Lenz turbine variation pics
By rotornuts, Section Wind Posted on Sat May 21, 2005 at 08:42:20 PM MST
It works but won't self start

Well the lenz turbine variation model is up and running in a very turbulent wind location and I'm happy about it. It's a crude model made from cardboard and cereal box wing skins with skate rolls as bearings so don't critique the asthetics. here it is doing about 180-200 rpm in an unknown wind that is very turbulent Here it is standing still. It stalls in the shadow position where the upwind blade is shadowing the downwind blade so it won't self start. If you give it a spin it takes off and spins nicely. Like I said before I think if I reduced the cord width in relation to the center it would run better and self start. Here's the origional post. http://www.fieldlines.com/story/2005/5/20/204046/109 Finally having fun, Mike

Lenz turbine variation pics | 17 comments (17 topical)

Re: Lenz turbine variation pics (3.00 / 0) (#1) by nanotech on Sat May 21, 2005 at 02:48:49 PM MST

Could you put something along the lines of the "windcatcher" from an anemometer to get it started? __________________________________________ My ship finally came in, but it was the Kobayashi Maru!

Re: Lenz turbine variation pics (3.00 / 0) (#2) by XRay on Sat May 21, 2005 at 04:06:43 PM MST

Hi rotornuts, Just before the maple blade stuff I started investigating the Lenz/Darrius type mill like an Ropatec rotor. Originally the idea to make a Lenz turbine came from windstuffnow, but after some paper models a ended up with a more Darrius looking thing, later I found out I was making an Ropatec rotor. This is my current design, made out of PS foam It is self starting!! I also added an small alternator under it. This was my original design Its in Dutch. The first picture is also used for my current design. Only deferens is the adjustable  angle of  attack. Current angle of attack is 0. I think my design is self starting because the angle of attack is 0 maybe <0. Greetings, Ray --------------------- You dont know how little you know. till you know enought to know that you still know nothing

Re: Lenz turbine variation pics (3.00 / 0) (#3) by windstuffnow on Sat May 21, 2005 at 05:18:12 PM MST

Pretty slick there Mike!  Fun machines.  Thats what happened with the "coffee can" it wouldn't start but would go like crazy once given a push.  The third blade cures alot of problems, as well it creates a couple.  I was more satisfied with the 3 wing units than any of the 2 wingers.   What's next on the agenda? Have Fun Windstuff Ed Have Fun! Windstuff Ed

Re: Lenz turbine variation pics (3.00 / 0) (#4) by RobD on Sat May 21, 2005 at 06:40:14 PM MST

I think the starting problem is important to address especially in a high cog alternator. It takes more then just to get it going.

Re: Lenz turbine variation pics (3.00 / 0) (#5) by pyrocasto on Sat May 21, 2005 at 09:31:23 PM MST

Would it not be good to just stack two of the turbines 90 degrees off so they start easier?

Re: Lenz turbine variation pics (3.00 / 0) (#6) by Matrix1000 on Sat May 21, 2005 at 10:42:50 PM MST

Thats what I was thinking, perhaps 2/3 stacked on top of each other staggered 1/2 / 1/3 of a turn. Then it might self start yet still retain the same efficiency. [ Parent ]

Re: Lenz turbine variation pics (3.00 / 0) (#7) by pyrocasto on Sun May 22, 2005 at 12:31:24 AM MST

I've seen it done on many comercial turbines and concepts, but I was starting to wonder why hardly any DIYers did it. :) [ Parent ]

Re: Lenz turbine variation pics (3.00 / 0) (#8) by rotornuts on Sun May 22, 2005 at 01:38:53 AM MST

