A review on numerical modelling of flashing flow with application to nuclear safety analysis


A review on numerical modelling of flashing flow with application to nuclear safety analysis

Liao, Y.; Lucas, D.

The flashing flow is an relevant multiphase phenomenon in many technical applications including nuclear safety analysis, which has been the subject of intense research. Numerical studies have evolved from one-dimensional to multi-dimensional. A variety of methods have been proposed, while a broad consensus was not exiting. The present work aims to present an overview of available models as well their assumptions and limitations by conducting a literature survey. The final focus was put on recent computational fluid dynamics simulations. Some consensus on modelling interfacial slip, phase change mechanism and bubble size is identified. Since flashing scenarios often accompanying with high void fraction and broad bubble size range, a poly-disperse two-fluid model is recommended. Thermal phase change model is superior to pressure phase change, relaxation and equilibrium models for practical flashing problems. Major challenges include improving closure models for interphase transfer, bubble dynamics processes, interfacial area as well two-phase turbulence. For this purpose, high-resolution high quality experimental data are important, which are lacking in many cases. Considering that heterogeneous gas structures often exist in flashing flows, multi-field approaches able to handle different shapes of gas-liquid interface are recommended.

Keywords: computational fluid dynamics; flashing flow; nuclear safety analysis; numerical modelling; literature review

Downloads

Permalink: https://www.hzdr.de/publications/Publ-31151
Publ.-Id: 31151