Fast Wire-Mesh Sensor for Two-Phase Flow Visualisation with 10 000 Frames per Second

The paper presents a new wire-mesh sensor for the fast visualisation of gas-liquid flows with a rate of 10 000 frames per second based on the measurement of the local instantaneous conductivity of the two-phase mixture. With this resolution it is now possible to visualise and quantify individual bubbles at mixture velocities of about 10 m/s. The sensor consists of two electrode grids with 16 electrodes each, placed at a small axial distance behind each other. The conductivity is measured at the crossing points of the wires of the two grids. The high measuring rate was achieved by applying an integrated digital signal processor for the control of the signal acquisition process. For the link to the data acquisition PC an ETHERNET interface is used. The internal memory is sufficient to store 170,000 frames, i.e. a continuous measurement over 17 s is possible. In the paper, results obtained in a vertical two-phase air-water flow are presented.