Hi guys, I'm totally mew to the vawt club so I'm still learning and I've learned a few thing here. I think three is probably going to prove better than two. This thing only has a TSR of about .7 so it needs a total redesign. I think the blades are too big and the venturi is in the wrong spot on the upwind side. I think I need to keep the air flow to the outside of the rotor on the upwind side till it comes past 90 degrees or it creates too much drag and the negative pressure behind the unit is wreaking havoc in the two blade design. The ropatec handles things a bit differently but I think some of the same problems may exist there too although I'm starting to see the merit in the delta and the football for the three and two blade designs. BTW Xray that's a very fine unit you built. I'm about to post drawings of my next learning experience with links back to the former posts so plaese give me your thoughts. Mike [ Parent ]

Re: Lenz turbine variation pics (3.00 / 0) (#9) by RobD on Sun May 22, 2005 at 07:20:12 AM MST

This is a project I did a while ago when I was experimenting on small prototypes. I think Sandia said they got around 35% efficiency on it. It is self starting and I planned to stack several on top of each other shifting the phase depending on how many were in the column. (ex. 6 in the column then 360/6= 60 degrees apart) Sandia Patent

Re: Lenz turbine variation pics (3.00 / 0) (#10) by RobD on Sun May 22, 2005 at 07:24:45 AM MST

By the way I tested this small mill to 65 mph mounted on my car. I folded the flashing to prevent fatigue cracks. [ Parent ]

Re: Lenz turbine variation pics (3.00 / 0) (#11) by Matrix1000 on Sun May 22, 2005 at 04:15:25 PM MST

You know it would be cool to put one of these on your tower below your windmill and use those dougnut pipe clamps to keep it on the tower at the height you wanted :P If you put a 5 footer, maybe low, below the guy cables and found some bearings that would fit just right around the 2 -2 1/2 in tower pipe itself, there wouldn't be that much extra stress on the tower I wouldn't think, because it wouldn't have as much leverage. [ Parent ]

Re: Lenz turbine variation pics (3.00 / 0) (#12) by Hanski on Mon May 23, 2005 at 01:16:59 AM MST

I just put my Savonius first time together yesterday. This one is goind to high tree at my cottage. The small genny is going to be on top of the lower half and stator is held by another plywood layer. It starts easily in low wind but I'm conserned about the spinning speed. In a week's time I'll know much more. //Hanski [ Parent ]

Re: Lenz turbine variation pics (3.00 / 0) (#13) by RobD on Mon May 23, 2005 at 06:18:04 AM MST

Looks good Hanski, I'm wondering how the material will hold up over time and weather. What size alternator are you using and what is the cut in speed? Rob [ Parent ]

Re: Lenz turbine variation pics (3.00 / 0) (#14) by Hanski on Mon May 23, 2005 at 01:48:36 PM MST

Rob, Aluminium blades should be OK. Other metal is mostly stainless. I'm little bit worried about the plywood and I'm going to handle the edges somehow. The wooden profiles inside blade got oil treatment. We call it woodoil which is made for outdoor furniture. They might hold two years? Alternator is small 7,6 inches with 12 (24) 0,8inch neos. If I get 100W I'm happy, 50W is OK. Cut in speed is 100rpm. It looks a bit crude but this is my first project ever so please forgive me. //Hanski [ Parent ]

Re: Lenz turbine variation pics (3.00 / 0) (#15) by alcul8r on Mon May 23, 2005 at 02:17:10 PM MST

Nothing to forgive there.... If you have tried anything at all you are ahead of 99.99% of the population. alcul8r KansasWind.com [ Parent ]

Re: Lenz turbine variation pics (3.00 / 0) (#16) by RobD on Tue May 24, 2005 at 07:28:26 AM MST

Looks fine. you don't want to invest a lot of time making a super good looking project when you get started . All my beginning projects were major failures as I'm sure most other builders projects were. Lots of people build big projects for there first mills and unless the project is through someone who has done it before they rarely amount to much. [ Parent ]

Re: Lenz turbine variation pics (3.00 / 0) (#17) by ghurd on Tue May 24, 2005 at 09:17:04 AM MST

I will second that. Even more so if it is not a proven design with plans. G- [ Parent ]

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