Near-wall liquid film ejection with co-current gas flow from nozzle into vacuum

•Ejection of wall liquid film into vacuum and into atmosphere is drastically different.•Near-wall liquid film moves on external surface of a nozzle against gravity.•Disintegration of liquid film into droplets with backflows formation takes place.

The recently discovered phenomenon of near-wall liquid film rise against gravity on an external surface of a nozzle under joint ejection with co-current gas flow into vacuum is studied experimentally for a variety of liquids and ejection regimes. It is shown that co-current gas flow parameters, pressure in surrounding space (in vacuum chamber) and physical properties of liquid (primarily saturated vapor pressure and heat of evaporation) have the main influence on behavior of a near-wall film at the exit edge of the nozzle. Quantitative data on height of liquid film rise for different liquids and different conditions of ejection are obtained. Possible theories that account for the film rise against gravity on the external surface of the nozzle are discussed.