ASA 128th Meeting - Austin, Texas - 1994 Nov 28 .. Dec 02

3aPAb10. Experimental study of streaming in acoustic resonators.

Joseph C. Jankovsky

R. Glynn Holt

Robert E. Apfel

Dept. of Mech. Eng., Yale Univ., New Haven, CT 06520-8286

Anomalous rotations of solid and liquid drops have been observed in resonant chambers in both 1g and in the microgravity environment of space in the Drop Physics Module (DPM) aboard the United States Microgravity Laboratory (USML-1) mission in 1992. The observed torques are produced by acoustic streaming, typically in the nondegenerate plane where rotations are undesired, and have been attributed to an imbalance in the paired driver amplitudes. To quantify the torque exerted on the inclusion, measurements were made using suspended and levitated spherical samples with single and paired driver configurations. Experiments were conducted in both degenerate and nondegenerate planes to study the effects of orthogonal coupling. Absorption effects of active and passive drivers are presented, along with asymmetrical driver configurations. The results will be used to control and eliminate unwanted tumbling rotations in the USML-2 DPM experiments to be flown in 1995. [Work supported by NASA through JPL Contract No. 958722.]