Upload
others
View
4
Download
0
Embed Size (px)
Citation preview
Kun Shan University
Undergraduate school of Mechanical Engineering
Final Project
A New Venturi Type - Bladeless Wind Turbine Design Coupled to a Permanent Magnet Generator For Small
Scale Electricity Generation
Undergraduate Students: Rodyn Gilharry 吉洛庭
Carlos Campos Saravia 甘伯斯
Advisor: Song-Hao Wang 王 松 浩
June, 2014
Table of Contents
Abstract ..........................................................................................................................................1
1. Introduction ...............................................................................................................................2
1.1 Permanent Magnet Direct Drive Generator ............................................................................5
1.2 Negative Effects of Wind Turbines ..........................................................................................7
1.2.1 Visual Impact ........................................................................................................................7
1.2.2 Infrasound and Noise ............................................................................................................8
1.2.3 Impact on Wildlife especially birds .......................................................................................9
1.2.4 Shadow Flicker and Blade Glint ...........................................................................................10
1.2.5 Electromagnetic Radiation and Interference ......................................................................10
1.3 Advantages of Venturi ‐ Type Design .....................................................................................11
2. Theory ......................................................................................................................................12
2.1 Wind Power ...........................................................................................................................12
2.2 The Venturi Tube ...................................................................................................................13
2.3 The Permanent Magnet Generator .......................................................................................15
3. Ansys Settings ..........................................................................................................................16
4. Design Procedure .....................................................................................................................18
4.1 Wind Cone Selection...............................................................................................................18
4.2 DESIGN 1 ................................................................................................................................23
4.2.1 Addition of a Venturi Tube ..................................................................................................24
4.2.2 Increasing the Working Area ..............................................................................................28
4.2.3 Final DESIGN 1 .....................................................................................................................31
4.3 DESIGN 2 ................................................................................................................................34
5. Permanent Magnet Generator Design .....................................................................................37
6. Conclusion ................................................................................................................................39
References ...................................................................................................................................40
Appendix A ..................................................................................................................................44
Appendix B ..................................................................................................................................46
Appendix C ..................................................................................................................................47
Appendix D ..................................................................................................................................48
Appendix E ..................................................................................................................................50
Appendix F ..................................................................................................................................51
Appendix G ..................................................................................................................................52
Appendix H ..................................................................................................................................53
Appendix H1 ................................................................................................................................54
Appendix H2 ................................................................................................................................55
Appendix H3 ................................................................................................................................56
Appendix H4 ................................................................................................................................57
Appendix H5 ................................................................................................................................58
1
Abstract:
This Paper presents a design of a bladeless wind turbine that uses the Venturi Tube/Bernoulli's principle to amplify the ambient wind speed so that it may drive a permanent magnet generator. Thus producing energy in areas where harvesting wind power would have not been profitable before. This design incorporates a direct drive method so that the total number of moving parts are reduced, eliminating the need for a gear box and making the maintenance of the wind turbine much easier. The magnet generator used is a coreless one, reducing magnetic drag (cogging torque) thereby increasing the energy output. This design also address many of the environmental concerns presented by conventional wind turbines such as the production of noise and the threat to birds and wildlife.
2
1. Introduction:
Today most of the electricity produced in the world is obtain from the burning of fossil
fuels (see figure 1). This source of energy is not only non-renewable and rapidly depleting but
also causes numerous environmental concerns that in the long run cause more problems than
benefits. Now, because global warming is no longer a warning but an occurrence and its
disastrous effects are being felt globally, most countries are investing more heavily in green
energy. Green energy is obtained from renewable sources and even though they are described as
'Green' that does not necessarily mean that they have no environmental impact. Nuclear energy
produces radioactive waste that takes thousands if not millions of years to decompose. They have
to be stored in a secure facility in boxes that are tested to be 'indestructible', all of this leads to a
lot of spending in the R&D departments. Hydro power is also another great source of energy but
is accompanied by numerous environmental effects. Large Valleys and fields need to be flooded,
completely eliminating the ecosystems in those areas, and also with water shortages and longer
droughts occurring each year, water might soon become too valuable for it to be used as a source
of green energy. The best other renewable energy source to be exploited is Wind Energy. Wind
energy is a very clean energy that poses little environmental risks as can be seen in Table 1.
Fig. 1. Comparison of Energy Sources and Their Usage in Terawatts, 1965-2005 [3]
3
Table 1
Comparison of habitat impacts of wind energy to other energy sources [3].
The world's energy demands are ever increasing (see figure 2), and so the demand for
more reliable and efficient wind turbine systems are also increasing. The clean energy trend that
started mainly in the United States and Europe is now spreading to countries all over the world
with millions of watts of clean energy being supplied to large cities (see figure 3).
