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This paper deals with modeling in a vacuum chamber of the International Space Station (ISS) contamination processes caused by its orientation thrusters (OT), namely with experimental study of joint ejection of gas and near-wall liquid film from a supersonic nozzle into vacuum. The description of experimental setup and measurement techniques is presented in the paper. Local parameters of near-wall liquid film-its thickness and velocity at the nozzle outlet are measured. It is shown that film thickness and velocity do not depend on nozzle orientation, i.e. measurement results are not influenced by gravity. The structure of droplet phase flow arising behind the exit cross-section of a supersonic nozzle in vacuum under microgravity conditions is obtained. Results are confirmed by three independent measurement techniques. Appearance of droplet phase backflows which cause contamination of space station exterior is shown. The way of space station contamination minimization is suggested. It is shown that using of special gas-dynamical protective devices-screens, mounted at the exit part of a nozzle, allows to reduce phenomenon of contaminating back flows significantly. Carried out space experiment Kromka showed good correspondence of real experiment results with results of model experiment. It also approved the suggested way of ISS contamination minimization.

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We present the experimental research on the interaction of co-current gas flow with near-wall liquid film for gas velocities up to 300 m/s. Local parameters of near-wall liquid film are measured by using capacitytype probes. It is shown that co-current gas flow has strong influence on near-wall liquid film, leading to intensive wave formation, detachment of droplets from the film surface and their entrainment by the gas flow. Thus it is shown that the relative amount of liquid carried away by co-current gas flow is well characterized by Weber number of gas flow. A model for the motion of a film with co-current flow, connecting a thickness and velocity of the film with value of shearing stress at gas-liquid boundary, is suggested. It is shown that intensive wave formation leads to essential increase of the interphase friction value.