The Effect Of Wind Direction On Wind Turbines

I expected to learn from this project what the effect wind source direction had on a horizontal wind turbine. I found out that going from one side to the other, depending on how the pinwheel was shaped, that the power generated would increase or decrease. The homemade pinwheel generated power that peaked at the 180 degree mark and gradually went down with a slight spike upwards at the 0 degree mark. The store bought pinwheel had an average power that peaked at 180 degrees and went down gradually and spiked all the way almost to the 180 degree mark at 0 degrees. These results are important because currently, there are wind farms and they have windmills to produce energy, it is important to imply these facts when constructing the windmill to know how to make the windmill most efficient to produce the most energy it can with the given situations.

Background Research

Introduction

My project researches wind turbines and how changes in wind direction affect the amount of work the windmill can do. I will use two types of turbines – a store-bought pinwheel and a homemade pinwheel. The two turbines will be exposed to the same amount of wind force and wind source direction. As I change the angle that the wind blows, I will calculate the amount of energy it takes to do the same task – haul five paperclips vertically.

My project question is: What effect does wind source direction have on a horizontal wind turbine?

My hypothesis is: The more indirect the wind source is, the slower the turbine will spin, thereby working harder and using more energy.

For many years my family and I have been going to Lake Tahoe. Every time we travel there, we pass a field of windmills. I used to always ask my dad what they were for and how they worked. I always loved to watch them spinning. When I was looking for a science fair topic, I saw an experiment involving wind turbines. I remembered the windmills on the way to Tahoe and thought it would be interesting to find out how they really work. I thought the mechanics of this project would be fun to make and to watch work. I hope to learn how wind turbines generate electricity, the mechanics of windmills, and under what conditions windmills spin the fastest.

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Scientific Background

When it comes to windmills or wind turbines, there are two major types. The more well known type is the Horizontal Axis Wind Turbine (HAWT). These wind turbines are the ones you typically see; they are your stereotypical type of windmill. The other type is known as the Vertical Axis Wind Turbine (VAWT). These wind turbines are not as common but still have the same capability of the HAWTs. The VAWTs are not used as much because they puts more strain on the support pole, making them more likely to collapse. They also need a small generator to start spinning because most of the time the wind is not strong enough to push it alone. These windmills have generators inside of them that generate electricity when the gears spin.

Discovery

The first windmill was invented by none other than the Heron of Alexandria, in Greece, in the first century AD. He invented this “windwheel” to power a musical organ; however, this idea of wind power was not well embraced. At the time, slave labor was cheaper, faster, and more reliable. The first modern designed windmills were invented by the Persians in the 9th century AD. There is no one inventor to which to give the credit, but Persian geographer Estakhri noted the invention.

The discovery of wind power is important because it introduced a new, free source of energy other than slave labor. Today our environment is at risk of being destroyed. Due to the increase in population and technological advances, the resources in our world are quickly being depleted and we are damaging our environment. We are using an increased amount of energy, specifically fossil fuels, to power almost everything we use. Instead of using fossil fuels we could and should be using more wind energy to create energy.

Despite these masterminds of history, there is still more to be discovered in this area. Scientists could discover a new, more reliable, and more efficient model of wind turbine to replace the HAWTs. They need to discover more in this field in order to replace fossil fuels and stop global warming.

Application

Today, we use windmills as a renewable source of energy and electricity. If scientists in the future can have a breakthrough with windmills, it could permanently replace fossil fuels, therefore stopping global warming. Residential wind power is becoming more available, but not as accessible as we need them to be.

Conclusion

From this project, I hope to learn how wind turbines generate energy. I hope to learn some of the mechanics behind windmills, under what conditions windmills spin the fastest, and how they can create energy.

Experiment Details

Experiment Question

What effect does wind source direction have on a horizontal wind turbine?

Experiment Hypothesis

The more I move the wind source to one side of the turbine, the wind turbine will spin more slowly.

Experiment Variables

Independent Variable

The angle in degrees that the wind source will blow at the rotor.

Dependent Variable

How much time, in seconds, it will take the wind turbine to pull up 5 paperclips.

