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#Post#: 152--------------------------------------------------
How the Lynx Wind Turbine Works
By: lynx wind Date: July 31, 2013, 1:44 pm
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What force causes something to move faster than the force acting
on it?
I want to explain in a series of articles what I have learned
about LYNX High Speed VAWTs and how they work. Many people will
disagree and that is fine. (I wont go into what I discovered
about alternators for wind turbines. That is another
discussion.)
When I first got into wind it was because I was searching for an
alternator design that was suitable for low rpm Steam Engines.
That led me to appreciate and enjoy the whole field of wind
power for several years. I took it as a challenge to get a VAWT
to work as well as the best selling AirBreeze HAWT. And when I
had finished (after four years of work) the Gull 160 performs
better than the HAWT, because it can harvest better at the lower
and upper winds speeds.
I started out as most, thinking of wind machines as downwind
machines and the problem of getting the blades to return upwind.
That leads to trying all sorts of contraptions, mechanical
tricks and levers.
Then I started experimenting with "Lift Vawts". I use that term
because it is what we called these types. Lift really is a
misnomer. I now prefer the term "high speed VAWT", because they
run at speeds greater than true wind speed.
There are three distinct modes of operation with these high
speed VAWTs. Each of these is a little different.
1. Startup
2. TSR 1 (blade tip speed ratio 1:1 with wind speed)
3. High speed (TSR +1)
Startup can occur for a variety of reasons, mainly due to the
imbalance of there being three blades around a 360 circle.
There will always be more blade on one side than the other. It
can startup due to drag, turbulence or suction.
Suction? Before I answer that let me explain the main force
that makes these turbines work.
Coanda Effect
Take a look at these videos and I will explain more in future
articles. I have also done this testing with wind tunnel
testing on the blades I use. The biggest force is on the upwind
leg of the rotation. The blade tries really hard to get its TE
into the airstream. Eventually, at higher speeds, each blade is
trying to move into the high speed airstream that surrounds the
VAWT.
HTML http://youtu.be/TI-Nq9IIdMw
HTML http://youtu.be/TI-Nq9IIdMw
HTML http://youtu.be/AvLwqRCbGKY
HTML http://youtu.be/AvLwqRCbGKY
#Post#: 154--------------------------------------------------
Re: How the Lynx Wind Turbine Works
By: lynx wind Date: August 1, 2013, 7:48 am
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Excerpt from a great article - Coanda Effect: Understanding Why
Wings Work -
HTML http://karmak.org/archive/2003/02/coanda_effect.html
HTML http://karmak.org/archive/2003/02/coanda_effect.html
"I wish I could send this essay to the 6th grade science teacher
who could not take the time to listen to my reasoning. Here's
what happened: he sent me to the principal's office when I came
in the next day with a balsa model plane with dead flat wings.
It would fly with either side up depending on how an aluminum
foil elevator adjustment was set. I used it to demonstrate that
the explanation the class had been given must have been wrong,
somehow. The principal, however, was informed that my offense
was "flying paper airplanes in class" as though done with
disruptive intent. After being warned that I was to improve my
behavior, I went to my beloved math teacher who suggested that I
go to the library to find out how airplanes fly--only to
discover that all the books agreed with my science teacher! It
was a shock to realize that my teacher and even the library
books could be wrong. And it was a revelation that I could trust
my own thinking in the face of such concerted opposition. My
playing with model airplanes had led me to take a major step
toward intellectual independence--and a spirit of innovation
that later led me to create the Macintosh computer project (and
other, less-well-known inventions) as an adult."
AUTHOR'S BIOGRAPHY
Jef Raskin was a professor at the University of California at
San Diego and originated the Macintosh computer at Apple
Computer Inc [Levy 1994; Linzmayer 1994]. He is a
widely-published writer, an avid model airplane builder and
competitor, and an active musician and composer.
Here is another interesting video to ponder
HTML http://youtu.be/mtIo6nWDXnU
HTML http://youtu.be/mtIo6nWDXnU
#Post#: 163--------------------------------------------------
Re: How the Lynx Wind Turbine Works
By: ldissing Date: August 5, 2013, 10:41 am
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So, the coanda effect happens on the blades....but also happens
on the spinning turbine which appears as a "solid" object to
high wind speed which would cause it to turn even faster?
#Post#: 164--------------------------------------------------
Re: How the Lynx Wind Turbine Works
By: lynx wind Date: August 5, 2013, 11:52 am
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Notice in the above video still that there is nothing happening
(no force except atmospheric pressure) on the leeward side of
the ping pong ball. What that means is, there is no water
flowing on the outside of the ping pong ball. This doesn't
happen in nature very often. For instance it would be
impossible for an airplane wing to experience this condition.
With the VAWT, wind does blow either side of the blade at first
until TSR 1 is reached and then most of the exiting air flow is
directed out towards the perimeter. This why the blade set
angle is important. You will notice the TE lays right on the
diameter line.
All the air that moves closely past the blade is compressed off
the TE as a band. The next blade enters this band and the TE
tries to pull into the airflow. At TSR of +1.5 I have seen tell
tales placed on the blades blowing back towards the diameter
line all the way around.
#Post#: 218--------------------------------------------------
Re: How the Lynx Wind Turbine Works
By: ldissing Date: August 11, 2013, 9:45 am
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Why wouldn't more blades cause an even bigger coanda effect once
it is up to TSR?
#Post#: 221--------------------------------------------------
Re: How the Lynx Wind Turbine Works
By: lynx wind Date: August 11, 2013, 4:43 pm
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That is a great question and makes us think hard.
There is only so much power in the wind for a given swept area.
Theoretically the most you can get out of the wind is 57% (the
Betz limit). How you extract the power is a wide open field
with many different machines out there.
So with this type of VAWT you probably could add some blades.
But the power each blades develops isn't necessarily additive.
Each blade would add some drag and develop torque. So while you
could add blades until you almost form a cylinder you would
start to lose the lever length achieved with a longer chord.
And it gets harder to achieve the high torque geometry when
adding more and more blades.
Timing is crucial as well. Clean airflow coming off one
trailing edge needs to arrive at the next oncoming blade at just
the right time.
Also the Gull line of VAWTs are designed for self starting.
#Post#: 227--------------------------------------------------
Re: How the Lynx Wind Turbine Works
By: ldissing Date: August 13, 2013, 11:25 am
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Will you please define "self starting"?
Thanks,
Leroy
#Post#: 228--------------------------------------------------
Re: How the Lynx Wind Turbine Works
By: lynx wind Date: August 13, 2013, 11:48 am
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It used to be thought that VAWTs wouldn't self start, meaning
they would just sit there not turning in the wind. There were
all sorts of schemes to get them started with motors, etc...
I found that with good design these VAWTs will self start (start
turning and running up to high rpm) in even the lowest winds.
#Post#: 248--------------------------------------------------
Re: How the Lynx Wind Turbine Works
By: ldissing Date: August 17, 2013, 12:45 pm
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That is what I thought you might say. BTW, my build of your
DIY VAWT self started the other night. I did not "push" it to
get it going.
Leroy
#Post#: 1448--------------------------------------------------
Re: How the Lynx Wind Turbine Works
By: lavaland Date: February 5, 2014, 7:12 pm
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my Gulls have not had any trouble getting started and quickly
ramping up to speed.
it doesn't take much breeze to get'em started spinning
and
not much more to get them to electric production RPMs
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