Experimental Study of the International Space Station Contamination by Its Orientation Thrusters Jets

Abstract

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.