Controlled Variables

The amount of weight the wind turbine will pull up

The amount of wind being blown at the wind turbine (hairdryer on high speed)

The temperature of the air being blown (hairdryer on cool setting)

The height the turbine will have to life the paperclips

The wind turbine itself

Materials and Procedures

Materials Used

Pinwheel, store-bought or homemade

Scissors

8.5-inch x 8.5-inch sheet of paper

Ruler

Pen

Nail

Wooden skewer, available at grocery stores

Tape, any kind

Empty oatmeal canister with plastic lid

Handful of rocks (or heavy objects to keep the oatmeal canister weighted down)

Small compression spring (approximately ½ inch long and able to fit over skewer)

Clear tape

Spool of thread (1)

Paper clips, #1 size (5)

Measuring tape

Room in your home that is free from drafts

Hair dryer

Table or chair

Sticky notes, small size

A helper

Stopwatch

Lab notebook

Graph paper

Procedures

Building My Rotor

For a store-bought pinwheel:

STEP 1: I have to remove the rotor blades from the shaft by cutting off the plastic nozzle tip of the shaft. This rotor is now on the skewer and is ready for testing.

For a home-made pinwheel:

STEP 2: Fold a square piece of paper diagonal then back then diagonal the other direction then back. When I am finished I should have an “X” crossing the middle of my paper.

STEP 3: Measure about 2 inches from the center on each crease and draw a line with my pen.

STEP 4: Make four holes in the paper with the nail near the corner.

STEP 5: Make a fifth hole in the center of the paper

STEP 6: Cut along the creases with the scissors and stop where the lines were drawn 2 inches out from the center.

Building my Horizontal-Axis Wind Turbine

STEP 7: Use the nail to poke two small holes on corresponding sides of the Oatmeal container about one inch down from the top.

STEP 8: Place rocks inside the container and close the lid.

STEP 9: Put the skewer between the two holes.

STEP 10: Thread the spring on one side of the skewer.

STEP 11: Put on one of the rotors (homemade or store bought) next to the spring on

the skewer.

STEP 12: If I were using the homemade rotor I must first fold the four corner

holes onto the middle hole so they are all on top of each other and form

one hole. Then thread the skewer through the hole and the rotor is ready.

STEP 13: Tape the rotor to the skewer so it will not slip off the skewer.

STEP 14: Cut about 2 feet of thread.

STEP 15: Tie one end of the thread to the end of the skewer that does not have the

rotor taped to it.

STEP 16: Tie the other end to one paper clip. Then attach the remaining four paper

clips to each other then attach the four to the first one that is tied to the thread. This is the load that the wind turbine will be pulling.

STEP 17: Measure the threads full length with the measuring tape from the skewer to

the first paper clip. Record measurement in lab notebook. Now I am ready

to start testing.

Testing My Wind Turbine

STEP 18: Place Wind turbine on the edge of a table or chair in a room without drafts.

STEP 19: I will be testing my wind turbine at five different points around the rotor, 0

degrees, 45 degrees, 90 degrees, 135 degrees, and 180 degrees. To mark

these points on the table, extend and lock the measuring tape so that it is

approximately 6 inches longer than the radius of the rotor. Hold one end of

the measuring tape directly below the point where the rotor meets the

skewer, and the other end of the measuring tape at the approximate points

around the pinwheel. Mark the points on the table with small sticky notes. When I begin the test, I will hold the handle of the hair dryer on the sticky notes and the blower end will point at the rotor. The goal is to have 1-2 inches between the rotor and the blower. If I don’t have enough room, or have too much space, then I would have to adjust my sticky notes outward or inward.

STEP 20: Have the helper manage the stop watch while you hold the hair dryer in

position. As a test run, start the hair dryer on low and move it from sticky note to sticky note and record what happens in the notebook.

STEP 21: Extend thread to full length

STEP 22: Place the handle of the hair dryer on the first sticky note and turn the hair

dryer on low and face it away from the rotor.

STEP 23: When the helper says go, point the hair dryer at the rotor and leave it there.

Keep the hair dryer at the same level for every test.

STEP 24: Observe the motion of the paper clips. When the top of the first paperclip

reaches the skewer, the helper should stop the stopwatch. If the paper clips do not to rise all the way to the skewer, then stop the stopwatch when the paper clips stop moving.

STEP 25: Turn off the hair dryer when the clips reach the top or when they stop

moving and record the time in the table drawn in the notebook.

STEP 26: Repeat steps 21-25 until all testing is done.

Challenges and Technical Issues

I experienced several technical challenges relating to timing and angle as I performed this experiment.

