Under some conditions, single phase adiabatic vapor flow inside a convergent-divergent nozzle passes the saturation line, loses its equilibrium state and turns into supersaturated (supercooled) vapor. Later, under the influence of intense expansion and supersonic acceleration of the flow in the divergent channel, the instability of the fluid intensifies. In the lack of external surfaces, this non-stable state causes nucleation and consequent growth of the formed nuclei. Finally, the process of nucleation and growth of droplets returns the flow to two-phase and to stable conditions. Due to the release of latent heat from condensation to the supersonic flow at the location of nucleation, an increase in pressure is developed in this small region which is known as the condensation shock. In this research, for the first time, the effects of this shock on the boundary layer parameters of the supersonic flow in the divergent section of the channel are investigated. First, the non-steady supersonic vapor flow which has the capability of nucleation is modeled analytically as adiabatic, inviscid and one dimensional. Then, using the mathematical equations of laminar and turbulent boundary layer parameters, including the displacement thickness, and using the Inviscid-Viscous Interaction method the effects of viscosity on the two-phase flow and also all boundary layer parameters along the channel are obtained. The results of these analytical modeling shows that although the influence of the boundary layer on the expansion flow is limited, it still causes approximately 3% increase in the diameter of the droplets. However,, the effects of two-phase flow on the boundary layer parameters at the location of the condensation shock is considerable. The major novelty of this research is determining the quantification and qualification of these effects.

Keywords