lab-x

Wind Turbine Lab Report

Submitted to: Instr. Dr. Kecskemety

GTA S. Patankar

Created by: Team O

Joshua Rogers Ian Campbell

Brooke Robinson

Engineering 1181 The Ohio State University

Columbus, OH 12 November 2015

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Executive Summary

This Wind Turbine Lab includes a series of experiments done using a wind tunnel and wind turbines, with results and a discussion of the results. The insights gained from the experiments were then used to solve a real world problem. The purpose of the experiment was to first better understand the relationship between different aspects of wind and pressure, as well as between wind and the performance of wind turbines. It was also to determine whether or not a single wind turbine could power a housing complex of forty houses. These relationships include the effect of wind on pressure, which can be seen to fluctuate based on wind velocity and a distance radially from the center of the wind tunnel. More importantly, the performance of the wind turbine was effected by the angle at which the blades were placed as well as the wind velocity and design of the propeller. The most effective angle of the propellers was 30°. The turbine performed equally well at all of the tested wind velocities. The most effective blade design was Ian’s blade. This design was the sharpest and most slender of the three designs tested. Our data supports using a 3-blade propeller at an angle 30° to produce the highest power output.

These experiments have significant implications, for they help to better understand the best design to use when constructing wind turbines. They also show that the turbines work just as well at many different wind velocities, which helps to prove that using turbines to harvest wind energy is a feasible and effective way to produce energy.

After discovering these relationships, it was determined whether a wind turbine of 77m diameter in a constant 7m/s wind velocity could power a housing complex of forty houses. It was determined that one turbine would be more than sufficient to power the houses.

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Table of Contents

Introduction …………………………………………………………………………………………………………………..…………………..…. 4

Experimental Methodology ……………………………………………………………………………………………….……………………4

Results ……………………………………………………………………………………………………………..………………………….…………6

Discussion …………………………………………………………………………………………………..……………………………..……….. 10

Conclusion & Recommendation ……………………………………………………………………………………………………………12

Individual Conclusion – Josh ………………………………………………..……………………………………………………..………..13

Individual Conclusion – Ian ……………………………………………………………………………………………………………….…..14

Individual Conclusion – Brooke ………………………………….………………………………………….……..…………………..….15

References.....………………………………….……………….……………………………………………………………….………………....16

Appendix ………………………………………………………………………………………………….………………..…………….………....17

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Introduction

This following report serves to better understand the relationship between wind and wind turbines. Furthermore, it helped to determine whether a wind turbine of 77m diameter could power a housing complex of 40 houses. The purpose of the procedure, in order to answer the problem, was to understand the relationship between pressure, wind speed, and the power output and apply these relationships to a real wind turbine. The document includes the experimental methodology, the results, the discussion, the conclusion and recommendations of the team, and also individual content. The experimental methodology presents the materials used during the experiments, as well as the procedure of the experiments. The results and discussion include the data collected from the experiments presented in tables and graphs, as well as the implications of these findings. The conclusion and recommendations include the final, team agreed upon solution to the problem and how to go about solving it effectively and thoroughly. The individual content towards the end includes each team member's resolved problems regarding wind speed and pressure. Lastly, there is an appendix that includes various equations and tables referenced in the document.

Experimental Methodology

The experiment was split into two parts to accommodate for the amount of tests needed to fully understand the relationship between wind and energy.

Part One involved familiarizing the team members with the structure and function of a wind turbine. The team set up a Wind Tunnel, powered by an 18V DC Power Supply, and a Display Panel connected to the Wind Tunnel’s Fan Motor and Pitot Tube in order to analyze wind velocity data that resembles a real wind turbine. The set-up is shown below in Figure 1.

