RE: EZB Pitch Specifications way OT

From: John Barker <john.barker783_at_ntlworld.com>
Date: Wed, 11 Sep 2013 12:55:51 +0100

Neil,

I have never given much thought to Wind Turbines so I checked in Google and
the Tip Speed ratio is, as you would expect, the ratio of the tip speed to
the wind speed. This would not give an indication of the angle of attack
but of the blade angle required at the tip. If you draw a right angle
triangle with a base line of a length to represent the rotational speed and
a vertical side at one end of the base line to represent the wind speed then
complete the triangle with a sloping line. The angle between the base line
and the sloping line will be roughly the blade angle required at the tip.
An angle of attack must be added to this angle. I was wrong to say that J
is indicative of the angle of attack, it is numerically nearer to the P/D
ratio.

I mentioned that I don't make much use of J. Perhaps this is because I read
a lot of the great aerodynamicist, Glauart. He eschewed the use of J and
went directly to the ratio of tip speed to rotational speed in a lot of his
work for which he used the Greek letter Lambda. I notice that after about
80 years that Wind Turbine designers are still using Lambda for the tip
speed ratio.

John


 

 

From: Indoor_Construction_at_yahoogroups.com
[mailto:Indoor_Construction_at_yahoogroups.com] On Behalf Of Neil Dennis
Sent: 10 September 2013 14:36
To: Indoor_Construction_at_yahoogroups.com
Subject: [Indoor_Construction] EZB Pitch Specifications way OT

 

  

John, I've heard the term "tip speed ratio" used on wind turbines,
wonder if that is similar to AoA ?

wombat
Received on Wed Sep 11 2013 - 04:55:55 CEST