Computational Fluid Dynamics (CFD) Simulations of Aerosol in a U-Shaped Steam Generator Tube

摘要

The Eulerian approach permitted analysis of the gas flow field in the single U-shaped tube. Examination of the computationally derived flow field results revealed flow features consistent with those observed by previous investigators. The Lagrangian approach employing the discrete random walk model for particle dispersion permitted examination of deposition in the U-tube. For the flow conditions analyzed, the dominant removal mechanism was inertial deposition. Inertial deposition due to turbulent fluctuations is probably the least understood and the most difficult mechanism to model and predict. The need to capture physics associated with this phenomena, particularly in the immediate vicinity of walls, required application of a measure to compensate for the deficiencies in the Eddy Impaction Model that arise when used to predict anisotropic turbulent flows. Correcting for anisotropic turbulent velocity fluctuations in the near-wall region provided improved decontamination factor predictions. Computed decontamination factors were consistent with expert elicitation cited in NUREG-1150 for aerosol retention in steam generators.