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Forum Index : Windmills : Lenz Turbine I’ve got the bug
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Bryan1 Guru  Joined: 22/02/2006 Location: AustraliaPosts: 1343 |
Hiya Glenn, Well mate I've been thinking of what would be the best way to utilize that 300mm pvc pipe I got from work for nothing. Time for me to make up a Lenz turbine I reckon  . Now going off Ed's formula on his website going with a 300mm wing width the diameter of the mill will be 2.143 metres with a chord width of 606mm. Now I may ask yours looks like a similar size so what height did you make the blades? I'm thinking for mine going 2.5 metres high and as far as the structural supports I'm going to draw up the profile in autocad and try my own design. As I get some decent strong winds here on the farm I'm going to make a heavy duty tapered bearing arrangement for the central shaft and I have a spare F&P motor here to throw on it as my other F&P motor is going on my 8 ft blades and hopefully up in the air by the weekend after next. Anyway mate hopefully I can throw in some good info and I'll take photo's where I can.
Cheers Bryan  |
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| thefinis Regular Member  Joined: 23/08/2006 Location: United StatesPosts: 53 |
Bryan I think that you are using the old figures that he has posted. They will work but not as well as his new version. As Glenn has been reluctant to post details of Ed's lastest work both out of respect for Ed and the fact that it is an on going project that gets updated often I will follow his lead. Do a search for the Lenz 2.4 or write Ed. I am looking at making a big one with modified numbers(not much) to match existing materials. These babies are material intensive lots of surface area and slow moving due to a tsr of .8 or less. From what I have seen and heard you are better off to go with too big a wing for the diameter than too small. Finis Texas born and bred |
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| thefinis Regular Member Joined: 23/08/2006 Location: United StatesPosts: 53 |
Sorry Mate I gave a quick reply this morning because I had to go fix fences knocked down from flooding. Here is what I should have posted. The numbers I come up with for a wing width of 300mm are a diameter of 1600mm and a chord of 640mm. Based on his lastest figures. I am sure Windstuffnow Ed would love it if you could post pictures and details of one of his babies after you have built it. Finis Texas born and bred |
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Gizmo Admin Group  Joined: 05/06/2004 Location: AustraliaPosts: 5078 |
This is the link to Ed's diary on Other Power. http://www.fieldlines.com/story/2006/4/28/24156/8677 But I think Ed has made a few improvements since then. Bryan do you have a cad program, I can send a DXF of my little Lenz2 ( 1200*1300 ) that you could scale up to suit your 300mm pipe. Glenn The best time to plant a tree was twenty years ago, the second best time is right now. JAQ |
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| RossW Guru Joined: 25/02/2006 Location: AustraliaPosts: 495 |
Funny, I found (and was looking at) exactly that page about 7:30 this morning Glenn! I was showing Kathy (my better half) and musing about pulling down the top half of my old 45 foot tower from the old pace and bringing it up here. While looking at that section, Kathy (both of is flyers from way back) was saying the wing section looked "very thick". I explained that with a TSR of 0.8, the "wing" is actually a "scoop", trying to catch as much wind as it can while facing downwind, and letting it past while facing upwind. That in turn led me to thinking about a possible alternate system for a VAWT. It'd require some fiddling about to get it "just right", but imagine a blade with a pivot and stops. When the wind is "behind" it, it would extend out (ie, pivot and "blow out") to catch the greatest amount of wind. Once it gets to the furthest point of travel (in fact, the point at which its own tangential velocity was greater than the relative wind at that point), the blade would fold back "out of play" thus reducing drag on the upwind return. Getting the turning moment right so that the whole thing remains balanced could take some ingenuity, but an extension to the blade with a fixed weight could work to keep the centre of mass (and thus, the balance) constant. I know the idea to date has been to keep the thing to a simple, no-moving-parts design, but surely maximising the power out is the real aim of the game? Has someone already been down this road? |
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Megawatt Man Senior Member  Joined: 03/05/2006 Location: AustraliaPosts: 119 |
