Wind: building a vertical axis wind turbine from A to Z

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coucou789456
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by coucou789456 » 07/10/09, 16:45

re

for th, Consult this site that talks about the Magnus effect.

http://www.polytech-clermont.fr/partena ... ienne.html

jeff
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by th » 07/10/09, 23:49

Good evening,

even if my idea does not look very good, nor enchants the crowd : Cry: : Cry: I could not help but think about it.

Let us admit that in the saviolus the wind which bounces on one blade pushes the other with an interesting force (idea which I still have difficulty accepted), it is the basic principle of a saviolus wind turbine. This is a bit like the deflector principle, the wind arrives on the blade and is redirected to the other. why not put deflectors at the entrance, a "giant funnel" to direct the wind towards the active blade. That is to say if instead of making blades 2m (number taken at random) high, this one will have a dimension of 50 cm but will be pushed by the same amount of wind?

On my sketch of drawing, the black cylinder is "full", and the blades are included between 2 full discs also (in gray), in order to force the wind in the blades.

Image


and if indeed a saviolus you get a jump-start wind backward one can also imagine a duct having the same effect as pale (but I find it difficult to gain an unknown):

Image

in all of these images, the deflectors have a random angle, they are not based on calculations. They just serve explained my "idea"
I have no experience in wind turbines, nor in fluid mechanics, so I do not know if deflectors (or a "giant funnel") would be effective, if the losses due to friction or turbulence would not be too important . On the other hand I think (I would be unable to demonstrate it or to prove it) that the fact of "hiding" the blades which go up the wind would make it possible to gain (in fact not to lose) mechanical energy in the wind turbine.

with the basic principle that:

Image

To return to Saviolus, if I understood the different forum or site on the internet, it turns, but does not generate great strength (I do not pretend to have read everything, I can be wrong), far from a wind turbine pale.

some companies are looking elsewhere to make vertical wind turbines. their aim is now to return to the blades without effort, putting in parallel general wind (mechanically or servo).

Finally voila, remains only to make a (promised I try soon), so if anyone has any ideas or advice to give me, I'm interested.

please
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by RV-P » 29/09/12, 17:00

- Hello !
- Looking at this project here:
http://www.windstuffnow.com/main/vawt.htm
, and here :
http://www.windstuffnow.com/main/lenz2_turbine.htm for the plans, I had the idea to optimize it, looking a simple logo.
- Here is the original wind:
Image
- And here is the profile of the blades of the optimized version:
Image
- The design is intended for an overall diameter of 90 cm and mounted on 24 "bicycle wheel rims!
- It can also build in double floor with staggered blades 60 °! Here is the layout paper / cardboard, with a stepper motor-no printer as a generator:
Image
- Note down the image curvature of the blades!
- @ +!
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by dedeleco » 29/09/12, 17:24

Did you study the effectiveness of different types and profiles ???
Otherwise everything is possible without knowing, considering the aerodynamic complexity, rotating courses.

Simple mobile sails seem as effective ???
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by RV-P » 29/09/12, 20:55

- No need for complications: just watch how the wind (which tends to "stick" on a rounded profile) works on a structure.
- So imagine the wind coming from above and working on the blades: the high blade will be driving, its rounded part deflects the wind to the right and begins to "pull" the blade to the left. The left blade is in full force and the right blade is still driving, given the deflection of the wind by the rounding of the high blade which hits the back of the blade!
- I have had my experience of the Air Force access to a lot of studies of the action of wind on different types of aircraft wings and even the blades of jet engines! Why a plane he flies? Not by the pressure under the wing, but DEPRESSION ON the wing! The plane is therefore "sucked" upwards!
- The logo is that of the "SO-VE-LO" brand: three red, green and blue commas inscribed in a white circle!
- Do you really you realize the effectiveness of it? Manufactures the first model!
- @ +!
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by RV-P » 29/09/12, 21:57

- Here: Here the pattern of increased air streams:
Image
- Studied it well!
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by dedeleco » 29/09/12, 23:33

Not by overpressure under the wing, but by DEPRESSION ON the wing! The plane is therefore "sucked" upwards!


