Investigation of acoustic aerosol agglomeration mechanisms under traveling-wave condition. Period covered: 1 July-30 September 1980.

Experimental investigations of acoustically induced turbulence and shock waves in a traveling-wave tube are performed with and without the introduction of an air flow through the system. Frequency (f) and intensity (l) effects of the acoustic field are studied using a hot-film anemometer and FFT data processing unit. The effect of the acoustically induced turbulence on a laminar flow is also investigated. Sampled data are first conditioned, then processed to estimate the characteristics of turbulence. It is found that for sound pressure level 158 dB turbulence appears. Furthermore, at a slightly higher level (approx. 160 dB) shock waves appear over the range of all frequency. The turbulent spectrum F and the wave number k are found to satisfy a power law. Throughout the whole measuring range of f and l, the rate of energy dissipation per unit mass epsilon is estimated to be 10 exp 6 to 10 exp 7 cm exp 2 /s exp 3. It is also found that superimposing a laminar air stream through the tube will suppress the turbulence. (from author's abstract)