This paper represents an initiation for studying the influence of change of phase of a water vapour-inert gas mixture that acts upon moving projec-tile in a barrel experimentaly sustained by theoretical model.
In this study, the equations expressing the projectile motion and the change of state of the driving gas are analysed. In addition, the influence of boundary conditions is discussed. This is carried out for the purpose of determination of the calculation procedure which can be adapted in the case of two phase flow, if the condensation may take place by thearetical expectation. At the sametime,it is also to obtain the geomet-rical characteristics necessary for the construction of an experimental set-up for studying the condensation influences.
It was found that the theoretical model expressing the projectile motion and the change of state of gas, proved its accuracy by comparison with experimental results. It is proved also that even in these particular conditions of gas expansion,the condensation of water vapour can take place. A conclusion that an increase of projectile velocity has been proved if the water vapour is added to the propelling gas