Hey Gizmo, there's a bit of blue skying happening here, so I may as well make a contribution. In my perception, one problem requiring compromise with the VAWT is that the blade has to oppose the wind direction as it returns to the power producing half turn. What if the rotor ran around a stationary central gear that meshed with three planetary gears, each at 120 degrees. (for a three bladed assembly). Each blade would pivot on a shaft that was linked to a crank connected to an eccentrically located bearing in the planetary gears, so that the blade is turned edge on to the wind during its return half turn. This principle was used in auto clothes washing machines in days that I can remember, to cause the agitation action. Problems I can see are cost and complication, while it would be to no purpose if the energy to rotate the blades exceeds the loss due to turning against the wind. Although I like thinking about the eccentric crank system, I reckon that a better answer lies in the experiments involving an incoming wind guide that at once forms a venturi in which the VAWT operates and shields the returning blade. The proponents of these systems claim a TSR exceeding unity too. We'll see! Megawatt Man |
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| Gizmo Admin Group Joined: 05/06/2004 Location: AustraliaPosts: 5078 |
I built a VAWT with wings that changed direction as it rotated. Again, based on work by Ed. It had a tail to keep it facing the wind, as it were, and it worked fine. But it had a hell of a lot of moving parts, and needed oiling every couple of weeks. It eventually fell apart. A vertical that changes wing angles, needs to follow the wind, like a HAWT. And thats what I'm trying to get away from. The BIG advantage of a true VAWT is its ability to use sudden wind direction changes, turbulent winds. A gust from any direction will be used, it doesn't need to "find" the wind before it can make power. Designs like the Darrius and Robatec use lift to drive the blades. The Savious uses drag. The Lenz is a combination, uses drag on the down wind side and lift as it goes around the back and front. Thats how it gets its extra power over a drag based machine. Ed, where are you???? I need someone who can describe it better than I. Glenn The best time to plant a tree was twenty years ago, the second best time is right now. JAQ |
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| Bryan1 Guru Joined: 22/02/2006 Location: AustraliaPosts: 1343 |
Hiya Glenn and Guy's, Firstly Glen I do have autocad 2006 on my laptop so I'd love the file I think you still have my e-mail address. Anyway it good to see since I started this post last night the amount of interest just in one day is great. I intend to do alot more research before I make this baby and as I paid for my 3kw sinewave inverter today the No.1 job is getting my 8 ft F&P in the air. I'll be using the 12 metre telescopic tower with another 3 metres of water pipe which I still have to get. Anyway the spot I've picked out for the lenz is on the top of the hill at my place where the wind seems to blow 24/7, this should get the baby spinning fast so strength in design and balance will be critical. So if things work out I'll end up making a few of them.
Cheers Bryan |
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| RossW Guru Joined: 25/02/2006 Location: AustraliaPosts: 495 |
Glenn, the system I was proposing would still work as you described. Basically, if the "blade" can move into an "engaged" position whenever the pressure behind it is greater than the pressure in front of it, it will "push" whenever the motive force is greater than the drag. Perhaps I should make a sketch. A picture is (they tell us) worth a thousand words! In my mind, I'm seeing a series (perhaps 3, perhaps more) flat blades, pivoted and with restraints (buffers, limits, stops, whatever you want to call them) so they will only open to parallel to a line from the axis (at most), and can only close to something near perpendicular to that, so they can "open" in the wind). I'm looking at cheap, efficient, simple and INDEPENDENT ways for each blade to move to maximise "push" and minimise "drag". |
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| Gizmo Admin Group Joined: 05/06/2004 Location: AustraliaPosts: 5078 |
This is the file I used when I put together my smaller Lenz windmill. Its a zipped up DXF file. 2006-08-30_205344_Lenz2fp.zip It was designed around some 250mm PVC pipe I had. I made the rest of the wing from sheets of 4mm ply wood. The steel ribs were laser cut from 2mm steel, the tabs bent over and the whole thing pop riveted together. There are also elongated bolt holes so I could make adjustments to the wing angle. Not shown are the winglets. I can see some gain in wings that move like you suggest Ross, but I do like to keep things simple, the less moving parts the better. I remember my little directional VAWT with the tail worked fine most of the time, but if the wind was turbulent, the tail would spin around like crazy to track the wind and all hell would break loose. One second the wings were facing the right way, the next they were working against the wind and the thing would shake itself to death. Glenn The best time to plant a tree was twenty years ago, the second best time is right now. JAQ |
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| Bryan1 Guru Joined: 22/02/2006 Location: AustraliaPosts: 1343 |
