Direct Imaging of Two-Phase Flows by Electrical Impedance Measurements

Eric HERVIEU* and Paulo SELEGHIM Junior#

*Commissariat à l'Energie Atomique, DRN / DTP / SMTH / LATA 38054 Grenoble cedex 9, France

eric.hervieu@cea.fr

#Universidade de São Paulo, EESC – SEM, Av. Dr. Carlos Botelho, 1465 13560-970 São Carlos – SP, Brazil

seleghim@sc.usp.br

Abstract - This paper presents a two-phase flow direct imaging sensor, based on multiple electrical impedance measurements. The electrode configuration is optimized to provide imaged information on the phase distribution within the probe's sensing volume. As a consequence, the time evolution of the flow topology can be represented by simply plotting the signals corresponding to the peripheral impedance measurements, and therefore needs no numerical reconstruction from the experimental data. Several transient tests are performed in a two-phase air- water loop. They demonstrate that the sensor exhibits not only large structures such as slugs and plugs, but also some finer details such as the wavy or rugged interface in stratified flow, or such as the liquid film drainage during the transition between intermittent and annular flows. The methodology proposed in the present work constitutes a simple and inexpensive alternative to tomographic imaging techniques, and is thus fully adapted to online process monitoring of multiphase flow systems.

Keywords : Flow Monitoring – Impedance Sensor – Direct Imaging – Two-Phase Flows.