Fig. 2. World Energy Demand Growth [3]
4
Fig. 3. Top Ten Wind Power Generating Countries by December, 2011 [2]
One of the main advantages of wind power generation systems in their adaptability, they
can be built in for industrial purposes and many large turbines can be built together side by side
forming large wind mill fields, or they can be made as smaller individual units for domestic use.
This way towns, villages, farms, factories or any person in a remote location can install their own
domestic wind mill and harvest wind power. Individual power units or domestic power units
might be one way in which energy is generated in the future removing the numerous problems
associated with a centralized power station and eliminating miles of power cables that are
currently criss-crossing large cities and towns. Most of the recent designs of small scale wind
turbines incorporate the uses of a Permanent Magnet generator.
5
1.1 Permanent Magnet- Direct Drive Generator
About 1.6 billion people lack access to electricity and many of these are in rural areas so
there is a large potential market for isolated small wind turbines, these wind turbines are usually
less than 5KW and are located in remote areas which are not connected to the main power grid
system [30] [17]. Permanent magnet generators are suitable for small scale wind turbines
because they have a high efficiency, they are categorized into two types because of the direction
of the magnetic flux, the radial type and the axial type (see figure 4).
Fig. 4. The direction of the magnetic flux from the rotor of axial and radial types [22].
Permanent Magnet generators are usually more efficient because of the fact that field
excitation losses are eliminated resulting in major rotor loss reduction, thus high power density is
obtained. Also PM generators have small magnetic thickness which results in smaller dimensions.
For the sake of mechanical simplicity most designs incorporate a direct couple or direct drive
system thereby eliminating the need for gears or complex mechanical parts, eliminating gearbox
failures prolongs the life of the wind turbine and also saves on cost and weight [14] [16] [22] .
Figure 5 shows the general setup of an axial flux permanent magnet generator.
Fig. 5. General arrangement for an Axial Flux Permanent Magnet Generator [17]
6
However, PM generators also have some disadvantages, they do not posses field
excitation control and therefore voltage regulation can be a problem. Using external voltage
control such as large capacitor banks or choosing the turns on the stator windings properly to
produce the anticipated required nominal voltage can be used to correct the problem. Also since
the permanent magnet fields cannot be turned off, there exists the risk of excessive currents in
the case of an internal fault. This could also be corrected by the incorporation of a turbine
governor or dynamic breaking [19]. The Comparison of a PM generator to a conventional wound
rotor type is shown below in Table 2.
Table 2.
Comparison of Wound Rotors and PM Generators
Another Disadvantage of PM generator is Demagnetization. The magnets can become
partially demagnetized by over current or excessive temperature or a combination of both [30].
7
1.2 Negative Effects of Wind Turbines
Even though wind turbines are not thought to pose any major environmental hazards,
there has been extensive studies done on the allegation of Noise Pollution and other assessments
on the effects of large wind turbines on people and their surrounding area. Studies have
concluded that the main negative effects can be listed as follows:
(1) Visual Impact
(2) Infrasound and Noise
(3) Impact on Wildlife especially birds
(4) Shadow Flicker and Blade Glint
(5) Electromagnetic Radiation and Interference
1.2.1 Visual Impact
Although the idea of wind energy is generally well received in public, there is still a
tendency for people not to want a wind farm located close to where they live or other residential
areas. Papers written by Saidur [3] indicate that the visual impact varies according to the wind
energy technology such as colour or contrast, size, distance from residencies, shadow flickering
and the times when the turbines are operational. Recently more and more larger wind turbines
are being built so that they reduce their carbon footprint, this adds to the visual impact since the
towers become more visible from a further distance. The increase of wind turbine size over the
years is represented in Figure 6 with 20MW towers predicted to be built in the near future.
8
Fig. 6. Growth in size of commercial wind turbines [11]
1.2.2 Infrasound and Noise
The most critical environmental impact of wind turbines is noise pollution. Noise is
defined as unwanted sound and sound is characterized by its sound pressure level (loudness) and
its frequency (pitch) which are measured in decibels (dB) and Hertz (Hz), respectively. The
normal human hearing range is from 20Hz - 20,000Hz and anything below 20Hz is referred to as
infrasound [3] [29] [31]. Wind turbines generate sound through mechanical and aerodynamic
means.
The aerodynamic noise is present in all frequencies from infrasound to the audible range,
producing the characteristic 'swishing' sound. Mechanical noise is produced from the motor or
gearbox, but if the turbine is working correctly this noise is reduced to a minimum and should
not be an issue. The main concern with wind turbine noise pollution is its impact on human
health, various studies have been carried out and showed that the health problems associated
with infrasound are [31]:
(a) Effects include annoyance, nuisance and dissatisfaction.
