An experimental investigation on the intermittent air-water flow in horizontal pipes

This work presents the results of an experimental investigation on the intermittent air-water flow in horizontal pipes, both with a constant diameter (0.06 m and 0.08 m i.d. respectively) and with a sudden area contraction (from 0.08 m to 0.06 m i.d.). Single fiber optical probes allowed to measure the so-called phase density function, whose time average is the local void fraction. The void fraction was measured in several points of seven cross-sections of the pipe with the sudden contraction, and of two cross-sections of the straight pipes, with a constant liquid mass flow rate of 3 kg/s and a gas volume fraction ranging from 0.2 to 0.8.; the duration of each measurement was 400s in order to get steady average quantities.