Data Sheet
WHAT’S HAPPENING
When the wind comes to a hill, it is pushed upward at a faster speed.
That’s why the ideal location for a wind turbine is on top of a hill. For
optimal energy production, it makes sense to take advantage of this
“hill effect.”
If you stand between high buildings (or in a narrow mountain
pass), you can notice the same kind of effect. The air is
compressed on the windward side of a building. That can
raise its velocity quite a bit as it blows between the
obstacles around it. This phenomenon is known as
the “tunnel effect.”
Here’s an example: If the normal wind speed in an
open area is 6 m/s, it can reach a speed of 9 m/s in
that kind of tunnel. Through skillful selection of a
location in a tunnel, in other words, you can
increase wind speeds quite a lot relative to the
surrounding area.
Operating the wind
turbine outside
YOU WILL NEED
› Assembled wind turbine with attached LED
› 1.2-volt rechargeable AA battery (HR6/KR6)
› Cable ties
HERE’S HOW
1. As soon as you have gotten to know your
wind turbine, you can take it outside into its
“natural” environment. Take a look out the
window. Is the wind blowing? Ideally,
maybe a light breeze (see back cover)?
Okay, time to go outside.
2. Look for a place where you can attach your
wind turbine to something like a wooden
stake or a metal pipe. Ideally, find a free-
standing lawn umbrella stand or a wooden
stake that you can pound into the ground.
In that case, be sure to remove the wind
turbine’s base plate.
3.
Secure the wind turbine to the stake or pipe
with two cable ties. Make sure that
everything is tightly attached. If you do that, it will take a wind
strength of at least 4.5 m/s to knock your wind turbine over.
4. The best thing would be a movable attachment — in other words, if
you can easily take your wind turbine along with its stake or pipe to
another location and set it up there. If you can move it around, you
can easily find out where the wind is blowing the strongest. Right up
on top of a hill? Or at the foot of the hill, in its valley? And how
about between two buildings standing close together?
3
Hill effect
Tunnel effect
16
EXPERIMENT 3