Experimental Study on the Flow Patterns and Two-phase Pressure Drops in a Horizontal Impacting T- Junction

The present paper analyzes the experimental results concerning the flow patterns and pressure drops in two-phase flow through an horizontal impacting T-junction, whose outlet pipes are aligned and perpendicular to the inlet pipe. The test section consists of plexiglass pipes with inner diameter of 10 mm. A mixture of water and air at ambient temperature and pressures up to 2.4 bar flows through the T-junction, with different splitting of flow rates in the two outlet branches; superficial velocities of air and water in the inlet pipe are varied up to a maximum of 35 m/s and 3.5 m/s respectively. The flow patterns occurring in the inlet and branch pipes were compared with the predictions of Baker’s and Taitel – Dukler’s maps. The pressure drops along the branches have been measured relatively to different splitting of the flow rate through the two branches and the pressure loss coefficients in the junction have been evaluated. Friction pressure drops have allowed us to evaluate two-phase friction multipliers, which have then been compared to the predictions of Lockhart-Martinelli, and Friedel correlations. Local pressure drops were extrapolated at the junction centre and analyzed; the two-phase multiplier has been evaluated and compared with the predictions of Chisholm correlation; the value of the empirical coefficient that minimizes the discrepancies has also been evaluated.