Tip-Speed Ratio ($\lambda = \frac{2 \pi R N}{V}$):

Where:

• $\lambda$ is the tip-speed ratio, a dimensionless number.
• $R$ is the rotor radius, in meters (m).
• $N$ is the rotor speed, in revolutions per second (rps).
• $V$ is the wind velocity, in meters per second (m/s).