The Experimental Study Of Flow Patterns In Gas-Liquid Two-Phase Flow

This thesis mainly studied the flow patterns in adiabatic water-air two-phase flow under non-rolling condition through experiment, which were conducted in horizontal, inclined and vertical tubes.Experiments were performed in a water-air two-phase system at atmospheric pressure. The flow patterns were mainly identified by visual observation. The experimental installation consisted of a 6 m long transparent pipe with exit open to atmosphere. For horizontal flow, tubes of three different inside diameters: 14.8mm,24.5 mm and 34.5 mm were used respectively, for inclined flow, 14.8 mm and 24.5 mm tubes at 15° and 30°, and for upward vertical flow, 24.5 mm and 34.5 mm tubes. The experimental data were timely collected and recorded by computer accumulation system. Typical flow patterns were taken photos using 1000 frames per second high-speed camera. At low flow rate, flow patterns were directly recognized by optical observation, at high flow rate, by a combination of camera and pressure/pressure drop fluctuation.The experimental results together with large amounts of phenomena were used to ascertain the flow patterns, and to classify them according to common determination. Flow patterns maps for horizontal flow in 14. 8 mm,24.5 mm and 34.5 mm pipes; for inclined upward flow in 14.5 mm and 24.5 mm tubes at 15° and 30°; for upward vertical flow in 24.5 mm and 34.5 mm pipes, were drawn respectively. Flow patterns evolutions were described in detail, transition mechanisms were analyzed for each individual boundary, and corresponding mechanism models were presented.It was found that the flow patterns maps drawn for horizontal and inclined flow were basically coincide with previous flow maps, such as Mandhane maps and Barnea maps. It showed by comparison of horizontal and inclined flow maps as follows. (1) The transition region from stratified to intermittent flow is different: stratified flow disappears in inclined pipes and intermittent flow region enlarges. (2) The annular flow transition boundary is associated with inclined angle, and is deviated to higher gas flow rate with increasing angle. (3) The bubble flow, slug flow and annular flow occur in the whole angle region.