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Modified Savonius Turbine Construction
By jlebrun84, Section Wind Posted on Sat Feb 23, 2008 at 04:01:23 PM MST
Wind power with a modified Savonius construction

I've been doing a lot of reading on the construction of a Savonius turbine, and have found that most of the research out there says the Savonius rotor is very inefficient. I have been doing some experiments with this turbine because I believe that with a modified construction of the rotor the TSR(tip speed ratio) can be drastically increased. I will post in a later thread pictures of the rotors I have re-designed. Also, I am curious if anyone has heard of using two separate Savonius rotors moving in two different directions to increase the speed of the turbine. I think by doing this in combination with the axial flux generator, the efficiency of this type of turbine can be greatly increased. I really like the design of Verticle axis turbines and believe that overall they hold a key to providing more power than the conventional Horizontal axis turbines because of the torque created from the sail like rotor. If anyone has any feedback on this topic it would be greatly appreciated. Thanks!

Modified Savonius Turbine Construction | 10 comments (10 topical)

Re: Modified Savonius Turbine Construction (3.00 / 0) (#1)
by vawtman on Sat Feb 23, 2008 at 09:07:11 AM MST

Here is a story i did awhile back FYI
http://www.fieldlines.com/story/2006/10/10/232638/13

Re: Modified Savonius Turbine Construction (3.00 / 0) (#4)
by jlebrun84 on Sat Feb 23, 2008 at 10:45:24 AM MST

I read the comments on your story and there was some interesting feedback. While it is true that the rotors spining in different directions would create cogging, I think you could effectively increase the speed of the turbine with the use of two VAWTS spiningin in separte directions with the use of the axial flux generator described on Other Powers pages. By attaching one wind prop, moving in one direction to the rotor with the magnets, you would be able to keep the magnetic field in sync, and by attaching another wind prop moving in a different direction to the stator you would then be able to create the additional speed required to produce power more effeciently. I will post a few diagrams of what I am working on as soon as I have finished drafting.

The other concept I am toying with is a VAWT prop similar to the Savonius but with the addition of two more blades all spaced equally around each other. Please view my photo uploads to see a draft of the prop I designed. I think the blades of this prop will increase the TSR because as the prop turns it two of the blades are always in the wind and compressing air through the center of the prop to aid in turning the other blades.
JNL
[ Parent ]

Re: Modified Savonius Turbine Construction (3.00 / 0) (#5)
by vawtman on Sat Feb 23, 2008 at 11:39:34 AM MST

Jnl
I really don't know much about Sav designs.I think Eds design is great because it allows the wind to pass through it.Its hard to increase the tsr of a turbine needing the wind to push it.My thoughts anywhoo.

I came to the conclusion that the best would be a wide diameter rotor for ease of construction.May cost more in mags but not much.

Have Fun

Mark

[ Parent ]

Re: Modified Savonius Turbine Construction (3.00 / 0) (#2)
by spinningmagnets on Sat Feb 23, 2008 at 09:23:24 AM MST

I think VAWT's are fun and inexpensive to play with. Please continue to experiment and post any results you get, but its my understanding that for electrical generation, you will get more bang for your buck with a conventional 3-blade high-RPM prop.

VAWT's have more torque and lower RPM's, and a few enthusiasts have used a toothed belt or chain to gear-up the PMA to a slightly higher RPM (the extra load will slow the turbine slightly, so twice the gear teeth do not equal twice the RPM)

I have pics of a large 3-barrel Savonius water-pump for third-world irrigation using auto axle bearings.

I have read about a drum Savonious using a bicycle crank to agitate another 55-gal drum as a washing machine (on a Pacific island in WWll).

Here's a small Benesh VAWT that trickle charges a 12-volt battery to power a remote-control motorized gate far from the house grid.

http://www.macarthurmusic.com/johnkwilson/MakingasimpleSavoniuswindturbine.htm

Google "Lenz2" and "windstuffnow"

Re: Modified Savonius Turbine Construction (3.00 / 0) (#3)
by chris psmith on Sat Feb 23, 2008 at 10:13:56 AM MST

got a number of photos of my benesh vawt in my file on this site.
rgds
chris

[ Parent ]

Re: Modified Savonius Turbine Construction (3.00 / 0) (#6)
by spinningmagnets on Sat Feb 23, 2008 at 12:56:08 PM MST

Here's another discussion...

http://www.fieldlines.com/story/2005/11/25/161346/79
counter rotating VAWT pair to increase relative rotor/stator speed

Since strong magnets and copper wire are expensive, and VAWT's are relatively affordable to make, I can see the desire to double the VAWTs and make the stator and rotor counter-rotate to double the apparent magnet speed in slow winds.