(b) Interference with activities such as sleep, speech and learning
(c) Physiological effects such as anxiety, tinnitus or hearing loss.
9
The relations between wind turbine and its health effects on the general populous is shown in
figure 7.
Fig. 7. Model of the possible relationships between sound exposure, annoyance, sleep
disturbance and psychological distress [6]
1.2.3 Impact on Wildlife especially birds
Wind energy is one of the sources of energy that is most compatible with wildlife and
people around the globe, however there are some reports of bird fatalities by researchers. The
wildlife impacts can be separated into two categories, direct and indirect impact. Direct impact is
when there are bird fatalities due to collisions with wild turbines while the indirect impact are
avoidance, habitat destruction and displacement. Table 3 shows the bird fatality rate in the
United States in 2011.
10
Table 3
Regional and overall bird fatality rates in the United States [3]
1.2.4 Shadow Flicker and Blade Glint
Shadow Flicker occurs when the wind turbine blades rotate in sunny conditions, casting
moving shadows on the ground that results in alternating changes in light intensity that appear to
flick ON and OFF. Blade glint occurs when the surface of the blade reflects the sun's light [29]
[31]. Close to 3% of people with epilepsy are photosensitive and sunlight at flash frequencies
greater than 3Hz has the potential to provoke photosensitive seizures.
1.2.5 Electromagnetic Radiation and Interference
Electromagnetic radiation is a wave of electric and magnetic energy that are
perpendicular to each other and are moving together. Electromagnetic interference from wind
turbines can affect radio communication signals, broadcast radio and television, mobile phones
and radar. Transmission signals from radio or television can get distorted when passing through
moving wind turbine blades. This effect was more present in the first generation of wind turbines
when the blades where made of metal. Today however, most if not all wind turbine blades are
made completely of synthetic material and so this problem is not as pronounced.
11
1.3 Advantages of Venturi - Type Design
There are many reason why the venturi - type design (if functional) would be a much
better wind turbine design than conventional designs. The first is that it does not need high wind
velocity. Since the purpose of the design is to accelerate slow moving air then these type of wind
turbines would be able to be placed in areas where wind energy was not considered before due to
slow wind speeds. The second major advantage over the conventional design is that, due to the
bladeless nature of this wind turbine, the noise pollution factor would be basically eliminated, as
well as the shadow flickering and blade glint. The design allows for the total containment of the
turbine rotor which would lead to less aerodynamic noise and also, if noise is still present, to the
addition of noise insulating materials. The third advantage is the elimination if the wildlife
environmental hazard as well. Since there won't be any blades exposed to the environment, bird
fatalities can be reduced drastically. The fourth major advantage is its mobility and life
endurance. Since this design incorporates a housing that contains the rotor and electric generator,
shielding them from the elements, the life of the unit is expected to be prolonged and the unit
very mobile. Making this design type perfect for domestic applications, by placing it on their
roof tops or it can also be scaled up, making large venturi cones out of concrete to withstand high
wind velocities generated inside. There are also many other minor advantages such as low
manufacturing cost, low maintenance etc. but the main advantages for which this design was
created are stated above.
12
2. Theory
2.1 Wind Power
The wind power Pw in an air stream with a density and a velocity through a cross -
area is:
A wind turbine will develop a power Pt, and Pt/Pw is the conversion efficiency, sometimes
referred to as the power coefficient, mathematically [26] [30]:
So the Larger the swept area the more wind power will be generated. In the Venturi-Type
design the swept area is not the same as in conventional designs, the area is not like that of a
circle but more of a donut, and also the angle through which the air does work is dependent on
the position of the inlet and outlet pipes as shown in figure 8 below. The swept area would then
be: A = (θ/360) π [(R1)2 - (R0)
2]
Fig. 8. Cross section area for working air in venturi - type wind turbine
R1
R0
13
2.2 The Venturi tube
Two equations that were used most extensively throughout this project when coming up
with the design and troubleshooting errors was the Bernoulli's theorem and the equation of mass
conservation or continuity equation as it is sometimes referred to. Bernoulli's theorem is a
statement of conservation of energy for fluid flow and in the case of the venturi tube's internal
flow, this equation is not perfectly accurate as the flow is not completely incompressible but it's
an excellent approximation for the purpose of this design [27]. Mass flow simply explains that
the mass inflow must equal to the outflow and for so if a parameter is increased or decreased
then another parameter must decrease or increase to maintain the conservation of mass.
Therefore if the areas for a given mass flow with velocity V and Pressure P is decreased (i.e. the
flow is constricted), then for the same quantity of mass to pass through a given section in the
same period of time, the velocity of the flow must increase. This in turn reduces the pressure at
the point where velocity is increased.
