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Small wind turbine fabrication methods
Method · December 2017
DOI: 10.13140/RG.2.2.20437.86240
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KATHMANDU UNIVERSITY
SCHOOL OF ENGINEERING
DEPARTMENT OF MECHANICAL ENGINEERING
REPORT ON
FIVE DAYS SMALL WIND TURBINE CONSTRUCTION WORKSHOP
Submitted by:
Submitted to:
Anamika Pokharel [31105]
Er. Malesh Shah
Nirajan Ghimire [31133]
Lecturer
DoME
December 2017
TABLE OF CONTENTS
LIST OF FIGURES ............................................................................................................ ii
LIST OF TABLES ............................................................................................................. iii
CHAPTER 1 INTRODUCTION ....................................................................................... 1
1.1
Background ............................................................................................................. 1
CHAPTER 2 METHODOLOGY ...................................................................................... 2
2.1
Methodology ........................................................................................................... 3
CHAPTER 3 WORK ACCOMPLISHED ........................................................................ 4
3.1
Turbine Blades ........................................................................................................ 4
3.2
Metal Works ........................................................................................................... 6
3.3
Constriction of Alternator ....................................................................................... 8
3.4
Assembly .............................................................................................................. 10
CHAPTER 4 CONCLUSION .......................................................................................... 11
APPENDIX ........................................................................................................................ 12
i
LIST OF FIGURES
Figure 1 Small Wind Turbine Labelled Parts ........................................................................ 1
Figure 2:Marking of stations on wood at different distance ................................................. 4
Figure 3: Design and Fabricated wind turbine blade profile ................................................. 5
Figure 4: Alternator frame design and fabricated model ...................................................... 6
Figure 5: Fabricated tail vane with yaw bearing ................................................................... 7
Figure 6: Coil winder die and winded copper coil ................................................................ 8
Figure 7: Casting mold and casted steel plate with magnet .................................................. 9
Figure 8: Assembly of parts of Alternator ............................................................................ 9
Figure 9: Assembly of alternator and wind turbine blade in dummy tower ....................... 10
Figure 10: Configuration of wind turbine electric circuit system ....................................... 10
Figure 11: Installed 600W wind turbine at Mythyal, Palpa ................................................ 11
Figure 12:Wood working .................................................................................................... 12
Figure 13: Casting Resins on magnet and winded coil ....................................................... 12
Figure 14: Balancing and checking Alternator voltage ....................................................... 12
Figure 15: Assembling wind turbine, balancing and checking voltage at installation site . 13
Figure 16: Team behind construction of 600W wind turbine at KUTTC ........................... 13
ii
LIST OF TABLES
Table 1: Minimum dimensions of turbine blade with respect to turbine diameter in mm .... 5
Table 2: Dimension of Blade bank template in mm.............................................................. 5
Table 3: Alternator frame dimension for 2.4 m diameter wind turbine ................................ 6
Table 4: Dimension of Yaw bearing pipe and tail vane in mm ............................................. 7
Table 5: Alternator specifications for 2.4 m wind turbine .................................................... 8
iii
CHAPTER 1 INTRODUCTION
1.1 Background
The small wind turbine construction workshop was held at Kathmandu University Technical
Training Center for five days from 31 October to 4 November, 2017. The main instructor was
Kostas Lataufis, RurERG, National Technical University of Athens and Co-Instructor were
Kimon Silwal, KAPEG and Noasos, RurERG. There were twenty-one participants in the
workshop from diverse academic background and they were actively participated in workshop.
This program was a collaborative initiation of Kathmandu Alternative Power and Energy
Group (KAPEG) and People, Energy & Environment Development Association (PEEDA).
The construction workshop at KUTTC was the second phase of the entire wind turbine
program; first being the 2 days seminar about the theory and construction of small wind turbine
held at Dining Park and Longue, Kathmandu form 29 October to 30 October,2017 and final
being a week-long installation phase at Mityal, Palpa from 7 November to 14 November, 2017.
Figure 1 Small Wind Turbine Labelled Parts
1
CHAPTER 2 METHODOLOGY
2-Days Seminar on Small Wind
Turbine
Introduction on Important aspects
for developing Small wind turbine
Fabrication of Yaw
Bearing and Alternator
Frame
Fabrication of Wooden
Blades
Assembly of Turbine set
in dummy tower
Installation of wind
turbine on tower at site
Making Hybrid system
of wind turbine and solar
with electric circuit
system
Operating a Small wind
turbine
2
Fabrication of Alternator
In above Flow chart, the Methodology for Development and installation of 2.4m diameter
small wind turbine was presented.
