Transcript VAWT - Real World Engineering - IEEE Real World Engineering

VERTICAL AXIS WIND TURBINE (VAWT)
FOR MICRO-ENERGY GENERATION:
SPINNING STUDENTS’ MINDS
Summary Lecture
Authors:
Betina Baère Campos Neves, MSc [1]
&
Pedro Barbosa Guedes, MSc [2]
[1] Professor
Department of Electrical Engineering
Institute of Engineering of Porto – Polytechnic Institute of Porto (ISEP - IPP); Portugal
[2] Professor
Department of Mathematics
Institute of Engineering of Porto – Polytechnic Institute of Porto (ISEP - IPP); Portugal
OBJECTIVES
Proposition of a hands-on, team-based project
addressed at first-year students that:
• Will encourage student learning through
participation
• Increase student retention through satisfaction
• Improve student confidence through
achievement
• Having meaningful basic context. This means
that those possessing the correspondent
knowledge will have a positive impact on society
& environment while acting as engineering
agents
DIY VAWT 52 W, 12.5 mph
OBJECTIVES
To focus on energy generation where it is most needed, using different
approaches and locations, respecting the environment and contributing
significantly to the well-being of society.
Microgeneration technologies, especially the ones
based on renewables, have the potential to reduce
built environment related CO2 emissions coupled
with reductions in consumers’ electricity costs.
In a best case scenario Small (<100 kW) and Micro
(<10 kW) Wind electricity generation in a built
environment could be equivalent to about 4% of
the domestic electrical demand (UK estimates for
year 2000 consumption reference numbers and
actual wind resource category).
Kazekamome Remote Hybrid Street
Lamp by Hybridyne Power Systems,
Canada
OBJECTIVES
• Small VAWTs – A GOOD POSSIBILITY
• Urban renewable generation – THE NEXT BEST THING
• Engineering spirit – THE KEY TO THE PROBLEM
• Fun but requiring knowledge – CHALLENGES BRING
OUT THE BEST IN EVERYONE
• “Doing is learning” – LEARNING BY DOING SPARKLES
CREATIVITY AND YOU FEEL GOOD ABOUT IT
FIRST STEPS
Existing types of VAWTs
How do they work…
- from an amateur point of view
- from an engineer’s point of view
Low-cost Savonius turbine by
EMAT Ltd, England
Equations and laws are extremely helpful!
They mean less trial and error
and better results!
FIRST STEPS
But still…there is always trial and error.
VAWTs built:
Savonius
- covered
- uncovered
Giromill
- 3, 4 and 6 blades using quartercylinder shaped blades
- 3 and 6 airfoil shaped blades
FIRST STEPS
THE ONES THAT WORKED
Savonius works just fine and has
better performance if covered.
Is self-starting, even at very low
speeds.
Tall models tend to require a
stabilization point on top,
otherwise they will oscillate
far too much.
These models can be good prime
movers for high torque pm
stepper motors if made
taller/bigger…
Our Savonius model, with top and bottom
covers, spinning for testing purposes!
FIRST STEPS
Giromill VAWTs
Airfoil shaped blades work just fine. Other types tried in
the process did not.
It is advisable to build these VAWTs with an uneven
number of blades.
They may sometimes need a push to start if done in a
bigger scale
Rotation is faster than for Savonius but torque is much
smaller
A simple way of doing an airfoil shaped blade is by folding
a piece of PETG or polycarbonate, aligning and holding it,
using a small adjustable workbench structure and, finally,
riveting it underneath the workbench! Loosening the
support system we have a nice symmetrical airfoil blade!
FIRST STEPS
Since Giromill models
were hard to self-start
an hybrid model was
tried out, adding
something new…
It simply got a small
Savonius structure
right in the middle…
and things did
improve!
THE ENGINEERING
EXPERIENCE
Building a Savonius turbine
Testing layout changes on the turbine
Extracting data from tests
Generating electricity with a motor
working as generator
Estimating parameters
What measurements are still missing in
order to get more relevant data out of
this experience - parameters that were
left out for lack of data ? Cp, Ct, …
Details of our
Savonius model
WHAT CAN BE LEARNED FROM
THIS EXPERIENCE
BUILDING: not easy nor immediate but rewarding.
Learned quite some new vocabulary and now I know how bearings and
couplings work. I’ll be able to choose them on my own if I need to.
Aligning the structure: not easy but extremely important to have a smooth
and light rotation. 3 bearings (in 2 levels), to minimize contact and
friction, solved the puzzle. Other solutions didn’t work as good.
The reflector for speed
measurements with an
optical digital tachometer
3 bearings: 2 fixed and
one adjustable, by rotating
the metal bar holding it,
against the axis. A small
screw holds it in place.
IGUS plastic
plain bearing.
