Motion and Decay of Near-wall Liquid Film at Its Outflow with Cocurrent Gas Flow from the Cylindrical Channel into Vacuum

The problem of a liquid flow expelled into vacuum is interesting both in theoretical and practical aspects. In the fundamental framework, research of physical processes and phenomenon accompanying the outflow of a fluid into vacuum is of great importance: an instantaneous boiling, breaking into drops, phase transitions at the droplet surface and inside, the interaction of drops with supersonic flow, etc. As for practical applications the outflow of a fluid into vacuum is of interest, in particular, for space engineering from the point of view of contamination of a space vehicle surface during operation of its venting devices, operation and orientation thrusters, systems of refueling by propellants, etc [1]. Despite of certain interest to the given problem, the number of articles devoted to outflow of fluids and gas-liquid mixtures into vacuum is extremely limited. They deal mainly with water election into vacuum. At the same time there are a lot of items concerning research of pure gravity motion of liquid films [2]. As for film motion with cocurrent flow of gas, the number of such studies is rather great, however they are fulfilled mainly at pressures close to atmospheric and concerning low-level (subsonic) speeds of a gas flow [3]. One of features of the considered problem consists in the fact that most of liquids at the outflow into vacuum become overheated even at room temperature, that results in explosive rupture of a film with formation of a vapor phase and drops of a miscellaneous size. Other feature of the problem lies in strong effect of cocurrent gas flow on motion of the film inside the channel and at the outflow into vacuum.