Wind Turbine Design Project San Jose State University Charles W. Davidson College of Engineering E10 Introduction to Engineering Cali Ferrari, Josh Crummy, Rex Doreza, Ryan Honrado, Tony Do, Milaud Nik-Ahd. E10 Section: 19, Team Number: 2 Instructor: Winston Wang October 22, 2014
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Wind Turbine Design Project
San Jose State University
Charles W. Davidson College of Engineering
E10 Introduction to Engineering
Cali Ferrari, Josh Crummy, Rex Doreza,
Ryan Honrado, Tony Do, Milaud Nik-Ahd.
E10 Section: 19, Team Number: 2
Instructor: Winston Wang
October 22, 2014
i
Abstract:
Given the global strain on the planet’s natural resources, many nations are beginning to
invest more on the development, research, and exploitation of various types of alternative
energies. Specifically, this experiment was focused wind energy. Each group was construct a
unique model-size wind turbine, consisting of an original support structure and custom airfoil
design. Outside materials were permitted in the design of the support structure. The
completed wind turbine was then massed and tested for both stiffness and power generation.
The goal was to create the strongest, lightest and most powerful wind turbine possible.
Particularly, the group discussed in this lab report focused on the application of triangles
when creating the support structure and aerodynamics when designing the airfoil. This group
did use outside materials (yellow pine dowels) when constructing the tower. The turbine
weighed in at 280 grams. In the group’s testing results, an exceptional stiffness was observed
(0.11 mm deflection under a 4.5 Kg load!), whereas rather insufficient power was generated
(780 mW). These results imply that the material choice increased both the mass and stiffness
of the final wind turbine.
The group was able to conclude that the lack of power was due to the design of the
airfoil. By referencing some lab results from an experiment done by aerospace engineering
students UIUC, it is observed the airfoil the group designed was better fit for an aircraft than a
wind turbine, which resulted in the low power generation. Understanding this, the group
suggested that in the future it would be beneficial to be more careful when determining the lift-
to-drag ratio and to assure the optimal angle of attack is reached with respect to the structure
being created.
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Figure 1 - Completed wind turbine for this project (Doreza, 2014)
Table 1 (Ferrari, 2014)
Height 16 5/8 inch Mass 935 grams Max Output Power 780 mW Theoretical Power 4.2 W Stiffness 36.957 Kg/mm
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Table of Contents
Description: Page:
Abstract i
Table of Contents iii
1) Introduction 1
(1.1) Background on Wind Turbines Page 1
(1.2) The Project Page 2
(1.3) Specifications Page 2
2) Theory 3
(2.1) Definitions Page 3
(2.2) Equations Page 3
(2.3) Ideas Page 4
Strength of triangles and pyramids Page 4
Material Page 4
Airfoil and Optimum Angle of Attack Page 6
3) Design and Construction 7
(3.1) Tower Page 7
(3.2) Airfoil Page 9
4) Experimental Setup and Procedure 11
(4.1) Strength and Stiffness Page 11
(4.2) Peak Power Output and Max Efficiency Page 12
Activity 1 Page 12
Activity 2 Page 13
iv
5) Experimental Results 13
6) Conclusion and Recommendations 16
7) References 19
8) Appendices 20
Appendix A Page 20
Appendix B Page 21
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Introduction:
1.1: Background on Wind Turbines
Over the past few decades, there has been an increased focus on the conservation of
Earth’s natural resources. This has motivated many industries to make transitions from
traditional methods of energy production to more environmentally friendly and renewable
sources of energy. Among these alternate methods is a structure that converts wind energy
into electrical energy, more commonly known as a wind turbine. A typical wind turbine is
shown in Figure 1, and its components are further detailed in Figure 2.
In the Figure 10, the readings reported by the deflection meter equates to the
deflection variable Y in equation 2. This exercise has multiple trials. In each trial, the amount of
force is incrementally increased until the maximum amount of force is achieved before failure
of the structure. From the given data, stiffness can be calculated using the following equations:
Deflection Meter
Mass (grams)
Structure
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4.2 Peak Output and Max Efficiency.
The second task of this experiment, is to determine the peak power output and
maximum efficiency of the group’s airfoil design. To setup the experiment, each group is given
a small electric motor in tandem with the blade structure the groups designed two weeks prior
to the testing phase. This task is divided into two activities.
Activity 1:
The first activity is intended to establish the power generation capability of the airfoil by
measuring the relationship between a set of variables. Specifically: Total power in (watts);
total electric potential energy in (volts); total current in (Amps), and Resistance in Ohms (Ω). The
relationship between these components can be defined by Ohm’s Law.
To measure the turbine’s power output, the device is connected to a power meter that
is able to give instantaneous measurements of Watts, Volts, and Amps (appendix A). This
circuit is then connected to a variable load meter called a potentiometer (appendix A), (PoT), to
simulate different load resistance to the generating motor. Data gathered from this exercise
can be used to generate a graph showing the relationship between voltage vs current, and
power vs current. Figure 10 shows examples of these graphical relationships.
3.9A 3.9A
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Figure 10 - These graphs highlight the relationship between Power and current,
and Voltage and Current. These example graphs indicate that at 3.9
amps, the system is at its peak power and energy output. 5v and
2.9watts. (Doreza, 2014)
Activity 2:
The second activity is more qualitative, than quantitative. All the second portion of the
experiment deals with is the question, does the turbine produce enough power to light up a
series of light bulbs. Instead of a PoT, a load box with a series of 6 mini light bulbs and
accompanying switches per light bulb is connected. The purpose of this exercise is to determine
the total number of bulbs the turbine system will be able to power. As each switch is closed
and bulb energized, more load is being put to the system.
