ACOUSTIC FIELD INTERACTION WITH A BOILING SYSTEM UNDER TERRESTRIAL GRAVITY AND MICROGRAVITY

Pool boiling experiments from a platinum wire heater in FC-72 liquid w ere conducted under terrestrial and microgravity conditions, both with and without the presence of a high-intensity acoustic standing wave w ithin the fluid. The purpose of this research was to study the interac tion between an acoustic field and a pool boiling system in normal gra vity and microgravity. The absence of buoyancy in microgravity complic ates the process of boiling. The acoustic force on a vapor bubble gene rated from a heated wire in a standing wave was shown to be able to pl ay the role of buoyancy in microgravity. The microgravity environment was achieved with 0.6 and 2.1-s drop towers. The sound was transmitted through the fluid medium by means of a half wavelength sonic transduc er driven at 10.18 kHz. At high enough acoustic pressure amplitudes ca vitation and streaming began playing an important role in vapor bubble dynamics and heat transfer. Several different fixed heat fluxes were chosen for the microgravity experiment and the effects of acoustics on the surface temperature of the heater were recorded and the vapor bub ble movement was filmed. Video images of the pool boiling processes an d heat transfer data are presented. (C) 1998 Acoustical Society of Ame rica. [S0001-4966(98)04810-3].