High-speed measurement of the void fraction distribution in ducts by wire-mesh sensors

The paper presents a wire-mesh sensor for high-speed visualisation of transient gas fraction distributions in two-phase flows. It is based on the measurement of the local instantaneous conductivity of the two-phase mixture. The maximum time resolution of the device is 10 000 frames per second. The sensor consists of two electrode grids with 16 electrodes each. This results in 16 x 16 sensitive points, which are equally distributed over the cross section. The sensor was used to measure gas fraction and velocity profiles, bubble size distributions and their evolution along the flow path in a vertical upwards gas-liquid flow.