Hi Glenn, Thanks for that file mate I'm looking at it now and on scaling the drawing I'm getting a good idea for sizing. If I have some time tomorrow at work I'll start drawing my design up and I'll upload the file for everyones discrection. As I work with gearbox's I'm throwing away used bearings at a rate of knots so I can get a good free supply of bearings. On looking at Ed's link you gave before gave me a good insite to the newer version and I like the idea of a central bearing, I reckon atleast a 2" dia shaft should be used so the first thing I'll design is the bearing, shaft arrangment. One thing I was considering mainly for balancing and strength was using 2 rod's to hold each blade, each rod would have a left and right hand thread like a turnbuckle so I can adjust the camber just right which will aid in the balancing phase. Anyway mate I find autocad the best way to design stuff and it also cuts down on the stuffups so given time and coffee I'll hopefully get some drawings done. Cheers Bryan P.S. I noticed with the dxf file I couldn't get any pick points with the osnap so would you have the .dwg file. Anyway i'll postup .dwg files so all my layers and stuff should work with autocad. Thanks again mate Cheers |
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| Bryan1 Guru Joined: 22/02/2006 Location: AustraliaPosts: 1343 |
Hiya Guy's, Well I finally got some free time so I've designed up the drive arrangement for the Lenz This file is a dxg autocad file2006-08-31_221420_lenz_drive_design.rar and i've put in a few comments on the file to aid in veiwing it. I reckon it should be ok for the big lenz I want to make it just comes down to sourcing the material at the right price. Cheers Bryan Note: I tried to zip the file but when I tried the download the file was corrupt so I've rar'd the file and it seems to work properly |
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windstuffnow Newbie  Joined: 30/06/2006 Location: United StatesPosts: 31 |
Glenn is correct, it's a hybrid lift/drag machine and in order to get the maximum performance from it it needs to be loaded to a TSR of around 0.8 . It will run in the area of 1.6 to almost 2 unloaded but performance is poor. The drag machines, such as the savinous require a tsr of around 0.33 for best performance and true lift machines like the darrieus need a TSR of 4 or better to perform at their peak. Hopefully everyone found the files they needed to get the dimensions correct. If not here is a quick run down... dia x 0.4 = wing chord ( measured from the tip of the nose to the trailing edge ) and dia x .1875 is the diameter of the wings nose. The .4 maintains a solidity of about 38%. A few have made the chord length without including the nose and the turbines have suffered a bit at start up. If you make the wing chord to long it really messes up the wind going through the turbine. Bryan1, what is a "rar" designated file ? Tried to peek at it but it wouldn't open. I haven't transfered any of my drawing programs to this computer yet, what program is needed to view an rar? I've been away for the last few days with computer problems so I haven't been able to check the forums or get online for that matter. Hopefully things will ease up a bit and I can join in more often. I'll answer any questions I can... Have fun ! |
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| Gizmo Admin Group Joined: 05/06/2004 Location: AustraliaPosts: 5078 |
Rar is a type of compressed file, like Zip. There is a program called WinRar that can open them, but I've changed it to a zip file here 2006-09-01_070940_lenz_drive_design.zip. See how that goes. I was going to use a 50mm drive shaft and a pair of UC212 bearings and F212 cariers, similar to this, about $50 each set.  .
But taper bearings are a better option. The best time to plant a tree was twenty years ago, the second best time is right now. JAQ |
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Prof Newbie Joined: 01/12/2005 Location: AustraliaPosts: 33 |
Hi Guys, RE the central bearings - this is my $50 complete solution which has a 39mm shaft. An adapter plate holds the F&P rotor. I have a way to go yet building the Lenz H rotor (1.2 dia x 1.8 tall.) 
Considering what the original purpose of the bearing assembly was designed for I think it should be strong enough to handle a fairly big H type turbine such as ED has in mind. For a few dollars more even stronger hub assemblies are available. I will leave you guess what the bearing/hub assemble was originally intended for. Prof I know boats!! |
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| dwyer Guru Joined: 19/09/2005 Location: AustraliaPosts: 574 |
Hi Prof i had a look on your design is no big problem as it will hubs will hold nearly 1 tons and years ago l use to manufacture trailer for my customer and they all pretty good as my last trailer made was 2400x1200 tipper trailer has single 40mm axle and did carry 1.6 ton of sand without damage the bearing or blending the axle so l cant see anything wrong with your design
dwyer the bushman  |
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