Introduction to Wind Turbines

Students have probably seen huge wind turbines spaced out in open land. Some may have even asked their parents what wind turbines are for and were probably given a quick answer like: they are used to provide electricity for homes

But how does exactly does it work? Why are they always found in open areas? The goal in this demonstration is to help students understand the conversion of kinetic energy into mechanical power.

The method of using wind to harness energy can be tracked as far as 5,000 BC as they were used by Persians as a source of rotational energy to help grind grains. Other uses of wind turbines include sawing of lumber, producing electricity and many others. In this demonstration, we will talk about how Wind turbines can generate electricity for our homes. More specifically, we will show that the power being produced from wind turbines are proportionally to wind velocity cubed.

Above, we have a simple diagram of the basic parts that make up a wind turbine. As we can see in this diagram, we have the Blade, which is attached to a motor, a pole, and a base that holds everything up.

Now, if we take a look at this turbine that I have constructed above, you can see that there are a few extra parts I am missing here. Real turbines have a tail which detects the direction of wind and in compliment to that there is also what we call a Yawing System that rotates rotor to face the wind direction

Another to take note about is that in Wind farms, where groups of wind turbines are placed on an open land, spacing of wind turbines is very crucial. If turbines are placed too close together, it will cause turbulence in wind, which in return will cause stress on the motor. As a result, reducing the lifespan of rotors.

Wind farms often use what is called a 5 rotor diameter square grid system. As its name suggests, turbines are placed 5 rotor diameter apart to maximize the efficiency of wind turbines.

The figure above shows a general overview of the energy production process.

1) We have a turbine that is placed in location with as little obstruction as possible with wind blowing directly into the turbine, causing the blades to spin.

2) The spinning blades attached to a rotor spins a series of gears to produce electricity.

3) Once the electrical current is produced, it flows down to a step-up transformer where electricity is converted to higher voltages to account for power being loss in the resistance of transmission lines.

Design/Construction

To construct a mini wind turbine, you will need:

- Fan (as wind source)

- Helicopter propellers (as wind turbine blades)

- Small direct current motor

- Plastic tube (tower support)

- 2 electrical wires

- voltmeter

- ammeter

- anemometer

- resistant variables

Above shows a visual of how this demonstration will be set up. The fan will be placed directly facing the wind turbine.

To construct a wind turbine, attached the propeller onto the motor with a plastic knob. The motor should be held standing with a plastic tube. Use one electrical wire to connect the rotor to the voltmeter and another to connect to the ammeter. Set the voltmeter to read in millivolts and ammeter to read in micro amps.

In order to measure the power being produce, simply multiply the readings from the voltmeter and ammeter. Note that your power will be in Nano Watts.

To demonstrate the dependence of wind velocity on power being produced, an anemometer is used to measure the wind speed. To increase the wind speed, simply shift the fan closer to wind turbine. However, when adjusting the wind speed, a resistor variable will need to be changed each time to get the highest voltage and current reading. Consult the diagram below to see how electrical wires should be attached:

Presentation

The Power being produced by wind turbine depends on 3 variables:

1) Density of air, which we know is 1.225kg/m^3

2) Area being swept by blades, which we will calculate from measuring the radius of the blades we have using pi*r^2

3) Wind speed

In our demonstration we will be looking at the power being produced with changes to wind speed.

Power being produced by wind turbine is given by the following equation:

P = 0.5 * rho *A*V³*C_p

From this equation, we can see that power being produced is proportional to velocity cubed:

P_wind propotional to V³_wind

So when we take measurements and plot power against velocity of wind, we should be aiming for a Cubic curve.

PowerPoint Presentation: You may find these PowerPoint presentation useful: https://1drv.ms/p/s!AlqYVGMWcFVViWIZuxkEhRL6LkY8

Video Demonstration: You may this short video helpful: https://1drv.ms/v/s!AlqYVGMWcFVViWSc_-ycTnffsv4L

Excel for Simple Plotting:

Below is an example of how you can preset your excel file so that during the presentation, you can easily enter in the numbers and the plot will show appear as below. The final curve of your plot should be a cubic curve as the power being produced is proportional to wind velocity cubed.

Bibliography

Danau, Andy. “How Wind Turbines Generate Electricity” 08 September 2009, https://www.youtube.com/watch?v=0Kx3qj_oRCc. Accessed 17 September 2016.

Kelly, John. “How Stuff Works Science.” 5 Ideas for Experiments on Conserving Energy, 16 April 2012, http://science.howstuffworks.com/environmental/conservation/conservationists/5-experiments-conserving-energy5.htm. Accessed 17 September 2016.

Laino, David. “Home Power.” Wind Energy Physics, July 2014, http://www.homepower.com/articles/wind-power/design-installation/wind-energy-physics. Accessed 18 September 2016.

Sheppard, Alyson. “Popular Mechanics.” Make Your Own Miniature Wind Turbine, 26 April, 2013, http://www.popularmechanics.com/science/environment/how-to/g118/make-your-own-miniature-wind-turbine/. Accessed 17 September 2016.

Snurr, Randall. “Energy Fundamentals.” Physics of Wind Turbine, 01 May 2015, http://www.energy-fundamentals.eu/15.htm. Accessed 17 September 2016.

Statistics Canada. “Electrical generating Capacity”. Statistics Canada catalogue No. 11-402-X, 27 November 2015. http://www.statcan.gc.ca/pub/11-402-x/2012000/chap/ener/ener01-eng.htm. Accessed 18 September 2016.