Figure 1: Experiment Set Up

When all connections, ports, and wiring were correct, the team proceeded to the next task of calibrating an Arduino Board, a part of the Display Panel. This calibration enabled the measurement of wind speeds along different radial positions of the Pitot Tube in the wind Tunnel per varying Power Inputs. The team set the DC Power Supply to 6 Volts first and recorded the wind velocities the Pitot Tube received when at

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centimeter increments starting at the edge of the tunnel and ending in the center. This process was then repeated for 9 and 12 Volt power supplies to the Fan Motor. With wind velocities recorded and plotted for each position and power input, the team also calculated and plotted the resultant pressures of each velocity using the Pressure Difference equation (Appendix: E1). Then, using the velocity data for each radial position, the average wind velocity for each voltage and its radial location in the wind tunnel was also calculated using the Average Velocity equation (Appendix: E2)

Next, at varying voltages in the Wind Tunnel based on the wind speed data collected in the previous task. To do so, the pilot tube was set at the average wind velocity radial position of 6 Volts and was used to calculate a new velocity at Power Supply Inputs of 6, 7, and 8 Volts. Repeating this process using the average radial position of 9 Volts for Power Supply Inputs of 9, 10, and 11 Volts and then using average position of 12 Volts for the 12 Volt Supply Input, the new standard velocities were recorded.

Finally, the last task of Part One used the new standard velocities recorded in the previous step to observe the relationship between the measured wind turbine power output as a function of the wind velocities. Two different wind turbines were modeled using a 2-blade propeller and a 3-blade propeller in the wind tunnel. The Display Panel was connected to the Wind Turbine Generator at the end of the Wind Tunnel in order to show the Power Output for each blade type, depicted in Figure 2 below. Changing the power input from 6 to 12 volts for the fan motor, the power output in watts of each ‘wind turbine’, 2 and 3 blade, was recorded and plotted against each other.

Figure 2: Wind Turbine Generator

Part Two of the lab was done later, after team members had time to research different Turbine Blade Geometries and create a design to be used for the experiment. The first step was for each team member to create a single turbine blade. The created blade concepts, made of balsawood, of the three team members are shown in the figures below.

Figure 3: Brooke’s Figure 4: Joshua’s Figure 5: Ian’s

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With the experiment setup of Part One, each blade design was tested at a 12 Volt Power Supply Input. The power produced from each design was recorded and compared to the other designs, and whichever design that produced the greatest power was selected to be tested further. The final step of Part Two and the experiment as a whole was testing the power produced by the selected wind turbine blade design with varying number of blades and pitch angles of those blades. First the team constructed five more blades of the selected design. Then, using a 30 degree angle, the power produced from the wind turbine generator was recorded using 2, 3, and 6 blades of the design. Finally, with whichever number of blades produced the most power, the pitch angles of 30 and 45 degrees were tested and the power produced from each was compared to determine which number of blades and at what angle creates the most power for a wind turbine. Below are figures that show some of the different configurations tested.

Figure 6: 2 blades, 30o

Figure 7: 3 blades, 45o Figure 8: 6 blades,

30o

Results

The results of the experiments are presented below.

Figure 6 below shows the relationship between the radial location and the wind velocity. The purpose of this data was to use the calculated average wind velocity using values from Table 1 to find the average wind velocity location in centimeters which was then used to calculate the area and used in later experiments. The average wind velocity locations for 6, 9, and 12 volts were determined to be 3.5, 3.02, and 3.28 cm respectively.

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Figure 6: Wind Velocities for Different Distances from the center axis of the Cylinder

Data in Table 1 was recorded using an Arduino board and wind tunnel set-up. Table 1 portrays the pressure difference at different radial locations for 6 volts, 9 volts, and 12 volts. Figure 7 displays this relationship.

Table 1: Wind Velocity vs. Radial Positon

Radius (cm) *

Wind Speed (m/s) Pressure Difference, ∆P (Pa)

r 6 volts 9 volts 12 volts 6 volts 9 volts 12 volts

0 4.80 7.40 9.00 14.8608 35.3202 52.245

1 4.90 7.50 8.80 15.48645 36.28125 49.9488

2 5.00 7.60 9.30 16.125 37.2552 55.78605

3 5.20 8.10 9.60 17.4408 42.31845 59.4432

4 5.40 8.40 9.80 18.8082 45.5112 61.9458

5 5.50 8.20 9.90 19.51125 43.3698 63.21645

The pressure difference was calculated using the Pressure Difference equation (Appendix: E1) using the wind velocities measured by the Arduino board and the density of air at standard temperature. The purpose of Figure 7 below is to display that a higher measured radius usually resulted in a higher pressure difference and a larger voltage resulted in a larger pressure difference.

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Figure 7: Pressure Difference at Different Radial Locations

Figure 8 below shows the relationship between the wind velocity and the calculated wind power produced in watts. The wind power was calculated using the Power Produced equation (Appendix: E3) using the density of air at standard temperature, the area calculated from the average radii, and the measured wind velocities. Figure 8 displays that greater wind velocities resulted in more wind power.

