| Acoustic coagulations in intense sound fields were studied both experimentally and theoretically. These studies were conducted under the traveling-wave conditions with the sonic intensity levels ranging from 145 to 1556 dB (re 10('-16) watt/cm('2)) and frequencies from 600 to 3000 Hz. The aerosols used in these studies were the ammonium chloride with mass concentrations of 2-20 gm/cm('3) and sizes from 0.06 to 35 (mu)m as measured by using Berner's impactors. Optical attenuation technique was also used to measure the variations of the total surface area of the particles under various circumstances.; It is found that the experimental results always show a bimodal mass distribution for the acoustically agglomerated particles. Furthermore, the agglomeration increases with the sonic frequency, the intensity, the particle size and the mass loading.; To furnish a theoretical basis, the acoustic coagulation kernels are numerically evaluated. The effect of acoustic parameters (intensity, frequency) and aerosol properties (size, number concentration and polydispersity) are studied. A new numerical scheme has been developed, tested and used to calculate the mass distribution of the acoustically agglomerated particles.; A comparison of the experiment with theory shows that the orthokinetic interaction is the dominant mechanism under all the experimental conditions in this study. It is also found that when the total number of coarse particles (collectors) is small, the measured mass distributions of the agglomerated particles are in good agreement with the numerical calculation. Once the number of collectors becomes large, the experimental data is lower than that as calculated by the theory. |
