Inertial Impaction of Aerosol Particles on Cylinders

The inertial impaction of aerosol particles on cylinders was investigated to determine the relationship between the efficiency of impaction and the inertial parameter, the Reynolds number of flow, and the effect of interception. The impaction of sulfuric acid aerosols of nearly uniform size ranging from 0.6 to 1.4 microns diameter, on two platinum wires, 29 and 83 microns diameter, and two tungsten wires, 53 and 106 microns diameter, was measured at several velocities of flow past the wires. Reynolds numbers ranged from 13 to 330. For values of the square root of the inertial parameter Ψ½ below 1.4, the experimental efficiencies of impaction agree with those predicted by Langmuir and Blodgett for potential flow and by Landahl and Herrmann for a Reynolds number of 10. The experimental values are higher than the calculated values for Ψ½ greater than 1.4. The theoretical prediction that a critical value of Ψ½ exists at approximately ¼, below which inertial impaction does not occur, was verified.