Influence of the gas and liquid superficial velocity on slug frequency

Slug flow is a kind of hazardous gas-liquid two-phase flow pattern encountered in pipelines and wells for natural gas production which may cause the vibration and destruction of the pipelines. An important parameter of slug flow is slug frequency, the study of which can be used to reduce the hazards of slug flow. In this research, a horizontal air-liquid two-phase flow test loop was constructed to study the influence of the gas and liquid superficial velocity on slug frequency. The PSD (Power Spectrum Density) and counting method were tried to analyze the frictional pressure drop signals to determine slug frequency, and the counting method with a lower threshold was considered as a better method and was finally used to obtain slug frequency quantitatively. A curve fitted by the slug frequency data of our experiment with the constant gas superficial velocity of 3 m/s and different liquid superficial velocities were compared with those of some former researchers' experiments. The results indicated that, the counting method with a lower threshold value can be used to determine slug frequency quantitatively; slug frequency increased significantly with the liquid superficial velocity, but it changed little with the gas superficial velocity; the difference between the slug frequency curve of our experiment and other curves increased obviously with the liquid superficial velocity.