2.1 Methodology
The wind turbines built in the workshop are based on the designs of Hugh Piggott. The book
followed for the workshop was “A Wind Turbine Recipe Book” by Hugh Piggott. During the
five days course, a 600W small wind turbine with 2.4m rotor diameter was constructed from
scratch, using simple raw materials like wood for the blades, mild-steel for the mounting frame
and tail vane, copper wire for the coils and ferrite magnets cast in resin for the generator. The
wind turbine was built with subdivided focused groups working in parallel sessions of
woodworking, metalworking and generator fabrication, along with short gathering to share
team feedback on what team members had learned.
Woodworking involved hand carving the blades of the rotor using drawknives and spoke
shaves, planes and chisels. Wood as being very suitable material because of light weight, strong
and resistance to fatigue, so it is preferred to select wood without knots, or small knots.
Metalworking involved fabricating the mild-steel frame to support the generator, blades and
tail, with the use of arc-welding, grinding and drilling techniques. Alternator fabrication
involved winding coils, placing magnets, preparing plywood molds and casting the stator coils
and rotor magnet disks into resin.
Although, most of the course were practical, an introduction to the basic theory of small wind
turbine systems was covered accounting important aspects such as the wind energy resource,
aerodynamics of blades, electromagnetism and alternators, the furling tail system, tower
installation and connection to a battery bank. Apart from these short presentations during the
workshop were done to get idea of each sub-division work at the end. At the site, maintenance
procedure of the small wind turbine and hybrid solar-wind electric system was described.
3
CHAPTER 3 WORK ACCOMPLISHED
3.1 Turbine Blades
Three log of Pine woods were cut and carved to make them airfoil shaped.The blade tip were
made narrower than the root to catch the power of wind when blades were turning fast. Closer
to the root the blades move more slowly and so they should be wider and more steeply angled
to the wind. Since back generates a lift force, pushing the blades back and slowing the wind,
so back is curved like the top of wind.
For the dimensions, the reference book “A Wind Turbine Recipe Book” by Hugh Piggott was
consulted and worked accordingly. Some of the tables consulted for the blade carving are:
(a)
(b)
(c)
Figure 2:Marking of stations on wood at different distance
4
Table 1: Minimum dimensions of turbine blade with respect to turbine diameter in mm
Turbine Diameter
Wood width
Thickness
Length of each blade
1200
95
35
600
1800
95
35
900
2400
125
40
1200
3000
145
45
1500
3600
195
60
1800
4200
225
75
2100
( Source: A Wind Turbine Recipe Book” by Hugh Piggott)
Table 2: Dimension of Blade bank template in mm
Turbine diameter
R
W
W2
X
Stations at:
1200
600
38
150
66
200
1800
900
50
140
87
150
2400
1200
50
200
87
200
3000
1500
63
250
109
250
3600
1800
75
300
130
300
( Source: A Wind Turbine Recipe Book” by Hugh Piggott)
Figure 3: Design and Fabricated wind turbine blade profile
5
4200
2100
88
350
152
350
3.2 Metal Works
Fabrication of Alternator Frame:
The alternator frame had made to support the stub shafts that carries the hub and stator hub.
The frame was supported by yaw bearing. The center of the alternator was offset sideways
from the center of yaw bearing so that the turbine yaw away from the wind under the control
of furling system. The frame of alternator was made from L-section of mild-steel. The stator
was mounted in frame with nuts and bolts.
Figure 4: Alternator frame design and fabricated model
Table 3: Alternator frame dimension for 2.4 m diameter wind turbine
Specifications
Length in mm
Length of upright A
353
Channel pieces B, C
216
End bracket D
10
Position of shaft X
65
( Source: A Wind Turbine Recipe Book” by Hugh Piggott)
Fabrication of Yaw bearing, Furling Pipe and Tail Boom:
As wind direction changes, the wind turbine has to yaw on the top of tower to face wind and
catch its power. So, the Yaw bearing is interface between turbine and tower. The yaw bearing
had been constructed from two mild-steel hollow pieces one inside the other. Heavy piece of
iron plate was welded across the top of larger outer pipes, so that it prevents the turbine from
slipping down.
