The two-phase slug flow regime in horizontal cocurrent gas-liquid flow was studied for the case of the liquid phase containing small amounts of polyacrylamide, a drag-reducing long chain polymer. The experimental work was performed in a 2.54 cm I.D. horizontal test section 10.7 m long.
Results indicated that two-phase drag reduction was greater than in single phase flow at the same superficial liquid velocities. By the use of pressure drop results with and without polymer additive, and a knowledge of slug geometry, frequency, and velocity, it was possible to separate approximately the contribution to the pressure drop of liquid wall friction and slug intertial effects. In all cases, the acceleration term was important and is the major energy term at most flow conditions. The technique may be of general usefulness in determining accelerational effects in two phase flows.
When drag reducing agents have been added to a horizontal slug flow, the pressure loss can be correlated successfully both by the Lockhart-Martinelli type of relationship or by a universal drag reduction curve of the type proposed by Virk.