“Design and Analysis of a Windmill Blade in Windmill Electric Generation System”

Devangkumar Desai. Int. Journal of Engineering Research and Application www.ijera.com
ISSN : 2248-9622, Vol. 7, Issue 3, ( Part -2) March 2017, pp.01-05
www.ijera.com DOI: 10.9790/9622- 0703020105 1 | P a g e
“Design and Analysis of a Windmill Blade in Windmill Electric
Generation System”
Devangkumar Desai
Research Assistant and Graduate Student, University of Bridgeport
ABSTRACT
Wind turbine is a standout amongst the most imperative wellsprings of renewable vitality. Wind turbine
extricate active vitality from the wind. A little wind turbine cutting edge was composed and examined in this
work. The power execution of little flat hub wind turbines was mimicked in detail utilizing altered blade
element momentum methods (BEM). Another sharp edge was planned utilizing diverse assault points (i.e.0o
, 5o
,
10o
), distinctive speed (4m/s, 5m/s and 12m/s) and rotor span (0.5m and 1m). From this we discover harmony
length and power yield hypothetically. Likewise, we chose material for proposed sharp edge.
Keywords: Drag co-efficient, Lift coefficient, Wind turbine power coefficient, Maximum wind turbine power
coefficient, Wind turbine power output
I. INTRODUCTION
As of late, wind vitality has attracted more
consideration because of the expanding costs of
fossil fills and enhancing financial intensity of
wind turbines in respect to ordinary era
advancements. Today, wind vitality has been
produced into a develop, focused, and for all
intents and purposes contamination free innovation.
Normally a regular substantial, utility scale wind
turbine can create 1.5 to 4.0 million kWh yearly
and works 70-85% of the time. Worldwide wind
vitality generation set another record in 2011,
achieving 239 GW, 3% of aggregate power
creation. It is anticipated that by 2020 it will
increment to 10% of worldwide power
creation.[1,2]
The American Wind Energy
Association revealed in 2010 that creation of little
flat hub wind turbines would increment quickly
later on because of gigantic request. For the order
of level hub twist turbines, there is no settled
standard. The National Renewable Energy
Laboratory in US characterizes wind turbines
whose appraised power are not more noteworthy
than 100 kW, and whose width are close to 19 m as
little wind turbines. Clausen and Wood (2000)
characterized a little twist turbine as having a most
extreme power yield of 50 kW, and further isolated
little twist turbines into three classifications:
miniaturized scale turbines (most extreme 1 kW);
mid-run (bigger than miniaturized scale ones and
littler than small scale ones), typically 1 kW to 5
kW; and smaller than usual turbines whose power
more prominent than 20 kW. [3]
The innovation of
huge wind turbines has been created well, be that
as it may, little wind turbines require more research
in view of various structures and distinctive
applications from substantial ones.In spite of the
fact that Computational Fluid Dynamics (CFD) has
been creating to investigate optimal design of wind
turbines, the Blade Element Momentum (BEM)
strategy is still connected generally for it is a
straightforward, prompt and successful technique
for little wind turbine plan and execution
examination. [5]
The essential idea of BEM is to
partition the wind turbine edge into areas traverse
shrewd, as appeared in Figure 1 (Burton, 2001),
then compute the strengths on every component
with the supposition that all components are
autonomous from each other. At last, the aggregate
powers and minutes on the sharp edge can be
dictated by the coordination of partitioned strengths
and minutes on each segment [11]
Figure 1 A blade element sweeps out an annular
ring
Another vital angle in wind turbine
research is sharp edge materials. The transfer of
utilized wind turbines cutting edges is a hazardous
issue that scientists everywhere throughout the
world are confronting. Current techniques for wind
RESEARCH ARTICLE OPEN ACCESS

