Experimental database on steam-water flow with phase transfer in a vertical pipe

The evolution of steam-water flow with an initial sub-cooling along an 8 m long pipe with an inner diameter of about 200 mm was measured to obtain a database suitable for the qualification of CFD-codes on poly-dispersed flows with phase transfer. Phase transfer has to be considered in Nuclear Reactor Safety Research, e.g. in case of sub-cooled boiling or bubble entrainment caused by Emergency Core Cooling (ECC) injection. Bubble size distributions are important, since the phase transfer rate is proportional to the interfacial area density. To develop and validate closure models for CFD codes experimental data with high resolution in space and time are required. The experiments were conducted at the TOPFLOW facility of the Helmholtz-Zentrum Dresden-Rossendorf. Steam was injected into upwards flowing sub-cooled water via orifices in the pipe wall located at different distances from measuring plane. 1 mm and 4 mm injection orifices are used to vary the initial bubble size distribution. The variation of the distance between the location of the gas injection and the measuring plane allows investigating the evolution of the flow along the pipe. Pressure, steam and water flow rates and the sub-cooling were also varied. Measurements are done using wire-mesh sensors and thermocouples. Data on averaged void fraction, radial gas volume fraction profiles, profiles of the gas velocity and bubble size distributions in dependency of the L/D ratio are available.