自20世纪20年代末气举原理应用于油井生产以来，气液混合物垂直流动的研究一直受到关注。A、 单相流的物理描述通常在层流、湍流或过渡区中给出。对于两相流，气相和液相几乎总是分离的，至少部分分离，因此，物理描述需要说明相在管截面中的分布方式。这是通过对不同的两相流结构（称为流型）进行分类来实现的。以往研究的大部分注意力都集中在“流程图”的开发上，以将观察到的流型与各种流动变量关联起来。 其他研究涉及计算气液两相流压降的方法的发展。这里需要了解持液率，通常包括预测持液率的方法。

Investigations of vertical flow for gas-liquid mixtures have received attention since the late 1920's when gas-lift principles were applied to oil-well production. A, physical description of single phase flow is usually given adequately as in the laminar, turbulent, or transition regions. For two-phase flow the gas and liquid phases are nearly always separated, at least in part, A physical description, therefore, requires a specification of how the phases are distributed in the tube cross section. This is done by classifying different two-phase flow configurations, called flow patterns.Much of the attention of previous investigations has been in the development of "flow maps" to correlate the observed flow patterns with various flow variables. Other investigations have been concerned with the development of methods to calculate the pressure drop of a two-phase gas-liquid flow. Here a knowledge of the liquid hold-up is required, and methods for its prediction are usually included.