FLOW CHARACTERISTICS OF SLUG FLOW - STUDIES ON TWO-PHASE GAS-LIQUID FLOW IN VERTICAL PIPES. (4TH REPORT).

Flow characteristics of slug flow for upward flowing air-water mixtures including gas slug velocity, gas slug length, liquid slug length and void fraction profile, are discussed experimentally and/ or analytically in the present report. The experiments were carried out in three sizes of pipes that were used in the previous work and the analysis were done using the equations presented in the previous paper. The results are summarized as follows. The gas slug velocity was represented by an equation. However, it was shown that the coefficient C//1 is influenced slightly by the void fraction in the liquid slug region. The distribution of lengths of the gas and liquid slugs was described by a logarithmic normal distribution. The mean value and the standard deviation of gas slug length were expressed by empirical equations. The liquid slug length was insensitive to the gas and liquid flow rates and almost constant for a given tube diameter. The void fraction profile in the overall slug was denoted by the power law distribution. It was suggested from the analysis of liquid-phase velocity profile that the presence of small bubble in the liquid slug region brings a flattening effect on the velocity profile.