First, it was difficult to keep the direction of the air source constant. While I held the hairdryer, I found it difficult to keep it still. It was also difficult to ensure that the angle was kept constant throughout the experiment. I did my best to make several markings on the table to align the hairdryer.

I also found that while using the homemade pinwheel, the pinwheel would sometimes push the skewer forward, causing the string to make contact with the canister, therefore slowing it down. To resolve this, I moved the pinwheel to the front end of the skewer and secured it there.

Similarly, I found that while using either pinwheel, the string would sometimes wrap part of the way on the skewer but run out of skewer and fall off the edge before it was fully wound. To resolve this, I moved the string closer to the canister so there was more room for it to wind onto.

Timing was also one of the human errors. Coordinating the actual start and stop of the stopwatch with the actual wind source (hairdryer) was tricky. My assistant and I counted down 3-2-1 and got as close as possible. There were times that we needed to restart the trial due to timing issues.

Experiment Results

With my tests results from the store bought pinwheel, the averages in ascending order staring at zero degrees going up are: 27.18 seconds, 36.94 seconds, 47.84 seconds, and 26.53 seconds. In these tests, there was only one outlier. That outlier was in the 90 degree testing when the outlier was below every other time with a time of 28.36 seconds. This was due probably to movement of the wind angle.

In the homemade pinwheel, the averages of the times are in ascending order from zero degrees going up are: 57.86 seconds, 1 minute 2.20 seconds, 1 minute 21.66 seconds, 41.67 seconds, and 35.11 seconds. There were four outliers within these tests. One was with the 0 degrees test; it had a time of 1 minute 7.97 seconds. There were two outliers in the 45 degree angle testing. The first had a time of 40 seconds and the next had a time of 1 minute 12.17 seconds. Both of these did not get all the way to the top of the canister. The fourth outlier was in the 135 degree tests with a time of 1 minute 4.91 seconds. All of these faulty times were most likely due to movement of the hairdryer.

With all of the outliers in my experiment, I included them into the average and did not change or discard them.

Time Data Table

Store-Bought Pinwheel

Position of Wind Source (degrees)

Time to Raise Load

(seconds)

Trial 1

Trial 2

Trial 3

Trial 4

Trial 5

Average

Uncertainty

0

29.78

31.81

23.85

26.90

23.54

27.18

Range: 8.27 sec.

Human error possibility: movement

45

38.62

38.87

43.38

33.56

29.78

36.84

Range: 13.6 sec.

Human error possibility: movement

90

38.75

36.61

42.22

38.74

28.36

36.94

Range: 13.86 sec.

Human error possibility: movement

135

45.41

54.28

49.75

47.82

41.93

47.84

Range: 12.35 sec.

Human error possibility: movement

180

28.10

25.98

28.88

27.31

22.38

26.53

Range: 6.5 sec.

Human error possibility: movement

Time Data Table

Home-Made Pinwheel

Position of Wind Source (degrees)

Time to Raise Load

(seconds)

Trial 1

Trial 2

Trial 3

Trial 4

Trial 5

Average

Uncertainty

0

53.91

54.34

1:07.97

54.66

58.44

57.86

Range: 14.06 sec.

Human error possibility: movement

45

40.0

1:12.17

56.06

1:07.59

1:15.18

1:02.20

Range: 35.18 sec.

Human error possibility: movement

90

1:30.43

1:29.16

1:04.91

1:23.35

1:20.43

1:21.66

Range: 25.52 sec.

Human error possibility: movement

135

45.78

41.59

44.94

39.53

36.50

41.67

Range: 9.28 sec.

Human error possibility: movement

180

35.22

37.56

37.31

32.38

33.09

35.11

Range: 5.18 sec.

