Response of Cup Anemometer in Turbulence

Abstract

Taking account of the force arising from the relative wind velocity between the cup and the wind, the differential equation of rotation of cup assembly was formulated. Dynamic responses of cup anemometers to the stepwise and sinusoidal wind changes and to turbulent fluctuations of wind speed were numerically examined. And the damping rate of amplitude and the phase lag in measuring fluctuating wind, and the over-estimation factor in measuring mean wind speed were estimated. These characteristics of the cup anemometer may be expressed according to two constants, which are the calibration constant and the response distance of anemometer. The errors in measured mean wind speed are presented for typical turbulent winds of "wind over sea" and "wind over land".