Acoustic particle agglomeration due to hydrodynamic interaction between monodisperse aerosols

The experimental verification of the theory on the hydrodynamic collisions in acoustic agglomeration is reported. Measurements are carried out on the time-dependent particle size distribution function using relatively monodisperse aerosols. These data are then used to determine the acoustic agglomeration constant which agrees well with the theoretical prediction. Two different experimental acoustic sources are used: one is a low frequency electromagnetic speaker and the other is a high frequency siren. Results show that acoustic agglomeration by hydrodynamic collision is important for particles radii larger than 0.5 μm in the audible frequency region (less than 10 k Hz). It is found that the acoustic agglomeration of these large particles is relatively insensitive to the frequency change, in contrast to the orthokinetic interaction whose effectiveness is sensitively dependent on the acoustic frequency.