ASA 125th Meeting Ottawa 1993 May

4aPA4. Bubble dynamics in low gravity and related experiments on Earth.

Philip L. Marston

Dept. of Phys., Washington State Univ., Pullman, WA 99164-2814

Eugene H. Trinh

Jet Propulsion Lab., Pasadena, CA 91109

A dual-frequency acoustic levitator containing water was developed for studying bubble and drop dynamics in low gravity. It was flown on USML-1 where it was used in NASA's Glovebox facility. High-frequency (21- or 63-kHz) ultrasonic waves were modulated by low frequencies to excite shape oscillations on bubbles and oil drops ultrasonically trapped in the water. Bubble diameters were typically close to 1 cm and the low gravity alters biases present in related experiments in 1 g. Other observations concerned the agglomeration or coalescence of bubbles in response to acoustic Bjerknes forces, the response of bubbles to surfactant injection, oscillations of bubbles coated by oil, and ultrasonic cavitation. Observations suggest that shape oscillations tend to shift the coated bubble away from the oil--water interface of the coating. Supporting experiments in 1-g extending earlier results [Asaki et al., J. Acoust. Soc. Am. 93, 706--713 (1993)] will also be examined. [Work supported by NASA and by ONR.]