Analysis of flow oscillations in a natural circulation system taking account of non-equilibrium boiling and void flashing / Untersuchung von Strömungsoszillationen in einem Naturumlaufsystem unter Berücksichtigung von unterkühltem Sieden und Selbstsieden.

Abstract

Flow oscillations in a test loop are simulated by a one-dimensional two-phase flow drift model with conservation equations for mass, steam, energy and momentum. Stability boundaries are evaluated in dependence on heat flux and subcooling by dynamical stability analysis in the time domain. It turns out that non-equilibrium boiling in the heat section and void flashing in the riser have a significant influence on flow instability in a natural circulation system at low steam quality and low system pressure.