems to do it's thing so now I need to work on the electrickery.  A cordless sensor would be nice.  He who dies with the most toys, wins! |
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yahoo2 Guru  Joined: 05/04/2011 Location: AustraliaPosts: 1166 |
Jeez moose, that is a BL  DY steep hill, my knees are hurting just looking at it!
the anemometer looks the business though. 
yahoo I'm confused, no wait... maybe I'm not... |
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| moose4621 Newbie Joined: 10/01/2012 Location: AustraliaPosts: 30 |
Oops! 
Should read relatively fine pitch and extreme positive angle of attack near the root. He who dies with the most toys, wins! |
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| yahoo2 Guru Joined: 05/04/2011 Location: AustraliaPosts: 1166 |
My personal opinion is that the inside 60 -70% of a blade does not contribute much, if any power to a small turbine. The perfect blade will generate good power low down in the rev range with the majority of power generated near the tip. Then as it gets closer to its rated speed the blade will progressively stall from the tip inwards keeping the speed down to an acceptable level. There is no need to be trying to extract extra power beyond the revs where the mill starts to furl. The straight cut GEO-222 ticks all these boxes. The one downside is that once the mill is fully furled the blades can come out of stall and generate some freaky lift as the blade is traveling on the "downwind" leg of its circle (its caused by the air vectoring at a diagonal towards the blade tip) and the power output will continue to climb with the wind speed. I'm confused, no wait... maybe I'm not... |
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| moose4621 Newbie Joined: 10/01/2012 Location: AustraliaPosts: 30 |
Ummmm, welllll, actually, the extruded blade, (zero twist), stalls at the root first! He who dies with the most toys, wins! |
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Tinker Guru Joined: 07/11/2007 Location: AustraliaPosts: 1904 |
Moose, forget the reed switch idea for your anemometer. There things are rated for perhaps a million cycles which is reached in relatively short time period if there's wind about. I tried it and the switch failed not long after mounting the thing on the TV antenna mast. Hall switches are good but you will not get good steady low wind speed readings with just 2 or 4 magnets. I use an opto sensor & slotted disk, I think there were 10 slots in the disk. Your alu caps look mighty fine, I hope they do not corrode away where in contact with the ss rods. I used black plastic cups and they have been running for over 20 years by now. The biggest hassle by far is how to get the low friction ball bearings stay low friction and at the same time keeping the rain water out. I can see your design fail in that area - sorry. Been there, done that. What worked for me is to mount the thing upside down so one can have a fixed sealed hood over the rotating part. If you look at the way anemometers on yacht mastheads are constructed you will find they too use that method -and they work in a very harsh environment. Klaus |
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| yahoo2 Guru Joined: 05/04/2011 Location: AustraliaPosts: 1166 |
OK stall is not the correct term. I have bailed up so called experts on this a number of times. The best they come up with is reduced lift and increased drag due to wake turbulence and other aerodynamic phenomena that are not symmetrical with the axis of rotation.  When I press them on exactly where the testing was done, that their numbers are based on, they mumble about contracts or commercial in confidence agreements and usually call security.
It doesn't help much. 
