VISUALIZATION OF FLOW-FIELDS AND NUMERICAL-CALCULATION OF COLLECTION EFFICIENCY IN LOW-PRESSURE IMPACTOR

Flow fields of nitrogen (N-2) and argon (Ar) gases in a low pressure i mpactor are visualized by using a Laser Induced Fluorescence (LIF) tec hnique of iodine molecules under typical MLIS (Molecular Laser Isotope Separation) operating conditions for uranium hexafluoride (UF6). The flow fields with different pressure ratios (downstream pressure/upstre am pressure) and nozzle-to-plate distance are examined. It is shown th at various shock waves exist in the low pressure impactor. The axisymm etric Euler equation is solved by using the Harten-Yee TVD method. The calculated shapes and locations of shock agree R-ell with experimenta l data obtained by LIF. The calculated solutions compared with those p reviously calculated, however, a remarkable difference is observed bet ween these two calculated results. With the aid of calculated flow fie lds, the collection efficiency is determined by tracking the particle trajectories. The diameter of 50% collection is found to be dependent on the pressure ratios and nozzle-to-plate distance. It is shown that the dependency of diameter of 50% collection on these parameters is di fferent between this study and previously calculated one.