Figure 8: Calculated Wind Power for Different Velocities

Table 2 displays the relationship between wind velocity and wind turbine power output for experiments using a 2-blade propeller and a 3-blade propeller. The data shows the 3-blade propeller produced higher power outputs than the 2-blade propeller when supplied with the same power supply voltage. The data also shows that the power output by each blade increased as the wind velocity increased.

Table 2: Wind Turbine Power Output vs. Wind Velocity for 2 and 3 blades

Power Supply Voltage Wind Velocity From Table 3 (m/s) Wind Turbine Power Output (watts)

2 Blades 3 Blades

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6 5.35 0.007 0.004

7 6.6 0.012 0.015

8 7.5 0.016 0.020

9 7.8 0.019 0.025

10 8.6 0.022 0.030

11 9.1 0.025 0.035

12 9.8 0.029 0.040

Figure 9 displays the relationship between the power output and wind speed for a 2-blade propeller and a 3-blade propeller. The 3-blade propeller resulted in higher power outputs than the 2-blade propeller at most wind velocities.

Figure 9: Wind Turbine Output for different Propellers at various Wind Velocities

Table 3: Wind Turbine Power Output for Different Number of Turbine Blades

Design Power Output (watts)

2 Blades

.037

3 Blades

.039

9

6 Blades

.037

Three different blade designs were tested at 12 volts; the one with the highest power output was chosen to then test using 2, 3, and 6 blades. The results using the different number of blades are shown in Table 3. The data shows the power output from each design. The 3 blade design resulted in the largest power output producing 39 watts. This design was then tested at 30° and 45°, again using 12 volts. Data from Table 4 displays the results. The power output was greater at 30° which resulted in a power output of 39 watts than at 45° which produced a power output of 13 watts.

Table 4: Wind Turbine Power Output vs. Propeller Pitch

Angl e

Power Output (watts)

30o 39

45o 13

Discussion

The experiments conducted produced clear results that showed the difference between the different blade designs as well as the effect of the angling of the blades and the number of blades used. It is significant that the sharpest, thinnest blades designed were the most effective, because this is the design seen on turbines in wind farms. Another comparison to these turbines was that the most effective number of blades used, 3 blades, matches most active wind turbines today

The angle that produced the most power for the test turbine was 30°, as opposed to 45°. This was somewhat surprising, for 45° seemed like it would have provided a good balance of wind hitting both sides of the blade. After testing and seeing that the turbine performed better at 30°, it was concluded that this angle was more effective because it allowed the blade to “cut” through the air more effectively.

Another important characteristic of the data was that the relation between wind velocity and the power output of the turbine was linear. This means that the turbine works just as effectively at all wind speeds. All of these characteristics show that an effective wind turbine was found.

The experiments conducted provided fairly straightforward data, although in some ways it is hard to compare the turbines used in the experiences to actual, active turbines. This is because the turbines are made of completely different materials with different densities, and these materials may behave differently in different conditions. The turbines used in the experiment were also much smaller than actual turbines, and rotate at much faster velocities.

With regards to powering the housing complex, it was determined that the wind turbine be placed in Sandusky. This is because Sandusky and Lake Eerie in general provide high wind velocities. The average wind velocity for Sandusky was determined using Figure 10 to be 7 m/s. The wind turbine to be used to power the complex of 40 houses has a diameter of 77m. It works at 25% efficiency. Using these specifications and Power Produced equation (Appendix: E3), it was calculated that the turbine would

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produce 6181.267kWhrs/Day. The amount of energy required to power the forty houses was found using the equation below to be 2000kWhrs/Day. Based on these calculations, it is concluded that one turbine experiencing a constant wind velocity of 7m/s provide more than enough energy to power the housing complex.

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Power required for # of houses

H * Power per house

= PowerTot

40 houses * 50 kWhrs/house = 2000 kWhrs

(Number of Houses) * (Power for a single House (kWhrs/house)) = Total Power required for number of Houses

Figure 10: Ohio’s Average Wind Velocity Map

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Conclusion & Recommendation

The results of experimentation allowed the team to conclude that one wind turbine, placed in Sandusky in 7 m/s wind velocity conditions, would be able to power a housing complex of forty houses. The experiments that lead up to our being able to better understand wind energy involved designing wind turbine blades, choosing the most effective blade, and then testing it in conditions of varying wind speed. It was determined that the design presented by Figure 5 was the most effective blade design. This blade, when put onto a turbine, performed linearly with respect to wind speed (Figure 9). It was concluded that the most effective angling of the wind turbine blade was 30°, while the most effective number of blades was 3 (Table 4).

