CFD STUDY OF THE DEVELOPMENT OF INTER-SUBCHANNEL ISOTHERMAL LAMINAR FLOWS

Abstract

The design and optimization of nuclear reactors, specifically in the case of CANDU, involves the study of subchannel flows. The mixing inside the subchannels is crucial to the efficiency of heat transfer between the fuel rods and the coolant. Numerous studies have been done throughout the past few decades regarding the physics of subchannel flows, most of which being inside the turbulent regime. Despite the fact that subchannel flows in nuclear reactors are turbulent in nature, studies have shown that flow pulsations inside subchannels can occur under laminar conditions. It is thus beneficial to study pulsations in laminar flows, as it avoids the complications of turbulent modeling, for a clear understanding of the cause and growth of the pulsations. Laminar simulations of various experiments in subchannel flows were conducted in this study, with a focus on exploring the evolution of the pulsations. Initial developments of flow in different regions of the subchannels were observed along with their evolution and interactions with each other. Qualitative and quantitative results were analyzed to give a better understanding of the flow pulsations in laminar condition.