NUMERICAL STUDY OF PARTICLE TRANSPORT AND DEPOSITION IN A HORIZONTAL CHANNEL USING A LAGRANGIAN-BASED MODELLING APPROACH

摘要

Texas A&M University is participating in the U.S. Department of Energy (DOE) Office of Nuclear Energy's Versatile Test Reactor (VTR) program to develop instrumentation and tools for a proposed fast spectrum test reactor. Our research project aims to develop and implement techniques to quantify the transport and deposition of fission products in the primary system of Gas Fast Reactors (GFRs) and ultimately in the reactor confinement. Developed techniques will be performed and tested in the NGNP Reactor Building experimental facility, which was previously 1/28 downscaled from General Atomics 350 MWth and built to study the reactor building responses to depressurization accidents. Prior to applying the techniques to the scaled facility, it is essential to verify and validate the performance of developing techniques using numerical simulations and quantify their associated uncertainties. This manuscript presents our numerical study of particle transport and deposition in an experimental channel. The channel has three test sections, each has 3-inch square cross-section, 24 inches in length for a combined total length of 72 inches. The experimental facility is built using transparent materials, allowing the applications of non-intrusive, laser-based measurement techniques, such as Particle Image Velocimetry (PIV) and Particle Tracking Velocimetry (PTV). Details of the experimental setup, measurement techniques, and results of flow field characteristics and particle transports in the channel will be presented in an accompanied manuscript. The simulation domain is built upon the geometrical dimensions of the experimental facility, while upstream flow characteristics of the square channel obtained by PIV measurements are used as boundary conditions. State-of-the-art Lagrangian approach with random walk model is employed to investigate behaviors of surrogate particles within the square channel, coupled with computational fluid dynamics (CFD) model. While the main stream in the channel is solved by Eulerian turbulent model, motion of particles is tracked in Lagrangian framework. It is assumed that well-mixed air-particle mixture at a constant temperature is injected into the horizontal channel. Drag force, gravity force and turbophoresis force are adapted on this simulation and their competition are investigated. Comparisons and validations of simulations and measurements on the flow fields downstream of the channel and characteristics of particle transports and depositions within the square channel will be systematically investigated. Experimental and numerical uncertainties will be quantified using the accepted standard approaches.