turbine edge transfer incorporate landfill, burning
and restricted reusing.[3]
In any case, clearly no
transfer technique is great. An option that can
moderate a portion of the issues with current
transfer strategies is to create "green" materials to
supplant the customary materials. The venture
Hierarchical Green Nano-Bio composites for Light
Weight and Efficient Wind Turbines Blades was
propelled to investigate new sharp edge materials
from bio-hotspots for little twist turbines with
enhanced power execution.[5]
II. OBJECTIVES
The objective of this project was to design
a new blade for a small wind turbine and predict
wind turbine power output at different wind speeds,
different attack angles and different rotor diameter.
III. BLADE ELEMENT MOMNTUM
THEORY
The BEM was also from blade element
theory, and was developed with these assumptions:
each element is independent of the others, with no
radial interaction, and almost constant axial flow
induction factor.
Airfoil
The airfoil is the most critical and major
component in building a wind turbine sharp edge.
Airfoil qualities will decide the execution of the
wind turbine, communicated regarding CT and CP.
Lift coefficient and drag coefficient of
airfoil are the integral for outlining a wind turbine
and the premier parameters to be considered. These
coefficients rely on upon Reynolds number. In
liquid elements, non-dimensional Reynolds number
is characterized as
where is fluid viscosity, ρ is the fluid
density, and v is the kinematic viscosity, U is the
velocity of fluid passing the airfoil surface, L is the
length of the flow. L will be replaced by the chord
length c in terms of wind turbine blade.
Lift coefficient and drag coefficient could
be measured in two-dimension or three-dimension.
In rotor design, two-dimensional coefficients are
adopted widely. They are defined as followed.[11]
Where is lift coefficient, Cdis drag coefficient, l is
the airfoil span.
The lift coefficient and drag coefficient of
an airfoil are a function of the angle of attack and
Reynolds number. Airfoil behavior in the air flow
is divided into three phases: the attached flow
phase, the high lift/stall development phase and the
flat plate/fully stalled phase. In small wind turbine
design, designers prefer high lift coefficient and
relatively low drag coefficient at low angle of
attack, and try to operate with the airfoil in the
attached flow phase if possible, though some stall-
regulated wind turbines operate in high lift/stall
development phase.[11]
Blade Element Analysis
As shown in figure, the following
relationships among the parameters can be
determined as below[11]
Figure 2 Blade geometry for analysis of wind
turbine
In Figure, θp is area pitch point, θp is
cutting edge pitch edge at the tip, θT is segment
curve edge which is characterized in respect to the
tip, α is the approach, is the edge of relative
wind, dFl is the incremental lift constrain, dFd is the
incremental drag compel, dFN is the incremental
drive typical to the plane of revolution (identified
with push), and dFT is the incremental constrain
digressive to the circle. cleared by the rotor, which
adds to the helpful torque, Urel is the relative wind
speed, U (1-an) is twist speed at edges.Generally
normal load coefficient Cn and tangential load
coefficient Ct are defined as[11]
And σ is the local solidity, defined by:
Where, c is chord length of blade at radius r.

dFN=dT and dQ=dQ, two equations can be
obtained as below:
IV. POWER CALCULATIONS
Design calculation can be followed by step by step
procedure as described below:
is a tip speed ratio used to find , from
we find chord length and axial induction factor
and radial induction factor as described in Betz’s
theory.We also find coefficient of power and
coefficient of thrust. At last we find theoretical
power from equation:[11]
Where, r is blade radius, Ω is angular velocity, U is
stream velocity and is tip ratio
Where, n is number of blades, r local blade ratio, s
is length of downwind and upwind.
and
and
R (m) U (m/s)
(Watts)
0.5 3 6.238
0.5 4 14.75
0.5 5 28.85
1.0 3 24.93
1.0 4 69.10
1.0 5 115.43
1.5 3 56.10
1.5 4 132.98
1.5 5 260
Table 1 Calculation of power from input speed and
radius
V. DESIGN OF BLADE
The blades are perhaps the most important
part of our wind turbine. These wind turbine blade
have airfoil shape. The blade materials are carbon
fiber and aluminum alloy.
Figure 3 The front view of blade with dimension
Figure 4 Side view of blade
Details of NACA 2415 airfoil
The NACA airfoils are airfoil shapes for
flying machine wings created by the National
Advisory Committee for Aeronautics (NACA). The
state of the NACA airfoil is depicted utilizing a
progression of digits taking after "NACA". The
edge NACA 2415 mean: Maximum camber 2% at
40%(0.4) harmony from driving edge with a most
extreme thickness 15% at 30% (0.3) harmonies
from the main edge.
Figure 5 Rotor Details

