Flow structure in horizontal oil–water flow

The flow structure occurring during the cocurrent flow of oil (1.6 mPa s viscosity and 801 kg/m3 density) and water was investigated using two 1-in. nominal bore horizontal test sections made from stainless steel and acrylic resin respectively. Two methods were used for the flow pattern identification, namely high speed video recording and determination of the local phase fractions with a high frequency impedance probe, while the continuous phase in dispersed flows was recognised with a conductivity needle probe. ements were made for mixture velocities varying from 0.2 to 3.9 m/s and input water volume fractions from 6% to 86%. Over this range of conditions, many different flow patterns were observed, ranging from stratified to fully mixed. Annular flow did not appear. In general, the mixed flow pattern appeared in the steel pipe at lower mixture velocities than in the acrylic pipe, where, also, oil was the continuous phase for a wider range of conditions. The visual observations were consistent with the measurements using the high frequency impedance probe. In certain ranges of conditions the distribution of the phases differed dramatically between the stainless steel and the acrylic pipes. The average in-situ velocity ratios of the two phases in the acrylic pipe calculated from the phase distribution measurements were in general lower than unity.