DOI: 10.1615/THMT-18
ISBN Print: 978-1-56700-468-7
ISBN Online: 978-1-56700-467-0
ISSN Print: 2377-2816
Detection and measurement of bubbles in gas-liquid two-phase flow using magnetic fields
ABSTRAKT
A method for measuring the velocity and the size of slugs in gas-liquid two-phase flow is presented. It is based on the magnetic forces that arise from the different susceptibilities of the gas and liquid in the presence of an external magnetic field. Equal but opposite magnetic forces act on the interface and the magnet system. As a consequence two peaks appear in the force signal measured on the external magnet when an elongated bubble traverses the magnetic field: one for the bubble front and one for the back of the bubble. The force peaks can be used to calculate the velocity and the size of single bubbles. We have investigated elongated bubbles with a length of 0.1 − 0.25 m at different velocities. But also small bubbles with a diameter in the range of 10-3 m can be detected. In contrast to other two-phase flow measurement techniques this method can be applied to opaque, hot or corrosive fluids because it is contactless and non-invasive. Furthermore the method can be extended to liquid-liquid two-phase flows and to solid body measurements with regard to nondestructive testing.