Вплив гідродинамічних збурень на точність вимірювання швидкості потоку ультразвуковими витратомірами газу

Abstract

The modeling of perturbed velocity profile of turbulent gas flow using computational fluid dynamics method (CFD) is carried out. The algorithm for determining the average velocity along the acoustic path is developed using the results of CFD-modeling. The effect of influence of flow profile distortions produced by the fitting "90° elbow" on the average velocity measurement error is investigated for single channel ultrasonic flowmeter with diametrical acoustic channels. Modeling of such flowmeter is carried out for various angles of the plane of diametrical acoustic channel (0°, 45°, 90° and 135°). The dependence of the relative deviation (error) of average velocity on the angle of acoustic channel and on the distance between the flowmeter and the fitting "90° elbow" is investigated. The angle of acoustic channel of ultrasonic flowmeter that provides the minimum error of flow velocity measurement downstream of fitting "90° elbow" is defined. The distance between the ultrasonic flowmeter and the fitting "90° elbow" is defined to provide the velocity measurement error smaller than 0.5%.