Reynolds number calculation verification

In summary, the conversation is about verifying the calculation of a reynolds number for a wind turbine. The speaker mentions that the reynolds number varies in a spanwise direction due to changes in characteristic length and velocity. They then explain that they have taken an average chord length as an approximation. The speaker also mentions the values for free stream velocity, tip speed ratio, kinematic viscosity of air, and average chord length. They then express uncertainty about how to calculate the average velocity and pose a question about units. The last question is about the definition of a tip speed ratio.
  • #1
Big_Dawg
2
0
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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  • #2
Units anyone?

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

Related to Reynolds number calculation verification

1. What is Reynolds number?

Reynolds number is a dimensionless quantity used in fluid mechanics to predict the type of flow in a fluid system. It is calculated by dividing the product of a fluid's density, velocity, and characteristic length by its dynamic viscosity.

2. Why is Reynolds number important?

Reynolds number helps determine whether the flow in a fluid system is laminar or turbulent. This is important because it affects the efficiency of heat transfer, fluid mixing, and the development of boundary layers.

3. How is Reynolds number calculated?

Reynolds number is calculated by dividing the product of a fluid's density, velocity, and characteristic length by its dynamic viscosity. The characteristic length can vary depending on the type of flow and the geometry of the system.

4. How do you verify the accuracy of a Reynolds number calculation?

The accuracy of a Reynolds number calculation can be verified by comparing it to known values from experimental data or by using mathematical models that have been validated through experimentation. Additionally, using a higher number of significant figures in the calculation can increase accuracy.

5. What is the significance of the dimensionless value of Reynolds number?

The dimensionless value of Reynolds number allows for comparisons to be made between different fluid systems with different sizes, velocities, and viscosities. It also provides a universal scale for determining the type of flow and predicting the behavior of a fluid system.

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