Measurement of Gas Phase Distribution Using Multifiber Optical Probes in a Two-Phase Flow

Gas detection is of great importance for the characterization of gas-liquid two-phase flow structures. Gas holdup distributions in gas-liquid slug and churn flows are experimentally investigated with a distributed multi-fiber optical probes (MFOP). The MFOP composed by 16 optical fiber probes is designed for a vertical upward pipe with 20 mm inner diameter. The cone angle of optical probe was determined by the energy of reflected light. Gas holdup on different positions at pipe cross section are acquired by processing the fluctuating signals of the MFOP. Thereafter, we verified the accuracy of the MFOP in gas holdup measurement using quick closing valves (QCV). Furthermore, gas holdup distribution at the whole pipe cross section is obtained by cubic spline interpolation. The research results indicate that local gas holdup distribution of liquid slug in slug flow is dependent on the length of gas slug. For gas holdup distribution of churn flow without large bubbles, the maximum of gas holdup sometimes occurs deviates from the pipe center, due to the bubble groups randomly flow in the pipe.