6
Figure 5: Fabricated tail vane with yaw bearing
Table 4: Dimension of Yaw bearing pipe and tail vane in mm
Yaw Bearing Pipe sizes in mm
Tower top stub
Outer yaw pipe
63mm
80mm
Mild-steel pipe dimensions for Tail vane in mm
Boom length A, Diameter b
1000
Hing Outer C, Diameter D
150
Hinge Inner E, Diameter F
250
( Source: A Wind Turbine Recipe Book” by Hugh Piggott)
7
48.3
60.3
48.3
3.3 Constriction of Alternator
Coil Winding:
Magnetic rotor, stator and magnet rotor were made for which procedure were available in the
reference book. Cooper wires were used to make the coil. The coil was connected in Y series
The most interesting part in the coil making was placing the magnet in the rotor. The magnets
on the steel disk were supposed to be alternate, north, south, north and so that the flux alternates
in the coils. Each time the new fitted magnet was to be the right way up.
Figure 6: Coil winder die and winded copper coil
The magnet were first glued to the surface of a steel disk and then casted in resign and glass
fiber as well, so as to protect them from damage and hold from flying off the rotor. The number
of turns per coil and wire size were chosen from reference book so as to make the make the
coils exactly fit into stator as number of turns of coils control the voltage produced at desired
output.
Table 5: Alternator specifications for 2.4 m wind turbine
Details
Number of disks
Magnet/disk
Number of coils
Weight of wire
12-V coil diameter (mm)
Turns per coil
24-V coil diameter(mm)
Turns per coil
Specifications
2
12
9
3 Kg
1.7
73
2
45
( Source: A Wind Turbine Recipe Book” by Hugh Piggott)
8
Resign Casting:
The magnet attached in steel plate were casted in Ester resins along with accelerator like toxic
peroxide to increase setting time. Talcum powder was mixed in resins to reduced the tendency
of casting to heat up. Casting of winded coil were done in fiber glass along with resign,
catalyst(peroxide) and talcum powder.
Figure 7: Casting mold and casted steel plate with magnet
Alternator assembly:
The alternator was held together by long studs made of threaded rods. The magnet rotor was
first mounted in the hub, then stator was mounted with threated studs. After balancing were
done, second magnet rotor were mounted and tightened with bolts. The alternator was tested
by checking the output voltage in Voltmeter by rotating it in clockwise direction.
Figure 8: Assembly of parts of Alternator
9
3.4 Assembly
All the parts were assembled. The parts were fitted in the hub and the dummy tower was made
where the blades and connections were assembled. The wiring inside the tower was made tough
and flexible to withstand movement of turbine on the tower top. Quick review on the working
mechanism, air foil blades, maintained were thoroughly made at final day of workshop.
Figure 9: Assembly of alternator and wind turbine blade in dummy tower
At the installation side of Mythyal, Palpa, we assist in assembly of Alternator with wind turbine
blades in yaw bearing. We also assist our instructor Kostas Lautifis in balancing the wind
turbine blade to gain much efficiency from air foil blades. In order to make tower easy to raise
and lower, Gin pole was fabricated and installed. Heavy chain were tied around L-section bar,
Anchors were made to support tower by connecting it with heavy wire.
Figure 10: Configuration of wind turbine electric circuit system
10
CHAPTER 4 CONCLUSION
The wind turbines built in the workshop are based on the designs of Hugh Piggott. The wind
turbines can be constructed with the use of common materials, simple manufacturing
techniques and basic tools, providing a low cost small wind turbine for practitioners. Hundreds
of homemade small wind turbines have been constructed worldwide using these designs, and
have proven to be robust, efficient, easy to maintain and quick to repair. Typical applications
of locally manufactured small wind turbines are development projects such as electrification
of village communities, educational projects in universities and schools and sustainability
projects such as renewable energy electrification of eco-villages.
Through the construction of a 2.4m rotor diameter small wind turbine, participants got the
chance to develop practical skills such as woodworking, metalworking and working with
resins, along with skills on installing small wind turbines. Basic theoretical knowledge on wind
energy systems were developed, such as aerodynamics and electromagnetism.
Figure 11: Installed 600W wind turbine at Mythyal, Palpa
11
APPENDIX
Figure 12:Wood working
Figure 13: Casting Resins on magnet and winded coil
Figure 14: Balancing and checking Alternator voltage
12
Figure 15: Assembling wind turbine, balancing and checking voltage at installation site
Figure 16: Team behind construction of 600W wind turbine at KUTTC
13
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