Comparison of bubble velocity components in a swirling gas-liquid pipe flow using dual-plane EIT and a novel 4-sensor local probe

A comparison is made of the distributions of the local axial, radial and azimuthal velocity components obtained from a dual-plane EIT system and a local 4-sensor conductance probe in a swirling two phase pipe flow. The paper describes a dual-plane EIT system and how the local axial, radial and azimuthal gas velocity components can be obtained using best pixel correlation. A mathematical model is then presented showing how the bubble velocity vector and hence three orthogonal bubble velocities can also be calculated from seven time intervals taken from the output signals from each of four conductance sensors located within the local 4-sensor probe. Results are presented for both measurement systems, comparing the distributions of the gas velocity components in a swirling, bubbly, vertical pipe flow. It was found that the presence of swirl causes the gas to have a significant azimuthal velocity which increases in magnitude from the pipe centre to the pipe wall.