BMN Christmas eve & Savonius turbine

[Boss]

December 24th 2007

Good Morning

Here it is Christmas Eve already. Dang.

I spent a while this pre-dawn morning wrapping presents by the warmth of the wood heater, quite pleasant, actually. Nothing is like the feel of Christmas when there are little people in the house, but what are we going to do? Bring back the past? I still remember, and that's good enough for me. We have our old fashioned big bulb X-Mas lights up on the front of the house.They look pretty, but they probably draw more current than a Pink Floyd light show. I better go shut them down for the day.

I want to buy a Kill-a-watt meter

http://www.newegg.com/Product/Product.aspx?Item=N82E16882715001

P3 Kill A Watt Electricity Load Meter and Monitor

These are cool because you can plug in individual appliances and log the power consumption of the device over a period of time. I'm dying to see how much current our 35 inch CRT television draws. My plan, if I can call it that, is to have a Kill a Watt meter in hand when I shop for a smaller flat panel LCD television, or monitor (no tuner) since we do not watch broadcast or network TV. In fact as we should all be moving toward energy consumption consciousness, these devices become even more handy. The link to Newegg.com lists the Kill a Watt meter at $19.00.

So, what else is there to talk about on this consumer based holiday? Listening to the car radio on our trip to Colorado made this country boy realize what I've been missing by living such a remote lifestyle. Damn, they barely had time for a Christmas carol between the desperate pleas for people to get out and spend money, locally. Forget about the pesky economy problem. I think the news media was delusional when it said (on the radio) that 35% of the consumers hadn't shopped for Christmas as of Thursday. Right. They forgot, to spend their money??? Or perhaps they are waiting for that Christmas bonus? Hmmm? This country is heading for disaster with the headlights switched off. But hell, it's Christmas, we only have happy thoughts. We want to be giving and warm, but the corporations have other plans for us. Now, in case you are wondering, I didn't buy any impulse items from Wal-Mart as stocking stuffers this year, and it felt good. I think it is the under $10 crap that Wal-Mart is planning on selling this year. They aren't as out of it as the average consumer is. The Business Scrooges know what is happening to our economy, and they damn sure aren't telling the shoppers that their lives are over and they are now slaves to the big box shops.

Anyway, you have heard it all before. We are trying to work our way back to a simpler celebration of Christmas. A place where we have family and friends around to make ornaments, or whatever kind of arts and crafts projects we can think of. Sorry no hints. You'll have to wait until tomorrow morning just like the little ones. I envision an old fashioned style home up on the mountain in an even more remote location for us in the future, off the grid, possibly a two room cabin modestly powered by wind and solar, where we limit the consumer products impact on ourselves.

I have been studying the new book we received from our wind turbine workshop in Colorado. This book is better and has much more depth than the book we bought from Hugh Piggott. The reason I mention this at this point is because of questions on the Internet forums last night concerning towers and axis orientation. Some people are wondering why we don't use the more modern looking VAWT (vertical axis wind turbine) such as the Savonius wind turbine

Savonius wind turbine

From Wikipedia, the free encyclopedia

Schematic drawing of a two-scoop Savonius turbine

Schematic drawing of a two-scoop Savonius turbine

Operation of a Savonius turbine

Operation of a Savonius turbine

Savonius wind turbines are a type of vertical-axis wind turbine (VAWT), used for converting the power of the wind into torque on a rotating shaft. They were invented by the Finnish engineer Sigurd J Savonius in 1922. Savonius turbines are one of the simplest turbines. Aerodynamically, they are drag-type devices, consisting of two or three scoops. Looking down on the rotor from above, a two-scoop machine would look like an "S" shape in cross section. Because of the curvature, the scoops experience less drag when moving against the wind than when moving with the wind. The differential drag causes the Savonius turbine to spin. Because they are drag-type devices, Savonius turbines extract much less of the wind's power than other similarly-sized lift-type turbines. Much of the swept area of a Savonius rotor is near the ground, making the overall energy extraction less effective due to lower wind speed at lower heights.

Savonius turbines are used whenever cost or reliability is much more important than efficiency.

As you may see this design is a drag only wind device. With the design we are building the TSR (tip speed ratio is cubed to the wind. This means that the blades and thus the axial shaft spin at much higher speeds than the wind is actually blowing. We are removing much more energy from the wind than any other devices. So, we are happy. These wind turbines are relatively simple to build for the extra energy they produce. Even though the Savonius design is always pointed into the wind, it can only remove half the wind energy because only one side is facing the wind the other is pushing against the wind.

There ends today's lesson

With all love and everything.

Merry, happy, marvelous Christmas and a warm fuzzy new year too!

