Local Liquid Velocity in Vertical Air-Water Bubbly Downward Flow

Local characteristics of the liquid phase in downward air-water bubbly and slug flows were investigated in a 50.8-mm inner-diameter round pipe. A laser Doppler anemometry system was used to measure axial liquid velocity and its fluctuations. To reduce the measurement uncertainty, the experiments were performed in flow conditions with low void fraction. The comparisons between the liquid flow rates measured by the magnetic flow meter and those obtained from the local measurements showed good agreements. In addition, based on the LDA measurements and the data acquired by the local conductivity probes, the local relative velocity distribution, the distribution parameter and the drift velocity in the drift-flux model were obtained for the current downward flow.