Off-axis characterization of ice-free anemometers

The main objective of this article is to analyze the angular (off-axis) response of heated cup anemometers designed specifically for wind power generation in cold climate. Three commercial heated cup anemometers are tested together with two ice-free prototypes developed as part of a broader research program focusing on ice-free sensors. Three indexes are proposed to allow better data analysis of angular response measurements. It is shown that careful attention to the anemometer geometry can lead to a nearly perfect cosine shape response while improper rotor geometry can lead to very bad angular response. A patented rotor geometry design is tested on different anemometers to see if one could expect the desired angular response for cup anemometers used in the wind energy industry to be obtained with such rotor geometry.