Human error possibility: movement

Distance-Work Data Table

Store-Bought Pinwheel

Average Work Done = Force . Average Distance (N . m )

Mass of load (5 paperclips) = 0.00215 kg

Force = Mass x 9.81(m/sec2) = 0.0210915 Newtons

Position of Wind Source (degrees)

Distance Paper Clips Were Raised

(cm)

Trial 1

Trial 2

Trial 3

Trial 4

Trial 5

Average Distance

(meters)

Average Work Done

(N . m )

0

61

61

61

61

61

0.61

0.013

45

61

61

61

61

61

0.61

0.013

90

61

61

61

61

61

0.61

0.013

135

61

61

61

61

61

0.61

0.013

180

61

61

61

61

61

0.61

0.013

Position vs. Power Data Table

Store-Bought Pinwheel

Position of Wind Source (degrees)

Power=Average Work Done Divided By Average Time (W)

0

.0004782

45

.0003528

90

.0003519

135

.0002717

180

.00049

Distance-Work Data Table

Home-Made Pinwheel

Average Work Done = Force . Average Distance (N . m )

Mass of load (5 paperclips) = 0.00215 kg

Force = Mass x 9.81(m/sec2) = 0.0210915 Newtons

Position of Wind Source (degrees)

Distance Paper Clips Were Raised

(cm)

Trial 1

Trial 2

Trial 3

Trial 4

Trial 5

Average Distance

(meters)

Average Work Done

(N . m )

0

61

61

61

61

61

0.61

0.013

45

16.5

38

61

61

61

0.475

0.010

90

61

61

61

61

61

0.61

0.013

135

61

61

61

61

61

0.61

0.013

180

61

61

61

61

61

0.61

0.013

Position vs. Power Data Table

Store-Bought Pinwheel

Position of Wind Source (degrees)

Power=Average Work Done Divided By Average Time (W)

0

.0002246

45

.0001607

90

.0001591

135

.0003119

180

.0003702

Data Analysis and Discussion

There is one main reason why I got the results I did from my experiments. I got these results because of the way the pinwheel is shaped to spin. For example, the home made pinwheel I shaped, not intentionally, to spin to the right and it had fewer blades than the store bought pinwheel, but the store bought pinwheel was manufactured to spin to the left. In addition, the store bought pinwheel had twice as many blades as the homemade pinwheel; therefore it was able to catch more wind from the hairdryer, making the averages of the store bought much higher than most of the home made pinwheel averages.

Windmills, when they spin, produce energy via a generator. The windmills I constructed are the same way but without a generator. I was able to calculate the power the windmills generated by pulling up the five paperclips and by using the time they needed to pull the paperclips all the way to the top. My graph shows the power that was generated using the load pulled (2g) and the time needed to pull the load on a scatter plot graph. The line that is drawn between the points is the trend in increase or decrease of the data. On the x axis, the position of the wind source in degrees is shown. On the y axis, the power in watts that is being generated by the windmill pulling the paper clips. This graph is useful to me because it is an easy way to show which position and windmill produced more power.

My results answer my original question with proof from the experiments; it shows that my hypothesis was incorrect. Regarding the store bought pinwheel, the power in watts goes down starting from 0 degrees but then spikes up at 180 degrees. The home made pinwheel goes down all the starting from 180 degrees to 0 degrees. I never stated in my hypothesis that it mattered which direction, whether left or right, it decreased from.

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Conclusion

My hypothesis was incorrect.

I thought the more I moved the wind source from the center to one side of the turbine, the wind turbine would spin more slowly and produce less power. I expected the graph to show an upside down “V”. This was disproved with my trials. The trend line essentially formed a “V”, showing an increase in power produced with both pinwheels.

Recommendations

If someone does want to retry this project or study more in this field, I would give them the following advice.

If someone wanted to retry this experiment, I would recommend that they try to eliminate all possible human and mechanical errors such as movement. They could try to make a stand for the hair dryer to ensure that it stays straight and at the same height for each test. Slight movements can make a difference in how the wind catches the blades of the pinwheel.

For someone wanting to study in this field, I would recommend that they perform this experiment comparing pinwheels that were equally matched. That is, use pinwheels that have the same number of blades in the same direction. They could also test pinwheels made of different materials and compare them that way.

If someone just wanted to know which pinwheel to buy to be most efficient, I would tell them to get one that is made out of sturdy material, has a lot of blades, and one that has blades that are perfectly shaped to catch the wind.

Acknowledgements

For this experiment, there are a few people that I would like to mention who helped me perform this experiment. First, this project took me about three hours in all to perform and many after that to organize the board and all of the data. Throughout those hours, my mother helped motivate me to get my project done, helped me perform my experiment. She gave me the knowledge of how to make a computerized graph and helped me when I struggled. I would also like to mention Mrs. Roy, my 8th grade science teacher, for giving me initial tips on what to do differently with my experiment to make it the best it could be.