Material Properties
 Aluminum alloy
Properties:
Density = 2700 Kg/m3
ultimate tensile strength = 3.1 X 108
Pa
Young’s modulus of elasticity = 7.1 X 1010
Pa
Tensile yield strength = 2.8 X 108
Pa
Compressive yield strength = 2.8 X 108
Pa
Coefficient of thermal expansion =2.3 X 10-5
K-1
Poisson ratio = 0.33
 Carbon fiber
Properties:
Density = 1600 Kg/m3
ultimate tensile strength = 4.15 X 109
Pa Young’s
modulus of elasticity = 2.310 X 1011
Pa
Tensile yield strength = 2.3 X 108
Pa Compressive
yield strength = 6.1 X 108
Pa
Length
m
Velocity
m/s
Angle of
Attack
Pressure
(Pa)
0.4 4 0o
11.30
5o
11.43
10o
11.42
5 0o
17.26
5o
17.37
10o
17.36
12 0o
94.75
5o
94.70
10o
96.08
0.9 4 0o
11.98
5o
11.94
10o
12.09
5 0o
18.14
5o
18.15
10o
18.40
12 0o
98.03
5o
98.26
10o
101.70
Table 2 pressure at different length of blade,
velocity and angle of attack
VI. APPLICATION
 To light a 60 Watt bulb
Then energy required:
In that case 1 second is 1/3600 of an hour, 60W is
0.060 kW
So, the energy consumed to light a 60W bulb for 1
second is 0.060 x 1/3600 = 0.00001666kWh
If wind velocity is 4m/s, then power output will be
0.00109576 kWh
Total number of bulbs can be light simultaneously
= = 65 bulbs
0.003522 kWh
Total number of bulbs can be light simultaneously
= =211
 Fan
Bajaj Bahar Deco 1200mm fan consumes 73Watt
In that case 1 second is 1/3600 of an hour, 60W is
0.0730 kW
So, the energy consumed to light a 73W fan for 1
second is 0.073 x 1/3600 = 0.0000202778 kWh
0.00109576 kWh
Total number of fans can be rotated simultaneously
= = 53
0.003522 kWh
Total number of fans can be rotated
simultaneously= =
173
VII. CONCLUSION
The followings are the points concluded from the
project work:
 For the same design mass of aluminum alloy is
higher than the carbon fiber and there is a huge
difference in costing for both materials i.e.,
carbon fiber is more economical.
 0.9m blade is more suitable compared to 0.4m
blade for required power output as higher
pressure is achieved on it.
 Maximum pressure occurs when attack of
angle is 7° (after analyzing 0°, 5° and 10° we
observe that pressure increase from 0° to 7°
and afterward it decreases from 7°to 10°. The
maximum pressure occurs at 7° angle).
 The cl/cd ratio is almost same at 7° attack
angle and 10° attack angle but pressure
difference is higher.
 From this project work we conclude blade
parameters as: Blade length= 900mm Blade
material: Carbon fiber Angle of attack: 7°
REFERENCES
[1] M. Capuzzi, A. Pirrera, P. M. Weaver
“Structural design of a novel
aeroelastically tailored wind turbine
blade” 0263-8231 (2015) Elsevier Ltd.
[2] O. Al-Khudairi, H. Ghasemnejad “To
improve failure resistance in joint design
of composite wind turbine blade
materials” 0960-1481 (2015) Elsevier Ltd.
[3] Erick Y. Gómez U., Jorge A. López Z.,
Alan Jimenez R., Victor López G., J. Jesus
Villalon L. “design and manufacturing of
wind turbine Blades of low capacity using
cad/cam Techniques and composite
materials” (2013) page 682-690.
[4] Jeremy (Zheng) Li “Mathematical
Modeling and Computational Simulation
of a New Biomedical Instrument
Design”International Scholarly Research

Network ISRN Biomathematics Volume
2012, Article ID 256741, 5 pages.
[5] Fangfang Song, Yihua Nia, Zhiqiang Tan
“Optimization Design, Modeling and
Dynamic Analysis for Composite Wind
Turbine Blade”Procedia Engineering 16
(2011 ) 369 – 375.
[6] Jeremy (Zheng) Li “Computer aided
modeling and analysis of a new
biomedical and surgical instrument”J.
Biomedical Science and Engineering,
2011, 4, 119-121.
[7] R. K. Tyagi “Wind Energy and Role of
Effecting Parameters” European Journal
of Applied Engineering and Scientific
Research, 2012, 1 (3): 73-83.
[8] Jeremy (Zheng) Li “Computational
Modeling and Design of a New Open Clip
Surgical Instrument”International Journal
of Surgery,dol:10.1016/j.ijsu.2009.05.012.
[9] Nianxin Ren and Jinping Ou “Dust Effect
on the Performance of Wind Turbine
Airfoils” J. Electromagnetic Analysis &
Applications, 2009, 1: 102-107.
[10] Jeremy (Zheng) Li “Computer Aided
Modeling and Dynamic Analysis of A
New Surgical Instrument”Surgical
Science, 2012.
[11] General Momentum Theory for Horizontal
Axis Wind Turbines Book by Jens
Norkaer Sorensen

“Design and Analysis of a Windmill Blade in Windmill Electric Generation System”

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