Most research into auto-rotating blades died with the gyro-copter when it was replaced with the helicopter. Most small wind turbine theory is "modeled" on assumptions that date back to the 50's and 60's. Most successful blade shapes are evolved from hobbyists experimenting (like yourself). Fillm is right, the more aerodynamic theory you apply to a rotor, less than about 8 foot the worse it seems to fly. I have only seen three rotors with a twisted geo222 profile, they were all pitch controlled machines, the blades had been modified from something else and the turbines were beyond repair, so I never got to see them fly. yahoo I'm confused, no wait... maybe I'm not... |
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Madness Guru Joined: 08/10/2011 Location: AustraliaPosts: 2498 |
Surely the people who make those giant turbines have done a lot of research into blade and aerofoil design? There are only 10 types of people in the world: those who understand binary, and those who don't. |
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| moose4621 Newbie Joined: 10/01/2012 Location: AustraliaPosts: 30 |
Yeah, I was thinking the same thing but I did read somewhere that someone was using a reed as a tacho sensor! Seems to work on push bike speedo's with just one magnet. 20 Years? holy smoke. I wasn't thinking that far ahead. Seriously though, thanks for the advise, I appreciate it. He who dies with the most toys, wins! |
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| moose4621 Newbie Joined: 10/01/2012 Location: AustraliaPosts: 30 |
Aerodynamics is not rocket science and has been under constant review and refinement for centuries, including rotary wing. The science is well tested and proven and the results written in blood. I'm not sure what it is you don't have an understanding of, but I don't believe it's a new phenomena that has never been seen before. The only real difference between large and small turbines from an aerodynamic stand point is the Reynolds factor. Again well researched, understood, and documented and easily corrected. The only hard part from my standpoint, (and most others apparently) is matching the aerodynamics to the load and conditions. If nobody can recall a set of blades carved correctly with the GEO222 airfoil, then that tells me there is a large gap in the R&D that needs investigating. He who dies with the most toys, wins! |
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Rastus Guru Joined: 29/10/2010 Location: AustraliaPosts: 301 |
Hi Moose 4621, I'm keenly interested in the Geo222 discussion you'v raised and would benefit from it's developement.I'm not well informed about aerodynamics,but have had similar ideas to what you are discussing.Carving a larger aproach angle closer to the hub and including an over sized nose cone with a slow helix included to assist lower wind start up.How this would impact on effective furl is questionable.Would you be able to exspand on these comments at all?Cheers Rastus see Rastus graduate advise generously |
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| moose4621 Newbie Joined: 10/01/2012 Location: AustraliaPosts: 30 |
Hi Rastus. I think Yahoo pointed out earlier that the outer part of the blade does most of the work but of course, that doesn't mean that the root section has nothing to offer. Every little bit helps and some sort of course helix on the spinner would offer some assistance to the start up torque required get get the thing moving but whether that assistance is significant or not depends on a lot of variables. I'm not going to make any predictions to the effect it has on the furling as I have virtually no experience with furling and no idea what your rotor disk looks like but I would simply say the if you increase or decrease the total drag on the rotor disk it will effect the furling. Not much help I know but without details, it's a bit like asking how long is a piece of string.
I'd like to point out that while I have some professional and personal experience in aerodynamics, I have none in wind generators so don't give me too much credit. He who dies with the most toys, wins! |
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| moose4621 Newbie Joined: 10/01/2012 Location: AustraliaPosts: 30 |
Hi Gizmo, lowered the mast today to fit a 80 series alternator. Both the 60 that was on it and the new 80 are both wired 2x7c. Zero wind since it went back up. 
I also reduced the tail area by around 30% in an effort to stop it hunting so much. I scored 5 F&P motors locally for nix and includes 60s & 80s, no 100s though. I may be keen to try a dual but I'm not so keen to run the dc all the way from the mill to the shed, over 80 metres away. That would definitely mean heavier cable. Once I convince myself that the site can produce enough wind, then no problem, but until then. So, given my lack of electronic prowess, I am looking forward to suggestions to improve the output of this new alternator. He who dies with the most toys, wins! |
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| yahoo2 Guru Joined: 05/04/2011 Location: AustraliaPosts: 1166 |
Finally caught up on some sleep. Been out fighting bushfires most of this week, not a lot of fun! I trudged out in the paddock and had a close look at my anemometer, I have a little trouble with the bearing on the wind direction indicator this only has a 45 degree skirt to keep the water and the dust out(and its on the top). The anemometer hanging underneath has a double skirt. A straight inner skirt hangs down past the hub top surface about 3mm with a 1.5 - 2mm gap at the sides. the 45 degree outer skirt ends level with the inner skirt with about a 7 mm gap at the bottom edge. the only other trouble I have is parrots chewing the wires and radiation sensors.  Having some cable ties bristling out around the wires has stopped them.
yahoo I'm confused, no wait... maybe I'm not... |
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| moose4621 Newbie Joined: 10/01/2012 Location: AustraliaPosts: 30 |
Geeze, I thought everywhere is wet by now. Obviously not! I assume people have tried using little neo's as low friction bearings. I haven't seen any threads along those lines though. I guess there is a problem with them? I nearly machined one up yesterday just to see how it would work but got sidetracked doing something productive instead.