Many people aren't allowed to have a HAWT (like me right now) so a VAWT in the back yard may be better than nothing. I think a good comparison might be to compare a VAWT with a chain drive for doubling the speed of the magnets, against the complexity of the two-VAWT/counter-rotating PMA with slip rings.

If you are certain you want to experiment with a counter-rotating PMA, I can imagine building a stacked pair using a shaft within a pipe, or, a side-by-side pair with one being direct drive and the other using a chain.

I think they would both work well-enough, and although my personal preference would be for the single VAWT with standard PMA using chain-drive, I think a counter-rotating PMA would be fun to try. If you do put something together, please post the results!

Re: Modified Savonius Turbine Construction (3.00 / 0) (#7)
by jlebrun84 on Sat Feb 23, 2008 at 01:14:38 PM MST

I am in the process of constructing one of these VAWT's but I am having difficulty finding a shaft big enough and bearings to fit. Do you have any suggestions of where I might be able to attain these materials? I have heard of people using automobile shafts and bearings for a project like this, do you think this is something that might work?
JNL
[ Parent ]

Re: Modified Savonius Turbine Construction (3.00 / 0) (#9)
by spinningmagnets on Sat Feb 23, 2008 at 10:35:09 PM MST

Here's a very common front wheel auto bearing. They are only $12 new at a NAPA auto parts store. I'm sure at a salvage yard you can get a used bearing + disc for ~$15.

I got a short section of common 1-1/2" and 2" pipe from Home Depot (strong and cheaply available in 10' lengths, enough for a 3-drum Savonius), plus I connected them with a bell union. I took it to the NAPA and compared it to common bearings to find a bearing that fit on one end or the other.

This one is a "BR5", and I was assured it came on too many cars to list, such as ford trucks, GM, Dodge, etc. It fits OK, but a little loose on the 1-1/2" pipe, so I may shim it with a wrap of sheet metal.

I don't know if this is the best option yet, this picture (taken just now) is as far as I've gotten. The plan is to have a '68 Ford Mustang disc sit on it and attach a 4-foot-ish wooden disc to the brake disc. (late 1960's Fords have the outer bearing race and the disc as one piece)

I imagine a simple sealed pillow-block bearing on an "L" bracket will be enough for the top. (look at the "variable pitch" pics from lforbes)

I want to identify common, cheap, and robust parts that can be used in a configuration for a VAWT, a 2' Turgo micro-hydro, or a 6' Poncelet water wheel.

I want to be able to raise a 3-drum Savonius on the middle of three sections of pipe (=30') with guy wires from the peak to help stabilize it.

I want it to be break-down-able to fit all the pieces in a normal truck, and for it to trickle charge a remote 12-volt system for LED lights and music.

[ Parent ]

Re: Modified Savonius Turbine Construction (3.00 / 0) (#10)
by spinningmagnets on Sun Feb 24, 2008 at 10:29:59 AM MST

http://www.shopih.com/graphics/00000001/IMG_0232_2.JPG
Here's a pic of a Jeep front disc bearing hub that would fit over the central pipe for the bottom ($50 new, $20 used at pull-a-part)

http://www.shopih.com/graphics/00000001/IMG_0232_2.JPG
Here's some cheap pillow block bearings for the top

Don't know yet if these particular parts will work well together, but this is the general direction I'm blindly stumbling in.

Don't know yet how to capture images like these, and then post them so I don't have to just use links (on a Mac) already having the pic in the post is worth a kilo-word.

[ Parent ]

Re: Modified Savonius Turbine Construction (3.00 / 0) (#8)
by vawtman on Sat Feb 23, 2008 at 01:39:00 PM MST

Oh my goodness that was me before my computer crashed and realized there was another motorhead.
Some of my early motor conversion thoughts also.Ive been to embarrased to look back at them days.LOL

[ Parent ]

Modified Savonius Turbine Construction | 10 comments (10 topical)

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