Air Water Two-phase Flow in a Horizontal T- junction: Flow Patterns, Phase Separation and Pressure Drops

Il Congresso nazionale negli ultimi anni ha sempre più assunto una rilevanza internazionale, con articoli, invited lectures e presentazioni in inglese. Il Comitato scientifico include alcuni studiosi stranieri. This paper reports further results of the experimental campaign on two-phase flow in horizontal T-junction that has being carried out in the thermal-hydraulics laboratory of Dipartimento di Energetica of Politecnico di Torino since 2005. The test facility is provided with a dividing T-junction, used in the branching configuration. The pipes forming the tee junction are about 1 m long, their inner diameter is 10 mm and a mixture of air and water flows at pressures up to 1.5 barg. The present work reports the results with water superficial velocities in the range 0.95-3.61 m/s and air superficial velocities in the range 0.44-34.5 m/s. Flow patterns were also visualised systematically by filming the flow patterns across the three pipes in each experimental run. As far as the evaluation of pressure drops is concerned, experimental results are used to modify the Separated Flow Model: the Zuber formulation for the void fraction is adopted and both the pressure drop correction factor and local pressure loss coefficient are expressed as function not only of the extraction ratio but also of the flow pattern.