Throughout the lab procedure and recording of data, difficulties and minor implications arose that had to be dealt with to complete each task. Some of these difficulties may have had an effect on the data. One difficulty was being forced to hold the wind turbine still, which may have interfered with the wind velocity and thus output power. Other difficulties were prominently human error. From having to hand craft the wind turbine blades to making a judgment call for every wind velocity when the output was frequently fluctuating, either one of these possible sources of error could have greatly influenced the data and conclusion.

With regard to the housing complex and its power, it is recommended that a wind turbine be placed in an area of wind speed 7 m/s, such as Sandusky, Ohio. Using the Power Produced equation (Appendix: E3), it was concluded that this would provide the housing complex with 6181.267 kWhrs/Day. This is more than enough to fulfill the requirement of 2000 kWhrs/Day needed to power the forty houses. As far as the extra energy is concerned, it may be wise to either expand the housing community or else sell the energy left over.

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Individual Conclusion - Joshua Rogers

Wind Energy is increasingly growing as an energy resource across the globe. Due mostly to the part that the benefits of harnessing the wind to create a power supply are numerous. First, wind energy is a clean resource. Unlike most other types of energy harnessing/gathering, wind energy coming from wind turbines emits no emissions. The velocity of the wind exponentially relates to the amount of power generated, as shown by the power equation (Appendix: E3), and then simply leaves no trace of its involvement behind other than the motion of the turbine. Secondly, the energy that enables this use of power is completely sustainable. A natural resource, caused by the earth and solar energy, will never run out. Lastly, the advantages and application of wind energy are highly reliant upon the effectiveness of wind turbines. Wind turbines are relatively cost effective. As one of the lowest priced power generating technologies of today’s day in age, along with its capability to be placed anywhere without taking up much space, wind turbines have proven to be a huge benefit to the economy. (Advantages and Challenges of Wind Energy)

Wind energy and the wind turbines that harness the renewable, sustainable power have some drawbacks though. To start, the conversion from wind to power isn’t extremely efficient. From the background of this lab report (Lab 7: Wind Turbine Procedure), we know that at the location tested, only 25% of the power that could be generated will be. Adding to that, the locations that do have enough average wind velocity to power these turbines are normally quite rural and far away from power grids and populated areas that need the renewable energy instead of the un-sustainable kind. Lastly, the ‘conventional’ ways of generating energy compete with wind energy because the economic reward for using fossil fuels is immediate compared to wind energy that takes invested time and patience to be cost effective.

In order to fully show that each team member grasps the relationships between the different factors of wind energy, one more problem must be solved. This problem was to calculate the wind speed if the change in pressure measured by the Pitot tube is 100Pa and the density of air at that time was 1.29 kg/m3. The problem was solved following the steps below. First, a version of Bernoulli’s Equation was rearranged to solve for the velocity, and then last, the known variables were inputted to find the value.

The calculated wind speed was found to be 12.45 m/s if the change in pressure was 100 Pascal and the

density of air was 1.29 kg/ m3

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2.v2=√ (2∗∆ P)

ρ(air)

3.

v2=√ (2∗100 Pa)

1.29 kg /m3

1.∆ P= ρ(air)∗v2

2

2 4. v2 = 12.45

m/s

Individual Conclusion - Ian Campbell

1. Wind energy is an important source of energy for many reasons. It can also be difficult to apply, for there are also disadvantages. One advantage of wind energy is that it is a sustainable resource. This is because wind is renewable, and the only thing needed to generate the turbines is wind. There is also a disadvantage that is in the same vein, for the turbines only work in areas of high wind. This puts a restriction on where you can use wind turbines. Another advantage of using wind energy is that after the initial cost of setting up the turbines, there is little to no extra cost to get the energy. This is both an advantage and a disadvantage. An advantage because in the long run, there will be money saved. It is a disadvantage because the costs in the short term are very high. One last advantage of using wind energy is that wind turbines can be placed almost anywhere, including off shore. This is beneficial because they can be placed on agricultural land, which would conserve space. The disadvantage to this is that this may not be the most efficient way use the land. Overall, wind energy’s advantages outweigh its disadvantages.

