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Design of vertical axis wind turbine for harnessing optimum power
- 1. INTERNATIONALMechanical Engineering and Technology (IJMET), ISSN 0976 –
International Journal of JOURNAL OF MECHANICAL ENGINEERING
6340(Print), ISSN 0976 – 6359(Online) Volume 4, Issue 2, March - April (2013) © IAEME
AND TECHNOLOGY (IJMET)
ISSN 0976 – 6340 (Print)
ISSN 0976 – 6359 (Online) IJMET
Volume 4, Issue 2, March - April (2013), pp. 172-177
© IAEME: www.iaeme.com/ijmet.asp
Journal Impact Factor (2013): 5.7731 (Calculated by GISI) ©IAEME
www.jifactor.com
DESIGN OF VERTICAL AXIS WIND TURBINE FOR HARNESSING
OPTIMUM POWER
1. M.Z.I.Sajid 2. Dr. K. Hema Chandra Reddy 3. Dr.E.L. Nagesh
1
Quba College of Engineering & Technology, Nellore, Andhra Pradesh (India)
2
Registrar, JNTUA Anantapur. Andhra Pradesh (India)
3
Principal Netaji Institute of Engg. & Tech. Hyderabad, Andhra Pradesh (India)
ABSTRACT
Construction of vertical axis wind turbine has been carried out and experiments were
conducted on models simulating slope or wind reducer in a slow speed wind tunnel. The wind
energy depends on wind velocity. For a 300 slope wind reducer wind velocities were recorded
at various heights. Simultaneously, measurements of the velocities were made at equal
heights on plain surface. A micro-mini vane anemometer was used for wind power
measurements. Details of the experimental results and theoretical explanation are presented.
The results show that wind speed increases with reducer starting with 1.35 times at the top of
the reducer. The maximum increase is noticeable at about 300 slopes. Therefore a typical
wind mill constructed about 10 feet height, 300 slope and 10 feet length since the power is
increased by 3.38 times.
KEY WORDS: Concave shaped slope wind reducer, Efficiency, Sloping structure, Vertical
axis windmill and Wind power.
1. INTRODUCTION
The wind energy depends on wind velocity. Wind velocities at different heights were
expressed in terms of the corresponding available velocities at equal heights with and without
reducer turbines. The results show that wind speed increases with reducer, starting with 1.35
times at the top of the reducer. The maximum increase is noticeable at about 300 slopes.
Therefore it is constructed a typical wind mill about 10 feet height, 300 slope and 10 feet
length. Wind energy shall serve as foundation stone and a driving force for the immediate
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6340(Print), ISSN 0976 – 6359(Online) Volume 4, Issue 2, March - April (2013) © IAEME
application of a world energy system driven by renewable energies to supplement fossil and
nuclear sources. In the Annual 11th World Wind Energy Conference 2012 "Community
Power – Citizens’ Power" held in Bonn, Germany, 2012. The conference covered all aspects
of wind utilization, related policies, manufacturing, development, operation as well as
economic and social issues, with a special focus on how to involve citizens in renewable
energy and mobilize them as active beneficiaries. India is the fifth largest primary energy
consumer and fourth largest petroleum consumer after USA, China, and Japan. Despite the
global economic crisis, India’s economy is expected to grow at 6 to 8 % per year. There is an
extreme dependence on fossil fuels like oil, coal and natural gas with considerable risks and
environmental issues.
2. THEORETICAL ANANLYSIS
In general, the value of wind speed mentioned in meteorological data is at a height
about 12.2 meters and this is taken into consideration while calculating the possible wind
power that may be tapped. To know the real gain in field, wind speed has to be found with
respect to the above value. The calculated values are plotted along with a wind profile over a
plain turbine. From the graph it can be seen that the maximum gain is about 1.5 and hence the
power (1.5)3 = 3.38.
To find an answer for frequent directional changes in wind, further experiments were
carried out a curved (concave shaped) 300 model and symmetrical triangular 300 model. In the
curved model wind velocities were measured at the extreme ends and the middle, the increase
was found to be almost sane (about 1.5 times) at about half of the height. The triangular
model gave an increase in wind speed of about 1.4 times at half of the height. These results
show that in coastal areas where wind direction changes in the day and night, symmetrical
300 wind reducer can be utilized. In areas where frequent changes in wind direction occur,
curved wind reducer will be useful. In further experiments a 300 slope model with partial
slant portion gave an increase in wind speed of about 1.3 times. The latter experimental
results may be useful to increase wind speed at the existing windmill sites.
