Study of flow pattern discrimination in vertical gas-liquid two-phase flow based on the characteristics of void fraction waves

Void fraction waves of various flow patterns in vertical gas-liquid two-phase flow were obtained from experiments. The probability distribution function (PDF) and spectral distribution of various basic flow patterns such as bubble flow, cap bubble flow, slug flow and churn flow were gained by means of signal processing. The results indicate that the characteristics of void fraction waves, PDF and spectral distribution of different flow patterns are different. With the increase of void fraction, the frequencies of void fraction waves come to single. Therefore, on condition of invisualization, different flow patterns can be distinguished by means of curve characteristics above, especially the PDF distribution curves.