A Wind Turbine can be used to change wind power into electrical power. We will be looking at the Science behind how generators work in a later unit, but the Math behind this  is quite complicated, as you can see:
                                

P = 0.5 x rho x A x Cp x V^3(cubed) x Ng x Nb
● P = power in watts (746 watts = 1 hp) (1,000 watts = 1 kilowatt)
● rho = air density (about 1.225 kg/m3 at sea level, less higher up)
● A = rotor swept area, exposed to the wind (m2)
● Cp = Coefficient of performance (.59 (Betz limit) is the maximum theoretically possible, .35 for a good design)
● V = wind speed in meters/sec (20 mph = 9 m/s)
● Ng = generator efficiency (50% for car alternator, 80% or possibly more for a permanent magnet generator
or grid-connected induction generator)
● Nb = gearbox/bearings efficiency (depends, could be as high as 95% if good)

To make our investigation simpler, we will skip the complicated bit and instead determine the power by measuring how long it takes the wind turbine to wind up a piece of string.

Your task:

Write a plan on a google doc for investigating how one aspect of the blade design could affect the speed at which the turbine turns. 

Have a look at this website which shows you one way to create a wind turbine model.

Here is a list of what you need to include in a plan again:

• Research Question - A question you want to find an answer for through your experiment
• The variables - you can find out what these are here.
• Prediction/Hypothesis - try and make a guess as to what you think will happen, with reasons.
• Materials list - a list of materials that you need for the experiment.
• Method - a step-by-step guide to how the experiment will be done.

When you are ready. Email Ms Lai at flai@ichk.edu.hk to get your plan approved. Also ask them if they have your materials. While you are waiting for a reply, you can look up some videos on wind turbines in different countries, write some notes in your google doc.

A note about your independent variable (which is your one aspect of blade design):
There are so many possible variables, but we would like you to focus on:
● Blade Design : without blades, your turbine wouldn’t produce any electricity.
● Some factors to consider: Size, Shape, Number, Material
Remember: when you change one variable, you must keep all other variables constant.

Gather your materials and make it! You may need to make more than one set of blades for your independent variable.

You are now ready to investigate the independent variable you picked! You may want to do it more than once to ensure that your results are reliable.

When you are doing the experiments, take some photos and put them under "Observations and Results" on your google doc. Do write that any observations you make throughout the experiment too.

Put any figures or numbers into a table form.