Cup Anemometer Behavior in Turbulent Environments

Abstract The behavior of the cup anemometer rotor in turbulent atmospheric flow is discussed in terms of a general equation of motion. This equates the rate of change s of the rotation rate s of the rotor to a forcing F(s, h, w), which is proportional to the torque and a function of s and of the total horizontal and the vertical wind velocity components, h, and w, respectively. To determine the so-called overspeeding, it is necessary to carry out first-and second-order perturbation calculations around the response curve obtained in a laminar flow. From this curve, which for the purpose of this paper can be considered linear, five constraints are derived between the first and second partial derivatives of F. These constraints provide sufficient information for deriving an expression for the overspeeding to which four distinctly different biases contribute—one for each of the velocity components and one from the covariance between streamwise velocity components ũ and w. A phenomenological model of...