Not as good as
3 bearings…
WHAT CAN BE LEARNED FROM
THIS EXPERIENCE
HOW ABOUT ATTACHING THE MOTOR/ GENERATOR TO
THE SHAFT WITHOUT UNBALANCING THE TURBINE?
FLEXIBLE COUPLING!
Standard (expensive) solution
for flexible precision couplings
“Creative engineered solution”:
A small screw (not very visible…)
prevents the garden hose from
rotating inside the shaft.
A small hole in the hose, along with
markings helps inserting, aligning with
shaft hole and fastening with screw.
WHAT CAN BE LEARNED FROM
THIS EXPERIENCE
MEASURING
Equipments: Multimeter, Oscilloscope, Tachometer,
Anemometer… now I know how to use them, what they
are for and have an idea on how they work (I’ll need
some more knowledge to explore them)
Units: Some old ones…some new ones… Engineers speak
a “standard” language!
That’s very useful!
[1]: Digital oscilloscope, 2 channels;
[2]: Digital multimeter;
[3]: Digital optical tachometer
[4]: Digital hand-held anemometer
[1]
[3]
[2]
[4]
[1]
WHAT CAN BE LEARNED FROM
THIS EXPERIENCE
ELECTROMECHANICAL ENERGY CONVERSION
Maybe not easy while you don’t grasp it…
Easy once you start leaning about it.
Addictive once you see your first generator working!
It can only become better from this point onwards!
[1]
[2]
[3]
[1][3] Details on the two LED’s that served as electrical (very visible!) charge. The PM
motor [2] working as generator has 6 wires. Each group of 3 represents one winding,
Example: yellow / green – 1 “full” winding; The orange wire is the “middle point”. We
used 1 “full” winding per LED. The other winding: black / brown; red = middle
WHAT CAN BE LEARNED FROM
THIS EXPERIENCE [1]
THE GENERATOR
WE USED A PM MOTOR AS GENERATOR…
With another schedule and more knowledge
it would be possible to build a generator for
the turbine.
In a real-world application, as far as small
and medium size wind turbines are
concerned, it is usual to have a direct drive
pm generator built exclusively for that
turbine.
[2]
[3]
[1] Coil arrangement for a DIY PM axial flux generator for wind turbines
[2] STAMFORD radial flux PM generator – Wuxi Huaxiang, Ltd. China
[3] PM direct drive axial flux generator assembly by PacWind
WHAT CAN BE LEARNED FROM
THIS EXPERIENCE
NOTIONS AND FORMULÆ
What is wind
Drag and lift – what makes turbines go round
How to evaluate a turbine
Cp
Ct
TSR or λ
Basic electromagnetics in action
WHAT CAN BE LEARNED FROM
THIS EXPERIENCE
From the obtained data it is
possible to estimate the
turbine’s Tip-Speed Ratio
TSR =  =
R
D
=
V
2V
Graphics summarize some of the observations and data
collected
Step Motor with 2 leds load
Step Motor with 2 leds load
5
5
4,5
4,5
4
V rms (half wave)
V rms (half wave)
4
3,5
Fan_speed1
3
Fan_speed2
Fan_speed3
2,5
2
1,5
1
0
25
50
75
100
125
175
200
Step Motor no load
4
5
3,5
4,5
Fan_speed1
3
Fan_speed2
4
Fan_speed3
3,5
2,5
V rms
V rms
150
Speed (r.p.m.)
4,5
2
Fan_speed1
3
Fan_speed2
Fan_speed3
2,5
1,5
2
1
75
100
Speed (r.p.m.)
125
150
175
200
25
50
75
100
Speed (r.p.m.)
0
5
50
Fan_speed2
Fan_speed3
1,5
1
25
Fan_speed1
3
2,5
2
Step M otor no load
0
3,5
1,5
1
0
25
50
75
100
Speed (r.p.m.)
125
150
175
200
125
150
175
200
WHAT CAN BE LEARNED FROM
THIS EXPERIENCE
LOOKING CAREFULLY AT VISUAL DATA
There is more to it than the eye can meet…
In the next months, years, it will all be unveiled …
CONCLUSIONS
WE NEED ENERGY!
WE NEED IT MORE AND MORE!
WE LIVE, CONCENTRATED,
IN TOWNS AND CITIES!
IT IS BEST TO GENERATE ENERGY
RIGHT WHERE IT IS CONSUMED…
WITHOUT BURDENING EVEN MORE
OUR ENVIRONMENT.
SO MUCH NATURAL RENEWABLE POTENTIAL
UNTAMENED AROUND US.
ENGINEERS PROVIDE SOLUTIONS WHERE THEY ARE
MISSING, WHERE THEY ARE NEEDED.
CONCLUSIONS
This ends the 15 day first experience with
engineering.
This lecture only shows a fraction of all the
learning and experimental processes
behind the project.
The great adventure of engineering has
already started.
May you all fully enjoy it!
Thank you!