Simulation of a counter-current horizontal gas-liquid flow experiment at the WENKA channel using a droplet entrainment model

Highlights: • A new droplet entrainment model was validated against a WENKA experiment. • High speed videometry and planar particle image velocimetry was used. • The agreement of the experimental findings and CFD results is acceptable. - Abstract: Usually droplet formation mechanisms are missing in standard fluid dynamics codes. However, for self-generating waves and slugs, the interfacial momentum exchange and the turbulence parameters ought to be modelled adequately. Furthermore, knowledge and thinking about the mechanism of droplet entrainment for heat and mass transfer processes is of high importance in the nuclear industry. Consequently a step of progress of modelling liquid/gas interfaces is the consideration of droplet entrainment model. The suggested model assumes that due to liquid turbulence the interface gets uneven and wavy leading to the creation of droplets. The model is validated against existing horizontal two-phase flow data from the WENKA (Water ENtrainment Channel KArlsruhe) channel. Experiments were taken out for an air/water system at ambient pressure and temperature. High speed videometry was used to get velocities from flow pattern maps of the counter current flow. In the horizontal part of the channel with partially reversed flow the fluid velocities were conducted by planar particle image velocimetry. An experiment with droplet generation at the reversed flow conditions was utilized to compare it with the simulation data. The agreement of the experimental findings and CFD results is more than satisfactory. Also the droplet mass flow was compared and showed the applicability of the droplet entrainment model. Further work is necessary to validate the model for different flow conditions.