Discussion on Difference between 3 Cup and Ultrasonic Anemometers of the Obtained Statistical Values to be Used for Wind Environment Assessment

Abstract

The criterion for wind environment assessment by Wind Engineering Institute Co., Ltd. is based on the relation between the mean wind speeds measured by 3 cup anemometers and the surrounding condition. Recently, ultrasonic anemometers with lower cost and higher performance has become popular and taken place of 3 cup anemometers; 3-cup anemometers respond to the wind speed change slowly for lower wind speeds while they tend to over-rotate for higher wind speeds due to the effect of inertia force. Considering this circumstances, the present paper investigates the difference between 3 cup anemometer and ultrasonic anemometer for the measured values. Based on the results, we propose a correction method for converting the measured values by 3 cup anemometers to those by ultrasonic anemometers.