Influence of disturbed flow after an elbow on metrological properties of a Flow Averaging Tube

Experimental results of air velocity profiles and Flow Averaging Tubes (FAT®) K-factor measured behind an elbow are presented in this paper. The pipeline diameter was D=150 mm, while the range of mean velocities w=9…30 m/s. Velocity profiles were determined both in the vertical and horizontal plane in the respective distances L/D of a pipeline from 3 to 18. In the places of the measured velocity profiles, three cross-sections of flow averaging tubes (circular, streamlined and two-profile) were placed to determine the characteristics of K-factor. Moreover, a fully automated test stand is presented in this paper. The completed experiment allows shortening the distance between an elbow and a flowmeter installation place and informing about the value of a correction factor, which can be used to minimize the measurement uncertainty of the air flow rate. It was stated that the horizontal plane is better to install a probe because of the velocity profile and better results of repeatability.