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Name ______________________

Wind Power

1. The essential components of almost every power generation system are _____________and ________________

2. A coal-fired power plant uses ____________ to turn a ________________

3. The three components of every wind turbine are the _______________,________________, and __________________

4. In general, is it better to have strong wind half the time, or medium wind all the time?Explain your considerations.

5. List three pros and three cons of wind energy:

6. Given V=IR (Ohm's Law) and P=VI (power equation), derive the power equation as afunction of voltage and resistance.

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7. Wind turbine blade brainstorm (you can draw ideas sideways):

Idea 1:

Idea 2:

Idea 3:

Idea 4:

Idea 5:

Develop 5 different design selection considerations, and then score your ideas with a +, -,

or 0. Circle your best scoring idea.

1 2 3 4 5

Total

Blade Design Consideration

Ideas

Selection Matrix

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Wind Turbine Optimization Worksheet

In order to customize our wind turbine for the given wind conditions, it is necessary to

choose a blade arrangement that maximizes generator power output. This part of the engineeringdesign process is known as refinement or optimization.

Step 1) Choose a blade configuration

You should have at least six blades in your turbine blade set. Start testing your turbine with six

blades. Take voltage and current data for the six-bladed configuration then begin to

remove/rearrange blades and take more data for the following configurations:

Blade Configuation Voltage (volts) Resistance (Ohms) Power (miliwatts)

6 Blades

4 Blades

3 Blades

2 Blades

Other?

Other?

Wind Turbine Blade Configuration Optimization Data

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Please create a graph of your results in the space provided

below:

Which blade configuration produced the most power?

Why do you believe this blade configuration produced the most power?

From these data, please decide on a blade configuration. You do not need to choose the blade

configuration that produced the maximum power. Please explain the reason(s) for your choice

below:

Step 2) Choose a blade angle

In order to truly optimize our wind turbines, we must not only choose the appropriate number of

blades, but also the blade angle, sometimes called the angle of attack that maximizes power

output.

In order to adjust the angle of your blades, use the handy-dandy protractor on the back of this

worksheet. Line up the 0 degree line of the protractor with the edge of your wooden base, then

line up the turbine blade with the appropriate angle mark. Record voltage and current

measurements for the following angles:

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Note: please let other students use the fans while you are adjusting your blade angles

Blade Angle Voltage (volts) Resistance (Ohms) Power (miliwatts)90 (cutting the wind)

67.5

45

22.5

0 (flat)

Other?

Other?

Other?

Wind Turbine Blade Configuration Optimization Data

Please create a graph of your results in the space provided

below:

Which blade angle produced the most power? Why do you think this happened?

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Which blade angle would you choose for your wind turbine? Why?

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Step 3) Calculate the efficiency of the wind turbine

As an engineer, it is important not only to optimize your system, but to understand how your

optimized system holds up against the ideal. The comparison of your systems performance to

the ideal is called efficiency and is symbolized with the Greek letter eta:

=Pactual/Pideal For a wind turbine, the ideal power is Pideal= (1/2)r2v

3

Where is the density of the air, r is the radius of the turbine, and v is the velocity of the wind.

The density of air in Colorado is approximately 1 kilogram per meter cubed, the radius of the

turbine can be measured with a ruler/tape measure (in meters!), and the velocity of the wind can

be measured with the blue wind meter (in m/s!).

Density of air = ___________kg/m3

Radius of turbine =___________m

Velocity of the wind=_____________m/s

Pideal= (1/2)r2v

3=______________watts

Now you know the ideal or maximum power output of the most perfect turbine

someone could ever build. This turbine would suck 100% of the winds kinetic energy out of the

air. We want to compare our turbines to the ideal uber-turbine. Find your maximum measured

power output (optimum number of blades with optimum angle) and write it below. Be sure to

convert it to watts (it is currently in milliwatts so you need to divide your previous value by 1000

to get the power in watts).

Pactual=____________watts

Now, calculate the efficiency of your turbine by dividing you power value by the ideal value. Be

sure to convert your answer to percent by moving the decimal place to the right by two places.

=Pactual/Pideal=____________%

Wow, that is low! Please provide three ideas as to why our turbines efficiencies are so low:

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Extra Challenge:

Rather than choosing an optimum blade angle from a limited set of tested angles, fit your data

with a fourth-order polynomial. Use either Excel or a graphing calculator to accomplish this.Once you have your fourth-order polynomial equation, write it here:

___________________________

Now, use calculus or observation to determine where the first derivative of the polynomial is

equal to zero (the slope of the line is zero). This indicates a location where the curve is at a

maximum (ie the slope of the curve is zero). If you are uncomfortable to calculus, or just dont

feel like doing it, you can just eyeball where the curve is a maximum. It is at this location that

the power output of the blades should be (roughly) maximum.

Extra-Super Challenge:

A loop of wire with cross-sectional area A is rotating within a homogeneous magnetic field of

field strength B. As the wire loop turns, the amount of magnetic field, B, entering the loop is

reduced and increased in accordance with angle of the wire with rotational velocity . As the

magnetic flux within the wire loop changes, a voltage is produced in accordance with the

following differential equation:

V=d/dt where d represents rate change of the magnetic flux

and t represents rate change of time.

Using trigonometry, geometry, Ohms law, and basic calculus, calculate the equation for current

through the external load resistor, R.

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Handy-Dandy Protractor

0

22.5

45

67.5

90

67.5

45

22 5

0

Towards Fan

Windturbinehub