Laser Settling Velocimeter: Aerodynamic Size Measurements on Large Particles

Abstract

A Laser Settling Velocimeter (LSV) has been developed for the measurement of large particle aerodynamic diameters and has been applied in the range 10—20 μm. A vertical settling tube is illuminated along the axis by a 5 mW He—Ne laser beam to permit manual timing of falling particles. Measurements on DOP particles from a vibrating orifice generator agree with diameters calculated from the generator operating parameters to within 0.3% when the slip correction is included. The LSV is a simple instrument which is particularly useful for the direct determination of the aerodynamic diameters of solid particles, irrespective of density or shape.