In flight mechanics, the “Coefficient of Power” (Cp) is a dimensionless parameter used to characterize the efficiency of a propeller or a wind turbine. It quantifies the conversion of power from the fluid (air) into useful work (thrust for a propeller or mechanical power for a wind turbine). Cp is particularly important in assessing the performance of these devices in various operating conditions.
Cp = P / ( ρ * n^3 * d^5)
where: Cp = Coefficient of Power (dimensionless) P = Power required (mechanical power output, typically in watts or kilowatts) ρ = Air density (density of the air, typically in kg/m³) n = Rotational speed of the wind turbine rotor (in revolutions per unit of time) d = Diameter of the wind turbine rotor (typically in meters)