Goofily yours

Brian Rodgers

P.S. I had a great piece of history about old Las Vegas but it was messing with the ability to save the newsletter a sure sign that I have too many graphics

Please visit http://www.legendsofamerica.com/NM-LasVegas.html

I may try to fit it in tomorrow

Here is the heading:

Without exception there was no town

which harbored a more disreputable gang

 of desperadoes, and outlaws than

did Las Vegas

- Ralph Emerson Twitchell, historian

[thefinis]

Merry Christmas and sometimes the olds ways were the best but often it is just our memories that make it seem so good. Ah but memories are like a fine wine and grow better with age and tellings.

May your new year be a great one.

Finis

[hvirtane]

Savonius turbines extract much less of the wind's power than other similarly-sized lift-type turbines.

In reality the difference isn't that big:

- Hannu

[DanB]

The chart shows the savonius turbine to be most efficient above TSR 1.  That doesn't make sense to me, I thought they worked at a TSR much lower.  I don't really understand how the savonius could exceed a TSR of 1.

[electrondady1]

only a free spining vawt could have a tsr. of one.

i recall ed mentioning that a tsp of .3 is the optimum power point for a drag type mill.

 

[hvirtane]

The chart is from Gary Johnson's book

'Wind Energy Systems'.

In most of the literature that chart is wrong.

The book is freely available in the Net.

http://www.eece.ksu.edu/~gjohnson/

A well built Savonius isn't a drag device, only.

There is considerably lift, too.

That explains TSR in the chart.

An extract from Gary Johnson's book:

--------------------------

Chapter 1 Introduction 1 17:

The main advantages of the Savonius are

a very high starting torque and simple

construction.

The disadvantages are weight of materials

and the difficulty of designing the rotor

to withstand high wind speeds.

These disadvantages could perhaps be overcome

by good engineering if the turbine efficiency were

high enough to justify the engineering effort

required.

Agreement on the efficiency of the Savonius

turbine apparently has finally been reached a half  

century after its development. Savonius claimed an

efficiency of 31 per cent in the wind tunnel and

37 per cent in free air. However, he

commented:[10]

The calculations of Professor Betz gave 20 % as

the highest theoretical maximum for vertical

airwheels, which under the best of circumstances

could not produce more than 10 % in practical output.

The theoretical and experimental results failed

to agree. Unfortunately, Savonius did not specify

the shape and size of his turbine well enough for

others to try to duplicate his results.

A small unit of approximately

2 m high by 1 m diameter was built and tested

at Kansas State University during the period

1932-1938[6].

This unit was destroyed by a high wind, but

efficiencies of 35 to 40 % were claimed by the

researchers.

Wind tunnel tests were performed by Sandia

on 1.5 m high by 1 m diameter Savonius turbines,

with a maximum efficiency measured of 25 %

for semicircular blades[1]. Different blade shapes

which were tested at the University of Illinois

showed a maximum efficiency of about 35 %[5].

More Savonius turbines were tested

at Kansas State University, with efficiencies

reported of about 25 %[13, 4].

It thus appears that the Savonius,

if properly designed, has an efficiency nearly as

good as the horizontal axis propeller turbine or

the Darrieus turbine. The Savonius turbine

therefore holds promise in applications where low

to medium technology is required or where the high  

starting torque is important. A chart of

efficiency of five different turbine

types is shown in Fig. 8. The efficiency or

power coefficient varies with the ratio of blade

tip speed to wind speed, with the peak value being

the number quoted for a comparison of turbines.

This will be discussed in more detail in Chapter 4.

It may be noticed that the peak efficiencies

of the two bladed propeller, the Darrieus,

and the Savonius are all above 30 %, while

the American Multiblade and the Dutch windmills

peak at about 15 %.

These efficiencies indicate that the American

Multiblade is not competitive for generating

electricity, even though it is almost ideally

suited and very competitive for pumping water.

The efficiency curves for the Savonius and

the American Multiblade have been known

for a long time[6, 10]. Unfortunately, the labels

on the two curves were accidentally interchanged

in some key publication in recent years, with the

result that many authors have used an erroneous

set of curves in their writing.

This historical accident will probably

take years to correct.

----

So it seems to be the case that

Mr. Savonius was anyway right

and people willing to build these

really simple turbines will get

much better power from these machines

than many people have believed.

- Hannu

[tecker]

Think big 55 gal drums two tier .  . The ratio of three to one puts you in a good spot for a 10 to 12 inch dual rotor . Making the tower is the bigest draw back .  

 

[tecker]

I've had good luck building motor coils in to small Vawts . Smaller wind rotors seem to fit into most sites.

[TomW]

Hannu;

In the beginning of this comment you state:



The chart is from Gary Johnson's book

'Wind Energy Systems'.

In most of the literature that chart is wrong.

The book is freely available in the Net.

If the information is wrong, as you say, you are just confusing matters posting it.

Whats the point?

The Grinch.

