Simulation of Spontaneous Condensation of Viscous SteamFlow in Low-Pressure Convergent-Divergent Nozzles

Abstract

The present study describes the results of experimental and numerical investigation of wet steam flow in low-pressure convergent-divergent nozzles and deals with the effects of turbulence on the process of homogeneous condensation. The experimental investigation consist mainly the axial pressure distribution of a fixed nozzle test section. The mathematical model that described the droplet nucleation and the growth rates combined with the field conservations was treated numerically within the CFD code FLUENT 6.3., in which the computational domain is discretized in a general unstructured mesh that is locally refinedespecially in the area of the spontaneous nucleation zone. The equations describing droplet formations and interphase change are solved sequentially after solving the main flow conservation equations. The calculations were carried out assuming that the flow is twodimensional, compressible, turbulent and viscous. The aimof the present study is the use of the modified k-ε model for modeling the turbulence within an unstructured mesh solver. The results obtained from the numerical part of the current analysis are compared with theexperimental results and gave an acceptable agreement. Also present experimental and numerical results showed good agreements with numerical and experimental existing published data.