ggs theary by gorlov ? + aoa for darius rotors?

[electrondady1]

(blank)

[hvirtane]

Please see:

http://mystic.math.neu.edu/gorban/Gorlov2001.pdf

http://www.mos.org/cst/article/2806/1.html

http://www.recipeland.com/encyclopaedia/index.php/Wind_generator

- Hannu

[electrondady1]

hello hannu, thanks, there is a lot of reading there.i have been spoiled by drag type mills i attempted to make a gorlov turbine by cutting spiral sections from a 20 litre paint bucket. it doesn't work. the rotor profiles will need to be alot more sophisticated.

[aogden]

Interesting research quote from http://mystic.math.neu.edu/gorban/Gorlov2001.pdf

" Conclusions

1 Despite only a narrow class ~1-parameter family! of the flows

has been considered for optimization, the result obtained allows us

to conjecture that the efficiency is maximal when the resistance is

rather small and a large part of the flow ~61 percent! goes through.

In other words, the maximum efficiency could not be noticeably

greater than what was obtained here.

2 The model of a free-flow turbine reveals a new class of problems

about streamlining with partial penetrating through an obstacle;

some of these problems could admit explicit solutions and

could have other applications.

3 The velocity of a flow vanishes at the origin of the proposed

plane model. This makes the model specifically applicable for

two-dimensional propeller-type turbines in free ~nonducted! currents.

The theoretical limit of the efficiency given by the model is

30.1 percent. A number of tests, as well as constructed power

farms, support this thesis in regard to both hydraulic and wind

applications. The efficiency of most water and wind propellers in

free flows usually ranges from 10 to 20 percent. On the other

hand, the three-dimensional hydraulic helical turbine develops an

efficiency of about 35 percent in similar free flow conditions @2#.

This high efficiency might be explained by modeling a 3-D rotor

as a combination of two plane turbines that reflect power contributions

from the front and back parts of the original cross-flow

turbine."

What I find significant is the "35%" efficiency claims for the Gorlov design.

Also here is a commercial wind power helical reference: http://www.turby.nl/downloads/Turby%20ENG.pdf

I have been trying to come up with common materials that could be adapted to make an efficient home sized helical Gorlov wind turbine however with little sucess.  Comments are welcome!

[hvirtane]

I have been trying to come

up with common materials

that could be adapted to

make an efficient home sized

helical Gorlov wind turbine

however with little sucess.

Comments are welcome!

I think that it is possible

to use wood for the blades

and also metal

tubes with wood air foil

pieces. Please see:

http://www.fieldlines.com/story/2004/11/29/10155/497

Also it could be possible to start

with a drum and to cut it open

a suitable way and to build up

'the blades' with some material

for airfoils?

- Hannu

[electrondady1]

 my understanding of the creation of lift is that when the air is split by the rotor the surface on the top or in this case the out side of the is forced to travel a greater distance. the air is required to travel faster and and in so doing the air pressure is reduced.  the rotor is pulled forward.

[hvirtane]

Hi,

here are some ideas

how to make a 'gorlov type' turbine.

The first pictures illustrate

the idea that the blades

are made using metal or plastic tubes.

Airfoil shapes are formed

by covering the tubes with cloth.

If tubes cannot be bent, the airfoil sections will

be longer on the ends of the turbine wheel.

But if the tubes can be bent easily it might

be better to bend them to follow the same

outer circle all the way from one end to one end.

---

The second construction starts with a drum.

The drum is cut open so that only three

rather narrow 'strips' are left from the surface.

These strips will work as the blades of

turbine.

There are in the picture two ideas,

how to make airfoil shapes of the strips.

With the first construction the other ends

of the strips are bent piecemeal. The result

is a J-shaped airfoil, quite similar

as with 'Lenz' turbine.

(www.windstuffnow.com)

With the second construction

in this picture

a metal or plastic tube is fitted

on the leading edge

of the blade strip.

Then the outer side of the blade

is covered with cloth.

I think that the air pressures

will form the airfoils perfectly...  

- Hannu

[electrondady1]

those are good illustrations hannu. two things i noticed with my 20 litre bucket experiment, first,  the whole thing remained quite rigid inspite of having 50% of its surface removed. second , the object looked very pleasing to the eye when it was rotating. i experimented by cutting a slit in some plastic tubing and pushing that onto the leading edge. it responded better but my next step will be to apply the tubing to the out side edge as you have depicted. what are your thoughts on solidity as a percentage? the airfoil profiles you have drawn look "right".  this is where the real science is required , to produce the opptimun ratio between vain thick ness and vain width.  you are considering using cloth as a surface, to allow the airfoil to form itself?  consider this, if the sections of the surface removed to form the rotors (waste)were reapplyed along with the tubing over the remaining sections it would create a profile similar to that which you have drawn.