It's much more complex than that and we can be wrong !!!

http://en.wikipedia.org/wiki/Lift_%28force%29

As this happens, the starting vortex is shed into the wake, [67] and is provided to Produce A Necessary lift is an airfoil

http://www.arvelgentry.com/techs/The%20 ... action.pdf

http://cordier-phychi.toile-libre.org/phy/portee.html

It is primarily by the inertia and air turbulence forces with change of the inertia of the air movement. deflected down to the end, with speeds down, giving an inertial lift force.
Without inertia effect and swirls (case of high viscosity, such as jam, low speed on small, low Reynolds number, invented in 1883, crucial for aircraft) it is impossible to swim and push the air or water, even with a propeller !!!!



That it is amazing today, Almost 100 Years After the first flight of the Wright Flyer, groups of engineers, scientists, pilots, and others can gather together and-have a spirited debate on how an airplane wing Generates lift. Various Explanations are put forth, and the debate centers on qui explanation is The Most Fundamental.

- John D. Anderson, Curator of Aerodynamics at the National Air and Space Museum

Third - and this is the most serious - the common textbook explanation, and the diagrams that accompany it, describe a force on the wing with no net disturbance to the airstream. This constitutes a violation of Newton's third law. "Bernoulli and Newton in Fluid Mechanics Norman F. Smith The Physics Teacher November 1972 Volume 10, Issue 8, pp. 451 http://tpt.aapt.org/resource/1/phteah/v10/i8


The efficiency of a wind turbine or the power obtained for a given wind depends on its shape, its speed of rotation and is complex.

We must build as many models as countless variants in !!!!

The drawn air streams are idealized, because in reality there are plenty of eddies behind each blade profile that disturb each other and make everything very complex; by destroying the lift (stall).
Moreover these flows strongly change depending on the rotation speed of the blades to the wind, which must have an optimum speed between 1 / 3 (vertical axis in my opinion) of the wind to 5 to 6 time (ends thin blades on horizontal axis) according to the wind turbine structure, which makes large differences of power obtained in the same footprint.

With these swirls, forgotten in the drawing, the upper blade cuts the wind and sends swirls towards the lower ones, especially on the right, instead of gently deflecting the air streams strongly as in the drawing, towards the right wing. , which thus loses its lift, unhooked, by the eddies that make the direction of the wind fluctuate, especially at a not insignificant speed compared to that of the wind (1 / 3 to have significant power), and therefore this blade right up against the wind brakes often, more than it grows.

Also I am skeptical.
1 / 3 of the wind speed is the optimum speed of max power for a blade as the left one, pushed by the wind back straight.
With bearing for a displacement angle with the optimized wind more was, but with the very sensitive settings the speed and angle of the blades, which makes it very complex, as on sailing boat, for each angle relative to the wind , plus stalls with whirlpools, sometimes horrible on boat or windsurfing.
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by RV-P » 30/09/12, 07:38

Dedeleco wrote:It's much more complex than that and we can be wrong !!!

- That's why I made a model! It is much cheaper than true greatness and it refines the theory! But the pattern of air streams corresponds to reality, although I do not have all represented, but only those close to the blades.
- And the original wind turbine with straight blades, what do you think, if you considered the reference site?
- Seeking the profiles of Darrieus wind turbine blades, I came across this picture:
Image
, where we see a symmetrical airplane wing profile because the wind must work on the upstream blades as well as on the downstream blades. We call the Darrieus wind turbine "drag wind turbine" because the power has nothing to do with the surface of the blades!
- Disadvantage: it does not always start one, sometimes we must couple it with a Savonnius to start in light winds.
* I have the Wikipedia article under the eyes: what is written there, I already connnaissais. *
** From what I see, you try to hang on to complicated thoughts to make things simple. I do exactly the opposite: I cling to simple thoughts to make things complicated! **
- @ +!
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by dedeleco » 30/09/12, 13:57

From what I see, you try to hang on to complicated thoughts to make simple things


oh no, the lift of a wing, properly understood, is simple, (inertia effect of the air deviated), although some complicated, inevitably, as any flow of air or liquid is hyper-complex (eddies)For physicists seeking to understand fully (more de140 years before Reynolds 1889 research).
Understand carefully, enables simple, instead of testing constantly blinded more, tests that many others have done before and explained in articles and numerous publications.
It is therefore absurd to reinvent what others have been exploring for decades.