Slope ( θ) Vs Wind Velocity (m/s)
8
6
4
2
0
0 10 20 30 40 50
Fig.1 Slope Vs Velocity
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6340(Print), ISSN 0976 – 6359(Online) Volume 4, Issue 2, March - April (2013) © IAEME
Velocity (m/s) Vs Wind Power (Watts)
500
400
300
200
100
0
5 5.8 6.1 6.5 7.5 7.3 7.2 7.1 6.8
Fig.2. Velocity Vs Wind power
Wind Speed Vs Height of The Escarpment
1.6
1.4
1.2
1
0.8
0.6
0.4
0.2
0
0 0.2 0.4 0.6 0.8 1 1.2
Fig.3. Wind Speed at Different Heights over the Reducer.
In choosing Glass reinforced plastic for the sloping structure the following advantages
were taken into consideration. Glass reinforced plastic is abundantly available in any
developing countries. In a bid to find a cheap material to make sloping structures Glass
reinforced plastics has been chosen. Glass reinforced plastic wind reducer will help to give
smoothness prevents it from rain and also corrosion resistance. Some studies by researchers
reveal, Glass reinforced plastic have been tested and found to have half of the yield strength
of mild steel. It was found that reinforced plastic slab can be designed like steel reinforced
concrete taking permissible tensile strength and bond strength as 24,000 KN/m2 and 350 KN/
m2 respectively. Glass reinforced plastics have been used for windmill blades in Thailand.
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3. PRACTICAL AND ECONOMIC FEASIBILITY
To see the effect of 300 slopes on wind speed, experiments were carried out by placing
slopes of different roughness before a model windmill and increase in wind speed has been
found to be substantial. Though full scale field tests are yet to be conducted, the results of
Bowen and Lindley show that there is good agreement between full scale field measurements
and wind tunnel. Bowen and Lindley conducted field tests on a 13 m high and 260 sloping
escarpment. Hence, it is felt that variation in increase in wind speed as was found on a
sloping model in wind tunnel.
4. THEORETICAL EXPLANATION OF FLOW OVER WIND REDUCER
To predict the change in wind distribution connected with changes in surface
topography, a method has to be evolved which will help in the design of structures. Usually
the existing codes of practice suggest rules for modifying the design wind profile above hills,
but some measurements have shown such hills, but some measurements have shown such
empirical formula are unreliable. Hence, the need for simple theoretical solutions to
boundary-layer flows over surface obstacles. A theory which explains the general features of
the effect of a two dimensional surface hump on a turbulent boundary by Jackson and Hunt
.In further studies Jackson modified the above theories to be applicable to carious escarpment
shapes. According to Jackson, as the vorticity in the outer part of the boundary layer is small,
one can expect the disturbance to the flow there to be approximately irrational. This implies
perturbation caused by a change in surface topography has exactly the same distribution as
the perturbation to a uniform, in viscid flow caused by the same surface shape. Then the
surface can be found using ordinary irrotational theory. Near the surface, changes in viscous
and Reynolds stresses are also to be taken into account. It can be shown that the thickness of
the layer in which stress changes are important is much less than that of the boundary layer,
so that close to the boundary layer in which stress changes are important is much less than
that of the boundary layer, so the problem of an inner boundary layer being driven by an
inner boundary layer being driven by an externally generated pressure gradient. Methods to
deal with the above problem are available. There is fairly good agreement at height (between
19 and 22m) and at other heights some variation is noticeable. A satisfactory explanation for
the variation in theoretical and experimental results is difficult for the simple reason that
some factors were left out in the calculations of experimental results for lack of sophisticated
instruments. Nevertheless the theory gives a broad picture of the prediction technique of wind
over wind reducer. There is still scope prediction
Fig.4. Dimensions of Cone (Reducer) Fig.5. Cone (Reducer)
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6340(Print), ISSN 0976 – 6359(Online) Volume 4, Issue 2, March - April (2013) © IAEME
Fig.6. Dimensions of Blade Fig.7. Blade
Fig.8. Wind Mill Shaft Fig.9. Wind mill assemble
5. RESULTS AND DISCUSSIONS
The existing design of vertical axis wind turbine has low efficiency the modified
reducer with aerodynamic profile increased the efficiency to considerably. The calculated
values are plotted along with a wind profile over a plain turbine. From the graph it can be
seen that the maximum gain is about 1.5 times and hence the power is (1.5)3 = 3.38.
6. CONCLUSION
It can be concluded after the completion of this work that these vertical axis wind
turbines are more suitable for house hold purposes than the horizontal wind turbines and they
can work with a very low wind speed coming from all the directions making them suitable for
urban areas. Till now the Savonius turbine is used for low power generation requirements but
by putting the reducer in this turbine it could be used for large scale power generations also
because of increasing the wind velocity it works more effectively than the classical Savonius
wind turbine in large scale power generations.
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