Reynolds number calculation verification

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The discussion focuses on verifying the calculation of the Reynolds number for a wind turbine, emphasizing that it varies along the blade due to changes in chord length and velocity influenced by the tip speed ratio. The user calculates an average velocity using the formula Vavg = (v * lambda) / 2, where v is the free stream velocity and lambda is the tip speed ratio. They seek clarification on whether this average velocity is correct for calculating the Reynolds number using the formula (Vavg * l) / v*, where l is the average chord length and v* is the kinematic viscosity of air. Additionally, there is a request for a definition of the tip speed ratio. The conversation highlights the complexities involved in accurately calculating the Reynolds number for wind turbine blades.
Big_Dawg
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Hi guys,

I just wanted to verify my calculation of a reynolds number of a wind turbine. I understand that the reynolds number will vary in a spanwise direction along the blade due to changes in the characteristic length(chord width) and velocity(due to the tip speed ratio). As a way to approximate the reynolds number I've taken an average chord length.

v = 5 (free stream velocity)
lamda = 6 (tip speed ratio)
v* = kinematic visocity of air at 10degrees = 1.4207E-5
l = 0.5 (average chord length)

Now this is the part I am unsure of. Do I find an average velocity as follows for the calculation:

Vavg = (v*lamda)/2 (Average velocity)

and then calculate as follows:

(Vavg*l)/v*
 
Last edited:
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Units anyone?

What is a tip speed ratio? How is it defined?
 

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