2. Using equation E1:

Change in Pressure (Pa)=density of air (kg/m^3) * wind velocity^2 (m/s) * (1/2)

Solving for wind velocity, I multiply each side by 2 and divide by the density to get

Wind velocity^2 (m/s)=2(Change in pressure (Pa))/(Density of air (kg/m^3))

So,

Wind velocity (m/s)=sqrt(2(Change in pressure (Pa))/(Density of air (kg/m^3)))

=sqrt(2(100/1.29))

=12.45 m/s

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Individual Conclusion - Brooke Robinson

The importance of wind energy is growing daily; however, there are advantages and disadvantages. Advantages of wind energy include that it is a clean, renewable energy source and can be converted to electrical energy. 1 Another advantage of wind energy is that it is cost effective. 1 The field of wind energy is growing and expanding, and new technology has greatly decreased the cost of wind energy and wind turbines since they were first used. However some disadvantages of wind energy are that fossil fuels are still usually cheaper, locations of wind farms might be far from where the electricity is needed and the electricity will then need to be transmitted, and wind farms might not be the most cost-effective use of the land. 1 While wind energy is cost effective and researchers are continuously looking for ways to make it cheaper and more practical, it still might not be the most cost effective use of the land in certain areas.

A change in pressure of 100Pa with the density of air at that time to be 1.29 kg/m3 would result in a wind speed of 12.45 m/s.

velocity=√ 2∗∆ P ρ

12.45 m /s=√ 2∗100 Pa 1.29 kg /m3

Sandusky, Ohio’s annual average wind speed at 80m is approximately 7m/s. At this wind speed and the dimensions of a turbine with a 77m diameter, 25% efficiency, blades 32m long and turbine height of 80 m the power it would produce is 6181.27 KWH per day. This is more than enough to power the residential complex with 40 houses that require 50 KWH/Day per house. The entire residential housing complex would need 2000 KWH/Day and our calculations support that a wind turbine with these dimensions in Sandusky, OH would be able to produce enough power to power the entire complex. This location is near a lake; therefore, receives higher wind speed than other places located on the map in Ohio and is a reasonable location for wind turbines.

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References

"Watts to KWh Calculator." Rapid Tables. RapidTables.com, 2014. Web. 11 Nov. 2015.

“Wind Turbine Design.” Wikipedia, Wikimedia Foundation, 22 Oct. 2015. Web.

"Lab 7: Wind Turbine Procedure." The Ohio State University College of Engineering, n.d. Web. 11 Nov. 2015. PDF.

"Advantages and Challenges of Wind Energy." Energy.gov. US Department of Energy, n.d. Web. 11 Nov. 2015.

“Advantages And Challenges.” http://energy.gov/eere/wind/advantages-and-challenges-wind-energy

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Pressure difference (Pa) = density of air (kg/m3) * wind velocity2 (m/s) / 2

Average Velocity (m/s) = (2 * Total Wind Power (watts) / area (m2) * density of air (kg/m3))1/3

Power (watts) = ½ * density of air (kg/m3) * area (m2) * velocity3 (m/s)

Flow rate, Q (m3/s) = velocity (m/s) * area (m2)

Mass flow rate (g/s} = density of air (kg/m3) * flow rate, Q (m3/s)

(E1)

(E2)

(E3)

(E4)

(E5)

Appendix

Equations and Sample Calculations

Pressure Difference ∆ P= ρ(air)∗v2

2

2

14.86 Pa=

1.29 kg m3∗4.80(

m s )

2

2

Average Velocity vaverage=( 2 P A ρ )

1 /3

5.31 m/ s=( 2∗.918 watts

.009503 m2 ∗1.29

kg

m3 ) 1/3

Power Produced P= 1 2

ρA v3

.9386 watts= 1 2 ∗1.29

kg m3∗.0095 m2

∗5.35( m s )

3

Volumetric flow rate, Q Q=vA

.0508 m3

s =5.35(

m s )

3

∗.0095 m2

Mass flow rate, m-dot m=ρQ

.0656 kg s

=1.29 kg m3∗.0508

m3

s

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