At this stage of the exercise, all the data have been gathered and it is possible to
calculate the system’s efficiency. Doing so requires the utilization of the baseline data gathered
in the calibration portion of the experiment. These calculations, graphs, and analysis are
discussed in the next section.
Experimental Results
The group’s blade design didn’t provide the anticipated results, but it still performed
relatively well. The design was slightly angled to cause a twist in the blade that would project
optimal angles at each cross section, so that it could generate the most power from the wind.
The 3-D printer that was used to materialize the blade printed the airfoil design a little rough,
so it was necessary to sand it down for optimum power generation. As shown in Figure 11, with
the wind blowing at 25 mph, our blade was able to give a maximum power of 780 milliWatts
and the blade spun at 4000 RPM. To find the theoretical power we used the formula Power = ½
(ρ)(A)(V)3, with ρ being equal to air density which is 1.2 kg/m3, A being the swept area, which is
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pi times the radius of the blade squared, and V being the winds velocity. When including our
values, Power = ½(1.2 kg/m3)(pi(0.0123192 m)(25)3, which came out to 4.2 Watts.
The structural design of the wind turbine produced extremely good results. The choice
to use yellow pine dowels as opposed to the given balsa wood made a noticeable difference
both in the stiffness and weight of the structure. This is because yellow pine is much stronger
and much more durable than the balsa wood, and therefore did a better job of keeping its
shape when being put under the pressure of the weight applied to it. However, yellow pine is
also heavier, and a greater mass was also observed in the results of this
experiment. Considering the stability of the completed structure in comparison to the
increased in weight, it seems as though the choice of yellow pine was a positive one. The
overall weight of the structure came out to be about 280 grams. The choice to use trusses in
the design of the tower structure contributed positively the stiffness of the structure. The
trusses helped to minimize the load being applied to the rest of the structure. Lastly, small
holes were drilled into the base and the legs of the tower were then glued into the base to
increase stability. The results of this experiment were a displacement of 0.11mm under a 4.5 Kg
load. Due to the limited number of weights available, 4.5 Kg highest load that could applied at
the time, but it is likely that the structure could have supported a lot more weight. When
measuring the stiffness we used the formula k = load/deflection, with the load being 44.13
Newton’s and the deflection being 0.11 millimeters, which equaled 36.957 kg/mm.
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Figure 11 – Group 2’s graphs from data
Mechanical and Structural Measurements a. Tower Height: 16 ⅝ in b. Tower Net Weight: 280 g (Total Assembly(935 g) - Top/Bottom Boards(655 g))
Table 3: Stiffness Measurements
Data Points: Load (Kg) Load (N) Displacement (mm)
1 1 9.81 .02
2 2 19.61 .06
3 3 24.52 .07
4 3 29.42 .09
5 4.5 44.13 .11
2.0 Power Measurements a. Blade to Fan Distance: 430 mm b. Wind Speed: 26.3 mph
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Table 4: Progressive Power Measurements
Light Bulb # (ON)
Voltage Volts (V)
Current I (mAmps)
Power P (mWatts)
Blade Speed (RPM)
0 3.35 236 780 4000
1 3.08 192 580 4738
2 3.26 153 480 4990
3 3.49 112 370 5138
4 2.70 263 690 4390
5 3.64 53 170 5315
6 3.41 84 270 5193
Conclusion and Recommendations
This experiment has shown the importance of understanding the fundamentals of wind
turbines. Through the stiffness of the structure, the design of the airfoil, and materials used, a
better understanding has been instilled to the students who conducted this lab experiment.
After designing and creating the wind turbine, data has shown great stiffness through
the use of yellow pine dowels. By following the pyramid design, the stiffness of the structure
was able to withstand 4.5 Kg of weight while weighing about 280 grams.
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FIGURE 12 - UIUC Maximum Lift-to-Drag Graph.
FIGURE 13 - UIUC Airfoil Design Based on Application.
The power produced by the wind turbine was below average (780 mW). This was due to
the design of the airfoil. The graph made by aerospace engineers of UIUC showed that the
airfoil design was similar to an aircraft’s airfoil (See Figure 13). The lift-to-drag ratio of an
aircraft, designed to move at very high velocities, is very different from the airfoil of a wind
turbine, designed to move at much lower velocities. As Figure 12 shows, an optimal design to
get a maximum lift-to-drag ratio is represented by SG6042 and SG6043.
As a recommendation, one should create a blade design that is a closer match to
SG6042 or SG6043. By following these dimensions, a higher power output will be produced.
Combined with a very strong structure and an airfoil design which maximizes lift-to-drag ratio,
an exceptionally powerful wind turbine can be created.
As of March 5, 2014, the American Wind Energy Association has stated that the wind
power has generated 4.13 percent of all electricity in the America in 2013. Elizabeth Salerno,
Vice President of Industry Data and Analysis for the American Wind Energy Association has
stated that electricity generated from wind power has more than tripled since 2008. As society
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embraces these forms of energy, we can see that renewable energy sources are the way of the
future. The further we investigate and perfect these alternate methods of energy production,
the better results we will create. With determination, society can slowly shy away from foreign
oil.
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Reference.
American wind power reaches major power generation milestones in 2013. (n.d.). Retrieved from http://www.awea.org/MediaCenter/pressrelease.aspx?ItemNumber=6184
Anagnos, T. Solar Project | Engineering 10. Retrieved from
http://engineering.sjsu.edu/e10/labs/solar/
Bailey, R., & Johnson, V. (n.d.). Wind powered electric generator design project. Retrieved from