Jet Expansion of Gas with Near-Wall Liquid Film from Nozzle into Vacuum

Abstract

A structure of gas–droplet flow under the jet expansion of gas with near-wall liquid film from the cylindrical channel into vacuum is investigated experimentally. Such flows take place, for example, behind rocket thruster nozzle, cooled by the liquid fuel film moving on its inner surface. A case in point is the International space station (ISS) orientation thruster. Methods of flow structure visualization and measurements of droplet phase spatial distribution are described. It was discovered that near-wall liquid film moving down on an inner surface of the nozzle not only breaks up into droplets at the exit edge of the nozzle but also emerges onto the external surface of the nozzle, moving backwards on it, even against gravity. Gas–droplet flow behind the nozzle edge consists of two substantially different areas—central and peripheral. It was shown that near-wall liquid film breaks up into droplets at the exit part of the nozzle and on its external surface. And these droplets scatter practically in all directions.