Experimental studies of multiphase flow in horizontal and inclined pipes

The scope of this work is to gain insight into the behaviour of two-phase flow in horizontal and downward inclined pipes. An experimental flow facility was built to investigate flow patterns developed over three pipe orientations of 0º, -15º and -30º, using air-water as the fluid combination and a 19 mm diameter test section. Superficial velocities for air ranged from 0.5 to 5.0 m/s with an increment of 0.5 m/s and for water from 0.1 m/s to 0.9 m/s with a 0.1 m/s increment. Flow visualization was conducted for flow pattern identification, and a high-speed video system was employed to obtain image sequence of the flow under different pre-selected conditions. Flow pattern maps were developed showing the effect of pipe orientation on flow pattern transition. Liquid hold-up, using a volume collection method, and pressure drop, using a differential pressure transducer, were measured. Also, stratified to slug flow transition regime in horizontal pipes was investigated using a non-intrusive optical technique – Particle Image Velocimetry (PIV) – to evaluate the velocity field of the liquid phase. This was achieved by the application of a PIV laser-induced fluorescence technique (LIF), whereby seeding particles impregnated with fluorescent dye (Rhodamine B); Fluorescent Polymer Particles 20-50 micrometers, 100g was used. The main aim here was to attain a thorough physical understanding of the internal flow structure of the two-phase flow transition regime with a view to providing an experimental database of results to the CFD research community for the validation of their numerical predictions. In particular, experimental data has been acquired in the form of an instantaneous velocity field (radial and axial velocities in the vertical cross section of the pipeline as well as distribution of velocity magnitude) together with the resulting vorticity field in the liquid phase. The results obtained have been discussed in detail and recommendations for future work have been outlined.