Study of drag reduction by gas injection for power-law fluid flow in horizontal stratified and slug flow regimes

摘要

In this work,the drag reduction by gas injection for power-law fluid flow in stratified and slug flow regimes has been studied.Experiments were conducted to measure the pressure gradient within air/CMC solutions in a horizontal Plexiglas pipe that had a diameter of 50 mm and a length of 30 m.The drag reduction ratio in stratified flow regime was predicted using the two-fluid model.The results showed that the drag reduction should occur over the large range of the liquid holdup when the flow behaviour index remained at the low value.Furthermore,for turbulent gas-laminar liquid stratified flow,the drag reduction by gas injection for Newtonian fluid was more effective than that for shear-shinning fluid,when the dimensionless liquid height remained in the area of high value.The pressure gradient model for a gas/Newtonian liquid slug flow was extended to liquids possessing the Ostwald-de Waele power law model.The proposed model was validated against 340 experimental data point over a wide range of operating conditions,fluid characteristics and pipe diameters.The dimensionless pressure drop predicted was well inside the 20% deviation region for most of the experimental data.These results substantiated the general validity of the model presented for gason-Newtonian two-phase slug flows.