For and incompressible fluid the Bernoulli's theorem is:
14
where (P/γ) is the static pressure head; (V2/γ) is the velocity pressure head and z is the potential
energy head. If the potential energy head is zero then Bernoulli's equation is reduced to
A typical Venturi Tube has a converging cone on one end and a diverging cone on the other (see
figure 9) . The section where the cone is constricted the most is where the velocity is highest.
Fig.9. Venturi Tube [15]
15
2.3 The Permanent Magnet generator
A PM generator consists of two rotor discs mounted on either side of a non-magnetic,
non conducting stator. the magnets are generally arranged in a N-S-N-S manner
circumferentially round each rotor plate with the North magnet on one plate facing the South
magnet on the other. Magnetic flux permeates the air space between the rotor disc and travelling
one pole pitch before coming back across the air gap. The flux density distribution is
approximately sinusoidal in both the radial and circumferential directions so that the flux density
profile can be described as a sinusoidal hill, described by the equation [14] :
where ĵn is the magnet equivalent current density given by:
and Brem is the magnet remanence, dm the magnet diameter, τ the pole pitch and un = (πn/ τ). This
flux density profile can now be used to derive the flux between the centre of the armature coil
and the radius ra as:
If it is assumed that the armature coil is concentrated at its mean axial position but that
the coil is divided into three segments a,b and c in the radial direction. Then the total flux linkage
and the coil emf are given by:
16
3. ANSYS Settings
All simulations for the wind cones were done using ANSYS fluent. The geometries were
imported from Solidworks as (.IGS) files and a fine tetrahedron mesh was created from the
imported geometries using the mesh modeler. Inlet and Outlet selections were chosen and named
to make the setting of boundary conditions easier when using fluent. The setting for fluent are
shown in the flowing Figures
Fig. 10. ANSYS fluent General Settings Fig. 12. Boundary Conditions Settings
Fig. 11. Model Setting/Turbulence Settings Fig. 13. Solution Methods Settings
17
Fig. 14. Solution Initialization Setting Fig.15. Run Calculation Settings
18
4. Design Procedure
Many steps and simulations were carried out to arrive at the final design for the Venturi -
Type Wind Turbine. Every time a simulation was carried out and a flow phenomena was noted,
an alteration to the design was done in order to correct the problem or to make the design more
efficient. In the end the main desired characteristic that was pursued was high inlet speed in
order to make the turbine spin faster.
4.1 Wind Cone Selection
A wind cone can come in any shape or form, as long as the area is reduced the wind
speed should increase. However, in free stream air a lot of other factor come into play and the
geometry and shape of the cone can be very important. Some can lead to air stagnation, flow
separation or recirculation. For the Venturi - Type design, three cones were considered, a box
shape design (figure 16), a tetrahedron or triangular shape design (figure 17) and a cylindrical
cone shape design (figure 18). Details about the dimensions for the cones can be seen in
Appendix A.
Fig. 16. Square Cone Fig. 17. Tetrahedron Cone
19
Fig. 18. Cylindrical Con
When their front face was set as the inlet with the boundary condition as inlet velocity at
4m/s, all of the designs basically showed the same result with air being accelerated to speed up to
400+ m/s (see figures 19-21).
Fig. 19. Velocity Vectors of Square Cone
20
Fig. 20. Velocity Vectors of Tetrahedron Cone
Fig. 21. Velocity Vectors of Cylindrical Cone
So with the front faces selected as the inlet, all three cones showed almost the same
velocity acceleration, however when the cones where places in a Air Box in which just the front
of the box was selected as inlet, the cylindrical cone showed the most, if any, air circulation
through the cone (see figures 22-25). Therefore the cylindrical cone was selected for the design.
21
fig. 22. Square Cone in Air Box
Fig. 23. Velocity Vectors Of Square Cone in Air Box
22
Fig. 24. Tetrahedron Cone in Air Box
Fig. 25. Cylindrical cone in Air Box
It is believed that the reason why the cylindrical cone was much better at allowing the
flow of air is because, due to its circular nature the angles inside the cone are much smoother and
so wind does not hit the walls and rebound outside again but instead deflects the air in such a
manner that it leads it further inside the cone. While the other square and tetrahedron designs
have flat sides and steep angles that might deflect the air outside rather than further inside.
23
4.2 DESIGN 1
After the choice of cone had been finalized, a design was made in which the cone was
connected to the hub which enclosed the rotor. A vertical outlet pipe was placed at 180°from the
inlet behind the hub to allow for the exit of the air, placing it in a vertical position allowed for a
greater amount of air to exit since after the curve of the hub, the air will already be travelling in
the Y -direction and so the momentum will allow the air to flow out. Figure 26 shows the general
shape of the design and for more dimensions and details see Appendix B. A simulation of air
flow inside the hub is shown in figure 27, with the inlet air velocity at 4 m/s.
