MICRON AND SUBMICRON AEROSOL SIZING WITH A STANDARD PHASE-DOPPLER ANEMOMETER

In this paper the extended application range of the standard phase-Dop pler anemometer (PDA) to particle diameters below the commonly accepte d lower limit of about 5-10 mu m is described. The problems that accom pany measurements on smaller particles are small scattering cross-sect ions and ambiguous relations between the measured phase difference Del ta Phi and the particle diameter d. A simple, but flexible optical set -up for the transmitting part of a standard PDA system, and a numerica l algorithm, which allows careful data evaluation from ambiguous Delta Phi(d) relations, help to manage these problems. Measurements on aque ous suspensions of micron and sub-micron sized dielectric and metalic monospheres, as well as on polydisperse aerosols, are presented and ev aluated by means of the proposed algorithm. (C) 1998 Elsevier Science Ltd. All rights reserved.