Ultrasonic aerosol agglomeration at low mass loadings
Enhancement of the natural rate of aerosol agglomeration by a high intensity acoustic field has potential application for dust control purposes. Acoustic agglomeration, as measured by reduction in mass loading, is demonstrated on smoke aerosols using a piezo-electric transducer operating at 21 KHz at sound pressure levels (SPL) up to 142dB. At this SPL agglomeration occurs by differential particle entrainment in the sound field or by hydrodynamic attraction due to the relative parallel motion of closely spaced particles, which is increased by acoustic streaming away from the transducer, rather than by acoustically induced turbulence. Aerosol mass loadings are found to reduce roughly exponentially with time. The time constant appears to decrease exponentially with increasing acoustic power at low mass loadings. Large soot flakes up to several centimetres in diameter are formed and remain levitated in the acoustic field. Smaller agglomerates ( 1mm) are not levitated in this way. The amount of water in the ambient air is found to decrease from 40% RH to 4.3%RH in the course of the experiment. Condensation of water may therefore play some role in aerosol formation and agglomeration.
Bibliographic Reference: Paper presented: European Aerosol Conference, Lund (SE), Aug. 30-Sept. 2, 1988
Availability: Available from (1) as Paper EN 34399 ORA
Record Number: 198910135 / Last updated on: 1994-12-01
Original language: en
Available languages: en