Abstract
hree- and four-bladed windmill-anemometers and cupanemometers are started from rest in the wind tunnel and are also stopped from rotation in a still air, and their responses are compared with one another. The static torque coefficients are calculated from the observation of rotational speed versus time to be used in SCHRENK's parameter. SCHRENK's overestimation factors for both anemometers are evaluated into a single chart for rectangular wind waves. For sinusoidal wind waves, graphical solution of the equation of motion is carried out, from which the over-estimation factor is computed and compared with experiment due to DEACON. The phase lag is also obtained into a chart.
