Hands-on Science and
Engineering at Pasadena
Public Library
May 19, 2017

Energy cannot be created or
destroyed; it can only be converted
from one form to another.

“In the case of a wind-electric turbine,
the turbine blades are designed to
capture the kinetic energy in wind. The
rest is nearly identical to a hydroelectric
setup: When the turbine blades capture
wind energy and start moving, they spin a
shaft that leads from the hub of the rotor
to a generator. The generator turns that
rotational energy into electricity. At its
essence, generating electricity from the
wind is all about transferring energy from
one medium to another.”
http://science.howstuffworks.com/enviro
nmental/green-science/wind-power.htm

You will want your blades to move as fast as
possible without creating too much air
turbulence, because more revolutions per
minute (RPM) means more energy.
https://www.slideshare.net/jayharris21852/potential-and-kinetic-
energy-power-point-and-audio
http://msclantonsphysicalsciencepage.weebly.com/a-
formula-for-kinetic-energy.html

As the windings are energized, they attract to the magnets located around the
motor. This rotates the motor until the brushes make contact with a new set of
commutator contacts. This new contact energizes a new set of windings and
starts the process again. To reverse the direction of the motor, simply reverse
the polarity on the motor contacts. Sparks inside a brush motor are produced
by the brush jumping to the next contact. Each wire of a coil is connected to
the two closest commutator contacts.
https://learn.sparkfun.com/tutorials/motors-and-selecting-the-right-one

*Windpumps were first used by
Muslims in the Middle East and
Central Asia in the 9th century
*The first known instance of using
wind to power a machine was by the
Greek inventor Hero of Alexandria in
the 1st century? He invented a wind
powered organ with a wind wheel
that powered a piston and forced air
into pipes (see upper left).
*Dutch windmills were not only about
making flour. Many windmills also
pumped water out of the ground,
which was necessary because most
of the Netherlands is below sea
level.

p. 17, Wind
Power by Ian
Graham,
published by
Raintree
Steck-
Vaughn
Publishers

To understand that, you need to
see what the wind looks like
hitting sails that DON’T have slots:
http://www.johnhearfield.com/Wind/Windmills.htm

When the air is allowed to flow both through
the wing and around it, the wing is more
likely to move.
Just like a fly swatter!
http://www.johnhearfield.com/Wind/Windmills.htm

“In drag-based wind turbines,
the force of the wind pushes
against a surface, like an open
sail. In fact, the earliest wind
turbines, dating back to ancient
Persia, used this approach. The
Savonius rotor is a simple drag-
based windmill that you can
make at home (Figure 1). It
works because the drag of the
open, or concave, face of the
cylinder is greater than the drag
on the closed or convex
section.”
http://people.bu.edu/dew11/lif
tanddrag.html

“This requires specially shaped airfoil
surfaces, like those used on airplane
wings (Figure 2). The airfoil shape is
designed to create a differential
pressure between the upper and lower
surfaces, leading to a net force in the
direction perpendicular to the wind
direction. Rotors of this type must be
carefully oriented (the orientation is
referred to as the rotor pitch), to
maintain their ability to harness the
power of the wind as wind speed
changes.”
http://people.bu.edu/dew11/liftanddr
ag.html

http://www.pfr.co.uk/pfr/3/Renewable-Energy/15/Wind-Power/57/How-
Wind-Turbines-Work/

Build a wind generator that can light an LED
bulb!

http://www.learnengineering.org/2013/08/Wind-Turbine-Design.html

https://www.youtube.com/watch?v=qSWm_nprfqE

http://www.johnhearfield.com/Wind/Windmills.htm

http://science.howstuffworks.com/environmen
tal/green-science/wind-power3.htm
Generally speaking,
doubling the rotor
diameter produces
a four-fold increase
in energy output.
But unless you’re in
a high-wind area,
longer blades might
just get too heavy.
Longer blades also
increase DRAG.

*http://www.hcisd.org/cms/lib4/TX01001784/Centri
city/Domain/307/wind_turbinebladedesign.pdf

What if your LED won’t light up? It might need to have its
legs flipped around. Electrical current from a battery or
generator always flows in one direction, opposite to the
direction the electrons are moving in. We have a “positive”
and a “negative” side to batteries and other instruments to
help us orient them the correct way.
https://www.quora.com/Why-electrical-energy-is-a-form-of-kinetic-energy