Bunnings is selling plastic hawks and owls at the moment. We put one on our vegie garden and got rid of the parrots. (for now). He who dies with the most toys, wins! |
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| moose4621 Newbie Joined: 10/01/2012 Location: AustraliaPosts: 30 |
We have had some wind the couple of days and with the new 80s stator I am still disappointed. The best max so far is 4.0a @ 52.4v. I was expecting more. I have been reading through the f&p and capacitor threads on here which has taken a long long time. I'm still no closer to choosing what capacitors to install as per gordon's circuit. It seems like it's a unpredictable science. But surely someone has experience with an 80s stator in 2x7p on 48v batteries that can give me a starting point. I read with great excitement that Bryan1 scored a 250% increase in peak output with his setup but that's with a 100s stator. It would be handy if there was a table showing various setups and results as per Oztules suggestion. Any ideas? He who dies with the most toys, wins! |
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Gizmo Admin Group  Joined: 05/06/2004 Location: AustraliaPosts: 5078 |
Hi Moose 204 watts is better than 175 watts, so you've gained something at least. But all this is irrelevant without knowing the wind speed. It may be the wind turbine is performing well, but you dont have enough wind speed to see much over 200 watts. I agree a chart comparing the different stators and outputs would be handy. Its been on my to-do list for some time, but I've either not had the test gear or the power source set up to do the testing. Yes it is a bit of a unpredictable science, lots of unknowns. A slight change in turbine blade angle can have a big effect on performance. And you can have one windmill that makes 200 watts max but will give more watt hours than a windmill that makes 400 watts max, its more about the low speed performance that max power. Glenn The best time to plant a tree was twenty years ago, the second best time is right now. JAQ |
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| moose4621 Newbie Joined: 10/01/2012 Location: AustraliaPosts: 30 |
Thanks for the reply Glenn. The anemometer wizardry is a little way off yet. I need to make a decision on which logger and then order the parts. From a subjective position, we have been getting really strong gusts and the turbine has been getting around 500 - 600 rpm, (estimated), in the furled position. My multimeter is giving really weird readings on Hz so I'm guessing there's a problem with the meter or the wave form from the gennie is distorted. But, I think the technical term is, "going like the clappers". 
The gennie is not stalling the turbine by any stretch so I am assuming there is plenty more power to be had from the turbine. The 80 stator has a higher cut in than the 60 but produces more power at low rpm than the 60. I am sure it will produce many times the A/hr's of the 60 but there must be more available. I should add that the stator is in star config. He who dies with the most toys, wins! |
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| moose4621 Newbie Joined: 10/01/2012 Location: AustraliaPosts: 30 |
I've found a couple of round tuit's today so I started on the next mill. At this stage I am planning on a 60/80 dual with the 60 in delta and voltage doubler caps and the 80 in star with series and doubler caps, maybe. (Subject to change without notice). Has anyone rewound one of these stators with heavier wire? Anyway, plenty of time to think about that later. Hardware first. The bearing housing is 75 x 75 x 4 RHS with 75 x 16 flat bar at each end machined for 6005 bearing which protrudes the steel end plate and locates the stator as per washing machine. The corners of the 75 x 16 flat bar have been machined to allow the stator to fit. 
The shaft is simply a modified original from the washing machine with the bearing step removed and the spline on the agitator end extended to allow the second rotor to mate with it's stator and still have the original spline for the prop adapter. 
I've got to get the bearings before I go too much further as the next step is testing in the lathe for various configurations. (Why didn't I grab the bearings out of the washing machine? Good question)! He who dies with the most toys, wins! |
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