Notes based on a session during the Centre for Alternative Technology Windpower Course
Notes written and taught by Hugh Piggott
with input from Claus
Nybroe.
Hugh
Piggott writes:
The first time I did this talk at CAT they threw me in with
no preparation, "Just come as you are!" and I had to wave my
arms about a lot. Since then I have done it countless
times, but I still get more than a few blank looks. It's
probably the most obscure bit of the course. Finally after
about ten years, I have produced a full set of notes. I am
so pleased, I asked Ian to put it on his site, and he has!
Thanks Ian. Sorry I did not explain Betz's theorem, or 'tip
speed ratio'. Buy my book 'Windpower Workshop' and read the whole story :-)
The notes are a series of graphics file documents (GIFs)
written in a logical order. You can print out the GIFs, but
first check they fit on your paper. If not, then use the
Page Setup menu and reduce the scale to 90%. To load just
the GIFs, start by clicking here
and then click on one of the GIF filenames.
Or simply surf the site, clicking your way between
these pages, using forward and back buttons
Defining drag vs lift forces page 1
Finite element blade
design page 2
The maths of lift and drag page
3
Setting the best blade angle page 4
Shape of the apparent wind page 5
Optimising the chord width page 6
'Back of an envelope' design page
7
Factors affecting power coefficient page 8
Ideal shapes and practical limits page 9
Pros and cons of high speed rotors page 10
Picture showing the variation of size and twist
in a 2.3mdiameter wooden windmill blade - Blade sections
Useful Links :
Books by Hugh Piggott Booklist
BWEA site about building your own wind turbine factsheet
Another introduction to blade design
More wind turbine words of wisdom from Herr
Doerner
A compilation of e-mail chat about small wind turbines the awea FAQ
A list from Mick Sagrillo (in 1990) of windmill plans
Alfred Forbes page:
homebuilt dynamo
Paul Gipe's excellent book Windpower for Home
and Business
The Centre for Alternative Technology Windpower Course at CAT in Wales.
