EXPERIMENTAL AND NUMERICAL INVESTIGATION OF FLOW PHENOMENA IN A VERTICAL T-JUNCTION CONFIGURATION

摘要

Turbulent and stratified mixing flows can cause thermal fatigue in nuclear power plant piping systems. In order to diminish the investigation effort of thermal mixing flow phenomena, a geometrically similar isothermal Mixed Fluid Interaction (MFI) mixing tee using a sodium chloride solution to model the cold heavy branch pipe fluid is built. The purpose of the MFI experiments is to predict the flow phenomena in the vertical thermal mixing Fluid Structure Interaction (FSI) T-junction configuration at the University of Stuttgart. Due to limited optical accessibility of the FSI facility a numerical similarity comparison of the flow phenomena occurring in both experimental setups (MFI/FSI) is essential. Thus. Large Eddy Simulations are carried out which are experimentally validated by applying the Particle Image Velocimetry and Planar Laser Induced Fluorescence measurement techniques and as well as benchmark data. The similarity investigation confirms the usage of three characterizing parameters for the adaption of relevant physical boundary conditions to the FSI setup (branch pipe Reynolds number (Re_b), mixing Richardson number (Ri) and momentum ratio (M_R)). Thereby, the evidenced similarity ensures the utilization of the cold mixing experimental setup for the visual prediction of flow patterns occurring in the hot mixing FSI facility.