[hvirtane]

my next step will be to apply

the tubing to the out side

edge as you have depicted.

what are your thoughts

on solidity as a percentage?

---

I think that you could start with

a similar solidity as used with

Darrieus machines. There is available

one really good web page:

http://windturbine-analysis.com/index.htm

In his prototype the guy is using a rather

high solidity Nc/D = 0,42

---

the airfoil profiles you

have drawn look "right".

This is where the real science

is required, to produce

the optimum ratio between

vain thickness and vain width.

You are considering using cloth

as a surface, to allow

the airfoil to form itself?

---

Yes, if you'll use a tube on

the leading edge, I think

that cloth could be a good choice.

I think that the airfoil

would form itself quite well.

One of my friends In Finland

has made HAWT rotor blades

using a tube in the thickest

part of the airfoil, polyurethane

on the leading edge, a steel wire

on the trailing edge and covered the

blades with cloth. They are working

really well.

---

consider this, if the sections

of the surface removed to

form the rotors (waste)were

reapplyed along with the tubing

over the remaining sections

it would create a profile

similar to that which

you have drawn.

---

I think that would

be a good idea.

Do you think to use a tube

on the leading edge?

One more drawing with also some

new suggestions. You might try

using polyurethane on the leading

edge and cloth to cover the vanes?

Which kind of tube have you tried to use?

Metal or plastic?

How thick are the walls of your bucket?

Is the bucket made of metal?

Have you got any pictures of your

prototype?

- Hannu

[electrondady1]

hannu thanks once more for all these links. the paint bucket is probably high density polyetheline. the wall thickness is  2.5mm. they appear to be injection molded , with built in stiffening rings. i have built some drag type mills from this same material, it is very strong. the second airfoil design is the one i will attempt. if i get it to function i will post a photo.

[hvirtane]

Hi,

your material sounds very nice.

I think that also metal buckets

might work.

I'm looking for similar

buckets to make some

experiments, too.

I made yesterday still more

drawings.

This draft above is quite similar

as I made earlier, suggesting developments

of 'WindstuffEd's 'Lenz' turbine. But if

you will make your machine with skewed

vanes like in 'Gorlov' turbine, you can

using waste materials from the bucket,

make 'the crossflow turbine' inside

skewed, too.

Then still another possibility would be to use

waste material from the bucket to fill

the vanes outside with strips. I'm not

sure, if it is necessary to fill the

leading edge rough shapes

with some kind plastic.

The vanes might work well without

filling, too.

- Hannu

[electrondady1]

hannu , my degree is industrial design but i now make my living painting the country homes of wealthy people. finding paint buckets is not a problem for me! you could contact a painting contractor. also, the buckets used in restaurants for  cooking oil. i just purchased (used) 4 large plastic barrels 56cmx92cm . these objects will eventually live exciting lives as windmills! if you wish to see my first windmill look in the wind section under"need a vawt design" . tom w was able to form a link to my video. these gorlov style windmills look very nice when they are spining,if i can make one work, it would be acceptable in an urban setting.

[hvirtane]

my degree is industrial design

but i now make my living painting

the country homes of wealthy people.

finding paint buckets is

not a problem for me!

you could contact

a painting contractor.

That sounds good.

I've been myself as well

looking for such a design,

which could be built

in a factory besides

being a good design

for handicrafts people.

One of my good friends

here, Erkki Nousiainen

has built maybe

the biggest Savonius of

the world using old

paint buckets.

But he opened them and used

the metal plates by bending

them into new shapes.

Please see an old picture

of his Savonius below.

It is about 15 m tall...

I'm becoming quite exited

with this project. I started

to think about 'a gorlov design'

already more than half year ago,

but I've been now outside

my country for a while

and did not have time

and possibilities

for that project.  

I think that some kind of Gorlov

turbine might be the best design

for urban areas.

I will start making a prototype

myself also soon.

I made still a couple of

more design drawings.

I think that using the waste

material from the bucket as

the last picture even

without 'the savonius

vanes' inside will

probably work.

We just need right dimensions

and airfoil shapes.

I tried to see your video,

but unfortunately that

video format doesn't work in

my machine (I'm using

debian gnu/linux). Maybe

you could convert it into

another format?

- Hannu

[electrondady1]

very good work hannu , here's a thought, if at the proto type stage the internal savonas was built in a sub section that could be placed in multiple positions (rotatable and locked) allowing experimentation as to the optimun relationship between it and the out side wings . i think the air coming off the convex side of the savonas could be put to use to trigger or enhanse lift in the gorlov or darius rotors.. perhaps, this relationship has alreadey been documented.

[electrondady1]

i like you friends big windmill. does it make electricity?  it might not be good for urban use !!!! ha!

[electrondady1]

hannu i have no knowlege on how to convert the video to an other format.

you have drawn the gorlov/darious wings to be 1/6 of the surface do you consider this to be optimum.