Abstract: A numerical investigation is carried out for the phase change in the unsteady expansion of humid gases. The research is mainly focused on the process of water vapor non-equilibrium condensation in the presence of nitrogen and the influence of the condensation on the flow field in a shock tube. It is shown that the parameters of the flow field are disturbed and a condensation shock is generated due to the sudden release of the latent heat of condensation. With the condensation shock, the parameters and the structure of the flow field change dramatically.

Key words: water vapor, nucleation, condensation, expansion wave