Numerical Simulation of Non-Equilibrium Two-Phase Wet Steam Flow through an Asymmetric Nozzle

Miah Alam,Toshiaki Setoguchi,Manabu Takao

doi:10.3390/fluids2040063

Miah Alam, Toshiaki Setoguchi + Show 1 more

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https://doi.org/10.3390/fluids2040063

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Abstract

The present study reported of the numerical investigation of a high-speed wet steam flow through an asymmetric nozzle. The spontaneous non-equilibrium homogeneous condensation of wet steam was numerically modeled based on the classical nucleation theory and droplet growth rate equation combined with the field conservations within the computational fluid dynamics (CFD) code of ANSYS Fluent 13.0. The equations describing droplet formations and interphase change were solved sequentially after solving the main flow conservation equations. The calculations were carried out assuming the flow two-dimensional, compressible, turbulent, and viscous. The SST k-ω model was used for modeling the turbulence within an unstructured mesh solver. The validation of numerical model was accomplished, and the results showed a good agreement between the numerical simulation and experimental data. The effect of spontaneous non-equilibrium condensation on the jet and shock structures was revealed, and the condensation shown a great influence on the jet structure.

Highlights

Phase transfer of steam from the gaseous to the liquid phase occurs close to equilibrium conditions only if the cooling rate is very small
The numerical scheme employed simulating the system of governing equations is the density-based solver within the commercial computational fluid dynamics (CFD) code of ANSYS Fluent 13.0 [21]
The influence of thermal parameter on the changes of onset of condensation was investigated by examining the nucleation region and liquid droplet growth

Summary

Introduction

Phase transfer of steam from the gaseous to the liquid phase occurs close to equilibrium conditions only if the cooling rate is very small. Non-equilibrium condensation arises in transonic/supersonic flows with a high cooling rate. This means that the time scale of flow is faster than the time scale of the phase transfer. As phase change affects the flow features, many numerical works have been conducted to model the non-equilibrium condensation phenomena in high-speed flows [1,2,3,4,5,6,7]. Many researchers have investigated the same condensation phenomena experimentally [8,9,10,11,12]

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