This type of wind turbine with blade or wing sail is the same principle as that of a sailing boat, which for each orientation to the wind (and even wind speed and eddies) has a setting and a orientation of the different sailing !!!

read at least the figures of:
http://fr.wikipedia.org/wiki/Effort_sur_une_voile

very clear on this link to copy taking into account the speed of the blades turning in the wind speed which improves efficiency by turning quickly, changing the settings:
http://fr.wikipedia.org/wiki/Allure_%28marine%29
Thus, the stall is avoided as much as possible.
http://en.wikipedia.org/wiki/Forces_on_sails
http://en.wikipedia.org/wiki/Points_of_sail

Read also:
http://www.amics21.com/laveritat/introd ... rbines.pdf
http://www.amics21.com/laveritat/introd ... olicas.pdf

http://en.wikipedia.org/wiki/Vertical-axis_wind_turbine
http://en.wikipedia.org/wiki/Darrieus_wind_turbine
http://www.sciencedirect.com/science/ar ... 2107000111
http://www.osti.gov/energycitations/pro ... id=6548367
etc ..
Reality is complex from simple principles.

I also read a summary:
http://www.cyberiad.net/library/pdf/we1993_17_2.pdf

Ultra therefore simply and clearly, it dramatically improves efficiency by orienting the blades automatically in function of its angular position relative to the wind and the speed of the blades relative to the wind to have a bearing on the rotating maximum angular positions.
Otherwise the efficiency becomes low for congestion.

The wing profile is much less critical, as the wing is fixed on its support. It is close to an illusion refine this profile, in my opinion.

And failed completely, some have proposed the implementation mechanisms of this orientation, sometimes very simple, even like a sail guided by the wind, which I think is both very simple and it is possible to improve, for better use of the lift, which is almost wasted with fixed blades.

The tapered blades with high finesse with high bearing capacity, (as pictured), increase efficiency, as the picture, allowing to turn much faster, especially if we guide the best with such mechanisms.

Indeed, the impact of wind on the wings must remain limited to avoid dropping to max out most of the rotation, inevitable stall for certain positions.

Otherwise this type of wind turbine gives much less, for a good catch in the wind, without being foldable in case of storm.
I am only repeating what is being studied, measured and wrote that we should not ignore.
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by RV-P » 30/09/12, 20:12

Wikipedia wrote:As a hull roughness plays a role on the performance of the sail. Peckish and microscopic bump have a stabilizing effect and facilitates stalls sailing (transition from laminar to turbulent fashion), they also have an influence on friction losses.

This area is provided in real research object (wind tunnel), it is currently not controlled and therefore not numerically simulated. It appears at high Reynolds number, well chosen roughness will extend the laminar fashion few degrees of incidence more. The behavior is bizarre and for more information see the following reference

- Well, they have not seen, or frowned, scientific reports on the wing grasshopper and shark skin, both of which are rough (and even the locust wing is like a folded piece of paper , so totally anti-aerodynamic)! In nature, we do NOT see shiny surfaces like the wings of gliders, but rough surfaces and precisely, birds, insects and sharks "flat out" beat in performance the best thought of human devices! It's to the point thatthey are trying them on airplane wingsThese rough surfaces !!!
Wikipedia wrote:The stronger the wind, the higher the air particles tend to continue moving in a straight line; So unless it sticks to sailing; So the transition to turbulent mode is near. The Reynolds number is the ratio of the viscosity effect and momentum of the wind. It therefore characterizes the transition from laminar to turbulent fashion mode. Over the Reynolds number is higher the better the performance of the sail

- Hi, hi! Birds and grasshoppers royally care about all our human considerations, including Reynolds number, yet they fly! It's to the point that scientists are revising their judgment and they copy on nature: rough surfaces, ends of vulture wings to separate feathers ... but they can not get rid of complicated calculations who waste their life! ...
- One of the insects that "sticks a glue" to them is the dragonfly! Membranous wings, so far from the profile of plane wings, rough (traversed by black ribs), and four flapping wings! But the performance of this insect is incredible: flight forward, backward, dive, hover, maneuvers to green with envy a high-flying pilot ... !
- So, I "a little" tend to "throw it all overboard" and experience through practice! This is exactly what I did with my model! And I'm doing much better by avoiding "headaches" (and over-consumption of drugs on top of that)!
- Try: you'll see for yourself, instead of "quibbling" about the performance of my wind turbine without having produced the model!
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