Fig. 26. Initial Form of Design 1 Fig. 27. Velocity Vectors inside the Hub
From the simulation it can be seen that the design could be improved. Box 2 shows where
the flow separates and that all the mass does not exit, therefore the system has negative feedback.
This mass of air then flows back around to the inlet, and because more mass is being added to the
inlet then the velocity decreases. In box 1 we can see this decrease at the boundary where the
negative feedback flow meets the inlet flow, a slight change in colour illustrates this change in
velocity (see figure 28).
24
Fig. 28. Negative feedback and Velocity reduction
4.2.1 Addition of a Venturi Tube
To get rid of the problem of negative feedback, a Venturi tube was added to the design to
suck out the remaining air, thereby elminating feedback and maintaining higher velocity at the
inlet. Two models where tested, one where the suction pipe of the Venturi tube was connected to
the outlet pipe (figure 29) and another where the suction pipe was connected directly to the Hub
beside the outlet pipe (figure 30). Simulations were done for the two models (figures 31-34) and
the results compared to select the best model. For more details and dimensions of the Venturi
tube see Appendix C.
Fig. 29. Venturi Tube connected Fig. 30. Venturi Tube connected
to outlet pipe directly to hub
25
The Venturi tube was designed in such a way that a small tube of diameter (D) empties
into a larger tube to diameter (2D) therefore doubling the area. Therefore by the law of
continuity the mass flow will be halved and to try to restore balance it will try to obtain air mass
from another source, thereby causing a suction.
Fig. 31. Simulation for Venturi tube connected to Outlet Pipe
Fig. 32. Close up section of the Hub: Inlet Vel ≈ 340 m/s
26
Fig. 33. Simulation for Venturi Tube connected direct to Hub
Fig. 34. Close up section of Hub: Inlet Vel ≈ 360 m/s
27
After analyzing the simulations it was noted that having the Venturi Tube directly onto
the Hub gave better results than when it is coupled onto the outlet pipe. For one the Inlet velocity
was slightly higher and also having the Venturi tube directly on the Hub produced a nice flow
field as depicted in Box 3, with a higher air velocity being more uniformly spread out across the
working area. This might be explained by the fact that the low pressure area in the venturi tube
causes a suction that accelerates air towards the outlet thus making a more uniform flow field.
Box 4 shows that more air is being removed from the hub since air is coming both out of the
outlet tube and suck out by the venturi, this slight improvement in mass flow might be
responsible for the slight increase in inlet wind speed since negative feedback is reduced.
28
4.2.2 Increasing the Working Area.
For the maximum amount of energy to be transferred from the wind to the rotor, the
working area in which the wind turns the rotor must be increased. The further the distance the
wind pushes the blade the more torque will be generated and as a result more electricity
generated. To increase the working area, the outlet pipe was moved along the circumference of
the hub, increasing the angle from the inlet pipe to the outlet pipe. Two models were designed
and tested, one which had the outlet pipe in a vertical position at 270°from the inlet pipe (figure
35) and another which had it at 225°(figure 36). For more details and dimensions of the models
see Appendix D. Simulation were carried out on both models to determine which one had the
more beneficial characteristics (figures 37-38).
Fig. 35. Model with outlet pipe at 270° Fig. 36. Model with outlet pipe at 225°
29
Fig. 37. Simulation of flow inside model Fig. 38. Simulation of flow inside model
with outlet pipe at 270° with outlet pipe at 225°
From the results it could be seen that the Model with the outlet pipe at 225°was the better
one since the inlet velocity was much higher, approximately 550 m/s (box 5) while the other was
at around 400m/s. Also the Velocity vector plots showed much more uniform high velocity fields
in the second model as shown in Box 6. This is most likely due to the fact that in the first model
with outlet pipe at 270°, the direction of the air flow had already changed dramatically so that
the direction of the outlet pipe and the direction of the flow air flow were perpendicular to each
other. However in the second model the direction of air was almost parallel to the direction of the
outlet pipe so the flow was easier. More air flowing out means less feedback and higher inlet
velocity. Combining the Venturi Pipe from the simulations before to the new design with the
position of the outlet pipe at 225°, we obtain a modified version of DESIGN 1. Below are figures
for the modified model along with a simulation for air flow through the model (figures 39-40).
For more accurate simulations a circle was cut out of the model to more accurately represent the
exposed area to the rotor fins where the air would flow. Simulations showed that after the
modifications only a small percentage of air circulated back to the inlet (box 7) For more details
and dimensions see Appendix E.
