Static pressure behavior of gas–liquid flows along a Venturi

• Published in: Journal of the Brazilian Society of Mechanical Sciences and Engineering 2021-11, Vol.43 (11), Article 498
• Main Authors: Costa, M. G., Leite, J. M., Beckedorff, L., Spengler, A. W., de Paiva, K. V., Oliveira, J. L. G.
• Format: Article
• Language: English
• Subjects: Air masses; Convergence; Diameters; Differential pressure; Engineering; Fast Fourier transformations; Flow control; Flow distribution; Fluid flow; Fourier transforms; Liquid flow; Mass flow rate; Mechanical Engineering; Multiphase flow; Reynolds number; Static pressure; Stratified flow; Technical Paper; Void fraction
• ISSN: 1678-5878; 1806-3691
• DOI: 10.1007/s40430-021-03203-1

The applicability of a multiphase flow meter consisting of a modified Venturi and an electrical capacitance tomography (ECT) was investigated with two-phase air–water horizontal flows. The ECT provides void fraction information, whereas the Venturi surface was machined to permit static pressure measurements along its streamwise direction. Experiments occurred with the mean void fraction ranging from 0.05 to 0.6, corresponding to bubbly, slug, and stratified flow patterns. Water and air mass flow rates were measured up to 2.24 kg/s and 0.0018 kg/s, respectively, and the gas and liquid Reynolds numbers, up to 7.2 × 10 4 and 3.2 × 10 3 , considering the Venturi inlet diameter. Liquid and gas instantaneous flow images were obtained with ECT. Flow pattern identification was possible through the application of the fast Fourier transform on differential pressure signals along the Venturi tube. An expression to obtain the liquid flow rate in air–water flows was provided as a function of the mean void fraction. A 90° elbow located five diameters upstream the converging Venturi end has displaced the “vena contracta” position in high-quality flows from the throat to the converging part. Typical static pressure behavior was observed for flows with a mean void fraction less than 0.2.