Predicting Cutoff Aerodynamic Diameter and Sharpness of Single Round-Nozzle Impactors with a Finite Impaction Plate Diameter

摘要

This investigation numerically examined the cutoff aerodynamic diameter (da_(50)) and the sharpness (GSD) of the particle collection efficiency curve of impactors with a finite impaction plate diameter. Results revealed that the inertial impactors have a limited cutoff aerodynamic diameter at different air velocities. The extreme value of the cutoff aerodynamic diameter increases with the nozzle diameter (W)/the plate diameter (D_c). The computed da_(50)/D_c values of the impactors increase with W/D_c at various Reynolds numbers (Re) and with the nozzle-to-plate distance (S)/D_c when Re is 100. The value of GSD slightly increases with W/D_c for Re of 10 and 100, although the effect of S/D_c on GSD is not evident at various Res. The particle collection efficiency curve of the impac-tor with a lower Re is less sharp than that with a high Re at various W/D_c and S/D_c values. Statistical equations closely fitted the obtained numerical results for Res of 10-3000. The equations are useful for directly calculating the cutoff aerodynamic diameter and the sharpness of the particle collection efficiency curve for single round-nozzle impactors with a finite impaction D_c.