New developments in the thermal hydraulic module THY of the COCOSYS program, part of the AC2 software package: turbulence in gaseous countercurrent flows

Abstract

AbstractCountercurrent gaseous flows may occur under certain conditions e.g. in narrow flow paths between compartments within containments of nuclear power plants (NPP) during design basis and beyond design basis accidents. Their potential effect on thermal-hydraulics within the containment is not sufficiently investigated yet. This publication focuses on modelling and numerical investigation of the physical phenomenon of pressure loss due to turbulence in such countercurrent gas-gas flows. Scenarios observed in the test facilities PANDA and THAI+ are being investigated. The important regimes of the countercurrent layered gaseous flows are identified and a mathematical model incorporating all the required regimes is introduced, implemented in the GRS program COCOSYS, tested and discussed in detail. The effects of the new model are numerically investigated. By means of a comparison with a CFD simulation, the model parameters are evaluated. It is suggested to improve the accuracy of the model with the help of future experiments.