Drag reduction in vertical annular air-water flow

Experiments of drag reduction in two-phase vertical upward annular flow are presented. The experiments were conducted in a 22.12 m long, 2.54 cm I.D. pipe. Air and water flowing at a pressure of 182--526 kPa were used. Gas flow rates ranged from 14.2--46.3 g/s while liquid flow rates were 148--278 g/s. The drag reducer was a high molecular weight co-polymer of polyacrylamide and sodium acrylate.;The drag reducing additive was effective in reducing the frictional pressure gradient. Results indicate that drag reduction is a function of both gas/liquid flow rate ratios and the concentration of polymer added. Overall, the best case scenario shows drag reduction of 82%. This was accompanied by an increase in liquid holdup and film thickness; therefore, greater liquid lift.;Degradation of the polymer was also investigated. An explanation is presented based on the operation of the pump and separator used.