Transient Gas-Liquid Flow in Upward Sloping Pipes, Approaching the Wavy-to-Slug Flow Transition

Abstract

A model is presented for transient, cocurrent gas-liquid pipe flow in the stratified-smooth and stratified-wavy flow regimes. It is based on the equations of continuity and motion in the direction of flow and results in two hyperbolic partial differential equations, which are solved numerically using the combined methods of lines (Schiesser, 1991) and characteristics (Stoker, 1957). In wavy gas-liquid pipe flow, three different interfacial areas and corresponding shear stresses are identified. Three friction-factor correlations were derived on the basis of an extensive set of 2500 steady-state measurements. The transient behavior of inclined gas-liquid pipe flow is successfully simulated and compares well with the results obtained from on-line measurements, right up to the onset of slug flow.