Introduc tionIt is very important to knowthe behavior of aerosol particles, particularly in atomic energy facilities because aerosol particles maybe contaminated by radioactivity.Animpactor such as the Andersen sampler is often used for measuring the particle number density distribution in atomic energy facilities.Although a number of theoretical and experimental studies of the impactor have been made3'5>6), there still exist various problems to be considered further regarding the inertial collection of particles2'4).In this study, the effects of the rebound or the re-entrainment on collection of solid particles were investigated by using a round-nozzle impactor.In particular the appearance of a secondary deposit of particles, the so-called "halo", which greatly influence collection efficiency2>, was studied by observing collected particle number density. Experiment
The pressure recovery of supersonic flow at very low density was studied in a vane-island type diffuser for gas centrifuge. A tester of diffuser with a rapidly rotating cylinder was used in experiments. Wall static pressures were measured at many points in the diffuser to observe the static pressure distribution. The change of pressure distribution with back pressure and the effect of flow rate were investigated. Pressure distribution showed that the pressure recovery occurred in the converging section. The pressure ratio increased linearly with the back pressure in this experimental range and the effect of flow rate was not observed. A numerical analysis of the pressure recovery in the channel section of the diffuser was made by applying the finite difference method to the slender-channel equations. The pressure distribution obtained in experiments could be explained as a result of supersonic compression with reverse flow.
The pressure recovery of supersonic flow at very low density was studied in a vane-island type diffuser for gas centrifuge. A tester of diffuser with a rapidly rotating cylinder was used in experiments. Wall static pressures were measured at many points in the diffuser to observe the static pressure distribution. The change of pressure distribution with back pressure and the effect of flow rate were investigated. Pressure distribution showed that the pressure recovery occurred in the converging section. The pressure ratio increased linearly with the back pressure in this experimental range and the effect of flow rate was not observed. A numerical analysis of the pressure recovery in the channel section of the diffuser was made by applying the finite difference method to the slender-channel equations. The pressure distribution obtained in experiments could be explained as a result of supersonic compression with reverse flow.