30
Fig. 39. Modified Design 1 with Venturi tube and outlet at 225°
Fig. 40. Simulation of Air flow through Modified Design 1
31
4.2.3 Final Design 1
The last modification done on DESIGN 1 was the addition of a third cone to the inlet. This
allowed two mass inflows to be joined in the same area of the inlet pipe and as a result increase
the velocity of the air dramatically. Figure 41 and 45 shows the final setup of the Venturi- type
wind turbine with the outlet pipe in the Y-direction. A simulation for the airflow through the
final design was done (figures 42-44) and for any additional details or dimensions see Appendix
F.
Fig. 41. Final DESIGN 1
32
Fig. 42. Simulation of Final DESIGN 1
Fig. 43. Close up of Hub in Simulation of air flow: Velocity Vector
33
Fig. 44. Pressure Contour for Final DESIGN 1
Fig. 45. Final DESIGN 1 with Pneumatic Turbine
34
4.3 DESIGN 2
After DESIGN 1 was completed, it was tested by placing it in an air box to simulated
outside conditions. The simulation showed to air acceleration whatsoever and the results were
rather disappointing (figure 46). However this might be caused simply because of missing or
misplaced boundary conditions or a general miscalculation of the program. Nevertheless a
different design was created to try to get some results when simulated in an air box. The reason
as to why no air was flowing through the model was thought to be because of the pipes. Due to
the large number of pipes connecting to each other and their relatively small area, the flow might
have been choked. Therefore a design with no to little pipe length would be preferred. Using all
the information learnt from making DESIGN 1, DESIGN 2 was made (figure 47 and 49).
Fig. 46. Simulation of DESIGN 1 in an Air Box
35
Fig. 47. DESIGN 2
The Main difference between DESIGN 1 and DESIGN 2 is that design 2 has the suction
pipe attached to the outlet pipe rather than direct to the hub, also the Venturi Tubes were
improved. This is because running more simulations it was found that for DESIGN 2 in free
stream air, having the suction pipe attached directly to the hub placed it at equal distance around
the hub from the inlet and so it caused the inlet air to split and race up the opposite direction of
rotation. However having it on the outlet pipe not only made the air flow in the correct direction
but also encouraged rotation. A simulation of DESIGN 2 in an air box is shown in figure 48
below, showing air velocity reached up to 60m/s in the hub at free stream. For more details about
DESIGN 2 or for dimensions, see Appendix G.
36
Fig. 48. Simulation of DESIGN 2 in an Air Box
Fig. 49. DESIGN 2 with Pneumatic Turbine
37
5. Permanent Magnet Generator Design
The permanent magnet generator design was based on designs from professor Wang
Song Hao. The design was adopted and incorporated into the wind Turbine design. The PM
generator is a single -sided coreless axial-flux generator, which is cost effective and easy to
produce. The coreless AFPM generator uses one steel rotor disc and one non-magnetic non-
conducting stator disc. The former carries the NdFeB permanent magnets, arranged
circumferentially around the rotor in a N-S-N-S arrangement, as shown in figure 50 (a). The
latter uses PEEK engineering plastic carrying coils to eliminate the cogging torque and to reduce
the iron loss. The pneumatic turbine (figure 51) is then integrated with the rotor disc of the
AFPM generator. However for use in a wind turbine, it would probably be more beneficial to
incorporate more than one layer of magnets and coils so that more energy can be produced.
Therefore Professor Wang's design can be expanded to become a much larger generator.
Fig. 50. Electric Power Generation Unit [34]
Fig. 51 Structure and Angle Pneumatic Turbine [34]
38
The induced voltages for different RPMs and loads is shown in figure 52 below. Figure
53 shows the general makeup of the generator and its electrical circuit equivalent. For more
details about the PM generator see Appendix H-H5.
Fig. 52. Voltages generated at different RPMs [34]
Fig. 53. The general assembly of the Axial Flux Permanent Magnet Generator. [34]
39
6. Conclusion
The aim behind this Project was to develope a new way in which to harvest wind energy.
One that produces less negative side effects than the conventional wind turbines and also one
that works on a different principle than most others. By designing a Venturi -Type Bladeless
Wind turbine generator, the problem or noise pollution and infra-sound generation is not only
eliminated but also wind energy is able to be harvested in areas never considered before and at
much lower altitudes. Now areas where wind speed is low can still benefit from wind energy
because this design uses Bernoulli's theorem and mass continuity to accelerate the air to usable
speeds. The simulations show that these designs are promising and can be functional. There may
still be some minor modifications that can be made to improve the design and make it more
efficient, tweaking the diameter ratios for the cones or extending the length. If more research is
done in this area, this design should be much more cheaper to manufacture and may even be used
as a domestic power source.