[luv2weld]

El Jefe

In reference to---I have been studying the new book we received from our wind turbine workshop in Colorado. This book is better and has much more depth than the book we bought from Hugh Piggott.

What is the name of the book? If it's better than Hugh's book, the

rest of us would like to read it too.

Ralph

[hvirtane]

If the information is wrong, as you say, you are just confusing matters posting it.

Whats the point?

The Grinch.

The thing is that in most literature

the information concerning Savonius machines is wrong,

but not in Gary Johnson's book.

Gary Johnson has got it right. That is the point.

In most books the chart (as published above)

is wrong.

The curves of 'american multiblade' and 'savonius'

are changed in most books.

The above published chart is the right one.  

- Hannu

[TomW]

Ahh, OK. Language barrier.

Why I asked, I guess. The statement was unclear to me.

Thanks.

TomW

[boB]

The TSR greater than one just means the power you get out if the turbine is spinning faster than it's peak power TSR.

You would have to MAKE it spin faster than this TSR to get this portion of the curve, but the efficiency and power output would be as shown in the graph if you do that evidently.

Happy Christmas !

boB

[Boss]

Wow, what a fine discussion this turned into

And to think I took the day off and just hung around with my family while this was going on.

Hmmm.

Anyway, twas I who wrote the original text. It is from my morning newsletter.

The name of the book draft which Dan and Dan provided us with is...

Drum roll

Homebrewed Wind Power, By Dan Bartmann and Dan Fink.

Look for it soon in bookstores near you, well maybe not. But they are working on the release version.

Yes, it is quite a bit... for lack of a better word, better, than the book I just bought from Hugh Piggott, titled, How to build a wind turbine.

The Dans have more information  in their book.  Which is good for me, since I read Hugh's book quickly prior to the workshop. In fact, I'm only a couple of dozen pages into it when I read about lift versus drag.

My son-in-law was here visiting two days ago, he is studying for his commercial electrician journeyman ticket. He has been working with 3 phase in commercial office places. He asked me if I knew anything about Wye(star) versus Delta load splitting. I had to say that I only knew what we have discussed at the workshop and over at Axial Flux or one of the other yahoo groups to which I belong.

Because my Internet was down at the time, we looked in Piggott's book first  Nothing there. However the Dans' book panned out right away. I decent paragraph and diagram on page 27. Good enough for us to see how the electricians can pull (2 phase 208?) volts from 470  volt 3 phase circuit without distorting the remaining circuit.

Well, at lest we were talking about it, whether we got it or not is debatable.

The point is, the otherpower book covers a great deal more than Piggott's book did, right out of the shoot.

         

[DanB]

I must jump in now to say - if you actually get to building you'll find some real flaws in that book, it was a 1st draft.  Hughs book that you read is only plans,  he never meant to include much theory.  (if you want lots of good theory get Hughs other book 'Windpower Workshop'.  While our first draft has a bit of theory in there and plans for the 10' turbine (as we built them a year and a half ago) - and a bit more humor perhaps....  and while it's an honor to hear you say you liked our book so much, Hughs stuff is excellent and one of our biggest sources of inspiration.

[richhagen]

Hugh's book Windpower Workshop, I think it is, has lots of theory on blade design and such.  I found it to be educational in my ongoing quest to build better blades. The other book by him that I have is an instruction manual for building specific turbines - also educational if you are building those or similar turbines.  I haven't had the pleasure of reading DANB and DANF's book, but will try to get it as soon as they make it available.  Rich

[TomW]

Boss;

You seem to imply that Fink can write?

I would need to see that myself to believe it.

[Old F]

Tom as I recall Dan B is good with a crayon  : )

Old F

[Boss]

Right? Oh WRITE! Did I say that? Light hearted writing is my favorite. I learned to read with technical manuals, so what the hell do I know about writing? I shall buy Hugh's book "Wind power." I guess I have the axial flux bug. Love this stuff. I finished the Dans' book last night. Yes, it is a draft. Sure it has some typos, but it is damn good reading. The most important part of a story is the content. Humor is crucial to keep people reading through what might otherwise be unfinished. My English Comp 101 professor once told me every story needs an intro, content and a summation.

After reading this book, I didn't feel like anything thing was missing in my understanding.  

 In the preface to Stephen Hawkings book, A brief history of time, he states that his publisher warned him that for every formula in the book he could expect to lose half his reader base. Stephen thought about this, and said there are probably only a few people who understood his work with the math in anyway, nevertheless he would rewrite the book, with words instead of numbers. It turns out that he was able to describe his theories with mostly words, and people such as myself were given a chance to see inside the mind of a genius.

What's my point?

In the metal working section I might have skimmed over the math where they describe the angle of offset of the furling arm to the angle of offset to the hub, but I read on, enthralled.

Good job guys, I enjoyed your book and learned a crap load at the same time.