Inhibition of Rayleigh-Bénard convection via oscillatory acceleration

Abstract

The ability to dynamically stabilize Rayleigh-Bénard convection by imposition of sinusoidal acceleration is of interest to groups who design and study thermoacoustic machines, as the introduction of unwanted convection can have deleterious effects on the desired operation and efficiency of the machine. These performance issues, tentatively attributed to convective instability, have been observed both in traveling wave thermoacoustic refrigerators and in pulse tube cryocoolers. This presentation discusses an ongoing experiment designed to determine the vibratory conditions under which a small, rectangular container of statically unstable fluid may be stabilized by vertical vibration, to test the computational methods of R. M. Carbo [J. Acoust. Soc. Am. 135(2), 654–668 (2014)]. Measurement methods developed to determine the onset and inhibition of convection will be discussed. These include the measurement of heat transport employing a feedback thermal control loop and direct optical observation using a lightsheet produced by a laser diode source illuminating seeded particles. Preliminary results in both the static and vibratory conditions will be presented. [Work supported by the ARL Walker Graduate Assistantship, the Office of Naval Research, and ARPA-E.]