40
References
[1] Ahmed, N.A., “A novel small scale efficient wind turbine for power generation”,
Renewable Energy 57 (2013) 79-85
[2] Alam, Firoz., Golde, Steve., “An aerodynamic study of a micro scale vertical axis wind
turbine”, Procedia Engineering 56 ( 2013 ) 568 – 572
[3] Saidur, R., Rahim, N.A., Islam, M.R., Solangi, K.H., “Environmental impact of wind
energy”, Renewable and Sustainable Energy Reviews 15 (2011) 2423–2430
[4] Yiannis A, Katsigiannis., George S, Stavrakakis., “Estimation of wind energy production
in various sites in Australia for different wind turbine classes: A comparative technical
and economic assessment”, Renewable Energy 67 (2014) 230e236
[5] Amr M, Abd-Elhady., Nehmdoh A, Sabiha., Mohamed A, Izzularab., “Experimental
evaluation of air-termination systems blades”, Electric Power Systems Research 107
(2014) 133– 143
[6] Bakker, R.H., Pedersen, E., van den Berg, G.P., Stewart , R.E., Lok, W., Bouma, J.,
“Impact of wind turbine sound on annoyance, self-reported sleep disturbance and
psychological distress”, Science of the Total Environment 425 (2012) 42–51
[7] Tadamasa, A., Zangeneh, M., “Numerical prediction of wind turbine noise”, Renewable
Energy 36 (2011) 1902e1912
[8] Bashirzadeh Tabrizi a, Amir., Whale, Jonathan., Lyons, Thomas., Urmee, Tania,
“Performance and safety of rooftop wind turbines: Use of CFD to gain insight into inflow
conditions”, Renewable Energy 67 (2014) 242e251
[9] McCubbin, Donald., Sovacool, BenjamiN K., “Quantifying the health and environmental
benefits of wind power to natural gas”, Energy Policy 53 (2013) 429–441
[10] Taylor, Jennifer., Eastwick, Carol., Wilson, Robin., Lawrence, Claire., “The influence of
negative oriented personality traits on the effects of wind”, Personality and Individual
Differences 54 (2013) 338–343
41
[11] Tabassum-Abbasi., Premalatha, M., Tasneem, Abbasi., Abbasi, S.A., “Wind energy
Increasing deployment, rising environmenta lconcerns”, Renewable and Sustainable
Energy Reviews 31(2014)270–288
[12] Lindley D., "Venturimeters and boundary layer effects",PhD Thesis,Cardiff: Dept. of
Mech. Eng., Univ. Coll. of South Wales and Monmouthshire, 1966.
[13] Thomas, Karin., Grabbe, Marten., Yuen, Katarina., Leijon, Mats., “A PermanentMagnet
Generator for Energy Conversion from Marine Currents: No Load and Load
Experiments”, International Scholarly Research Network, ISRN Renewable Energy,
Volume 2012, Article ID 489379
[15] Energy Laboratory., “Air Flow Measurements”, ENERGY LABORATORY ME-EM
3220
[16] Aydin, M., S. Huang., “Axial Flux Permanent Magnet Disc Machines: A Review”,
Shanghai University, Shanghai, 200072, P.R. China
[17] Howey, D.A., “AXIAL FLUX PERMANENT MAGNET GENERATORS FOR PICO-
HYDROPOWER”, EWB-UK Research Conference 2009
[18] Muljadi, E., Butterfield, C.P., Wan, Yih-Huei., “Axial Flux, Modular, Permanent-Magnet
Generator with a Toroidal Winding for Wind Turbine Applications”, NREL/CP-500-
24996 UC Category: 1213
[19] Rucker, Jonathan E., “Design and Analysis of a Permanent Magnet Generator for Naval
Applications”, Massachusetts Institute of Technology June 2005
[20] Butler, Kelly., Cancel, David., Earley, Brian., Morin, Stacey., Morrison, Evan.,
Sangenario, Michael., “Design and Construction of a Supersonic Wind Tunnel”,
Worcester Polytechnic Institute JB3-SWT2, March 2010
[21] Zwyssig, C., Kolar, J.W., Thaler ,W., Vohrer, M., “Design of a 100 W, 500000 rpm
Permanent-Magnet”, Power Electronic Systems Laboratory Swiss Federal Institute of
Technology Zurich 8092 Zurich, SWITZERLAND
42
[22] Hideki, Kobayashi., Yuhito, Doi., Koji, Miyata., Takehisa, Minowa., “Design of the
