Experimental Characterization of Gas-Liquid Downward Flow

With an increasing interest in downward two-phase flow, this paper contributes to the literature with a complete set of two-phase flow measurements, including flow pattern, liquid holdup, pressure gradient, and wall shear stress. Low-viscosity oil and air in a 21 m long and 5.08 cm inner diameter downward inclined pipeline (-15 and -30°) have been used. Superficial liquid and gas velocities are varied from 0.1 to 1.6 m/s and 1 to 7 m/s, respectively. In addition, the experimental results are compared to the predictions of existing mechanistic models for pressure gradient, liquid holdup, and wall shear stress.