Development of a reference method for the measurement of the ventilation rate through rectangular ventilation openings using ultrasonic anemometers

A measurement method for the airflow rate through rectangular ducts was developed with the use of 2D and 3D ultrasonic anemometers. The measurements were carried out 0.15 duct diameters (Dd) upstream and 0.37 Dd downstream of the outlet of a 1 m wide rectangular duct (1.0 m x 0.5 m) and 0.29 Dd downstream of the outlet of a 3 m wide rectangular duct (3.0 m x 0.5 m). An automated sensor frame was developed to automatically measure consecutive sampling positions. Experiments under varying conditions of flow profile, airflow rate and duct size were carried out. These experiments are a first step towards the implementation of such a method in naturally ventilated systems