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Experimental Investigation of Dynamic Stabilization of the Rayleigh-Bnard Instability by Acceleration Modulation

出版	Pennsylvania State University, 2017
URL	http://books.google.com.hk/books?id=b8xsswEACAAJ&hl=&source=gbs_api

註釋This dissertation presents the results of an experimental investigation of the parametric stabilization of Rayleigh-Bnard convection through the imposition of vibration. It has been theorized for many years that vibration could be employed to suppress natural convection, in an analogous manner to the Kapitza pendulum. The ability to dynamically stabilize Rayleigh-Bnard convection using acceleration modulation is of interest to groups who design and study thermoacoustic machines, as the introduction of parasitic convection can have deleterious effects on the desired operation and efficiency of the device. These performance issues caused by suspected convective instability have been seen both in traveling wave thermoacoustic refrigerators and in cryogenic pulse tube chillers. This dissertation reports the results of an experiment intended to determine the vibratory, fluidic, and geometric conditions under which a small, rectangular container of statically unstable fluid may be stabilized by vertical vibration, incorporating the computational methods of R.M. Carbo [J. Acoust. Soc. Am. 135(2), 654668 (2014)]. Measurements are obtained using a large-displacement kinematic shaker of an original design with the convecting gas characterized using both thermal transport measurements and flow visualization employing tracer particles illuminated by a diode laser light sheet phase-locked to the shaker. These experiments are believed to be the first demonstrating the suppression of convection through vibration in rectangular containers of macroscopic scale.