axial-flux permanent magnet coreless generator” Magnetic Materials R&D Center, Shin-
Etsu Chemical Co., Ltd. 2-1-5 Kitago, Echizen-shi, Fukui, Japan
[23] Dorrell, David G., “Design Requirements for Brushless Permanent Magnet Generators
for Use in Small Renewable Energy Systems”, University of Glasgow, Glasgow, G12
8LT, UK
[24] Khan, M. A. S. K., Saleh, S. A., Rahman, M. A., “Generation and Harmonics in Interior
Permanent Magnet Wind Generator”, Power and Energy Research Laboratory Memorial
University of Newfoundland St. John’s, NL, Canada
[25] Aleksashkin, Anton., Mikkola, Aki., “literature review on permanent magnet generator
design and dynamic behavior”, Lappenranta University of Technology, ISBN 978-952-
214-709-7
[26] Jawad, Faiz., Nariman, Zareh., “Optimal Design of a Small Permanent Magnet Wind
Generator for Rectified Loads”, University of Tehran, Tehran, Iran
[27] Baetz, Brandon., Guerieri, Philip., Krell, Travis., Roustopoulos, Theodoros.,
“optimization of Venturi Performance”,Team Precision Air Convey
[28] Flynn Research., Greenwood MO., “Parallel Path Magnetic Technology for High
Efficiency Power Generators and Motor Drives”, Flynn Research Inc
[29] “The Potential Health Impact of Wind Turbines”, Catalogue No. 014894 ISBN: 978-1-
4435-3288-4 500 May 2010 © 2010 Queen’s Printer for Ontario
[30] Chen, J. Y., Nayar, C. V., “A Low Speed, High Torque, Direct Coupled Permanent
Magnet Generator for Wind Turbine Application”, Centre for Renewable Energy
Systems Technology Australia, Curtin University of Technology, GPO Box U 1987,
Perth 6001, Western Australia
[31] Australian Government., “ Wind Turbines and Health”, National health and medical
research council, july 2010
43
[32] Wolfgang, Jitschin., “Gas flow measurement by the thin orifice and the classical Venturi
tube”, Laboratory of Vacuum Technology, Department of Computer Science,
Mathematics and Natural Sciences, University of Applied Sciences, Wiesenstrasse 14,
35390 Giessen, Germany, May 2004
[33] Reader-Harris, M.J., Brunton, W.C., Gibson, J.J., Hodges, D., Nicholson, I.G.,
“Discharge coefficients of Venturi tubes with standard and non-standard convergent
angles “,Flow Measurement and Instrumentation 12 (2001) 135–145
[34] Gaing, Z.L., Wang, S.H., Lin, C.H., Lin, C.M., Chen, C., “Rigorous design and
implementation of an innovative electric generation unit for a portable self-powered lung
air flow meter”, ME Department, Kun Shan University, Tainan, Taiwan
200
R90
R200
225.55
18
2 Appendix A. 1:2 44SCALE DWG NO.
20
0
31.
20°
18
.31
225
75
20
0 17
.71
24.
50°
250
50
1:2 3 Appendix A 45SCALE DWG NO.
100
100
80
80
68°
60.50°
74.64
10
10
123.15
Appendix B41:3 46SCALE DWG NO.
75
22
100
67
30
10
0
147
10
100 102
Appendix C6.11:3 47SCALE DWG NO.
12
3
112
10
10
74.64
60.50°
68°
270°
1:2 5 Appendix D 48SCALE DWG NO.
12
3
112
10
10
74.64
60.50°
68°
225
1:2 5.1 Appendix D 49SCALE DWG NO.
100
100
100
80
67
110
75
100
77.40
30
10
147
1:3 6 Appendix E 50SCALE DWG NO.
100
147
10
2
187
110
1
47
67
100
100
200
200
100
100
30
20
14
R45
52°
R35
7 Appendix F1:3 51SCALE DWG NO.
100
10
0
100
163
217
TRUE R5
R37
54
10
1:2 8 Appendix G 52SCALE DWG NO.
1
2
3
4
5
1:1 Appendix H1 53SCALE DWG NO.
R37
R6
3
40.31
1:1 1
13
R2
2.5
0 1.50
10
12
1.5
0
16.
27
Appendix H 1 54SCALE DWG NO.
2.
20
6
20
53
R28 R1
R34
.50
40°
Appendix H 21:1 2 55SCALE DWG NO.
R21
R7
R6.50
1
50
5
4 2
Appendix H 32:1 3 56SCALE DWG NO.
10
6.75
60° R13
R22
47
R5
R5
47 10
Appendix H 42:1 4 57SCALE DWG NO.
54
54
R10 4 2.50
50
47
4
12
8 52
2.5
0
15.
50
Appendix H 51:1 5 58SCALE DWG NO.