Design of a Concentrator by an Ultrasonic-Ray Technique

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Abstract
An experimental study is made of the design parameters and the construction of a power ultrasonic concentrator. The technique is that of generating “rays” at the surface of a ferroelectric short cylinder vibrating in its lowest-frequency mode. A plot is made of the surface motion components of the cylinder, and it is found that the predominant components are radial rather than axial. The disseminator shape is determined by the internal ultrasonic-ray configuration that involves direction, reflection, and impingement upon the surface of a processing cavity. The resulting body is, essentially, a truncated ellipsoid of revolution whose outer surface is made of conic segments to facilitate construction. A ferroelectric disk is bonded at the center of the truncated flat surface and is driven by an oscillator and a power amplifier. In operation, a strong sonic field was observed within the cavity whose center is that of one focal point of the ellipsoid of revolution. The other focus determines the normal truncating plane that contains the driving transducer. Two devices are constructed where the number of reflecting planes is varied, and their feasibility as particulate-aerosol generators is disclosed. A simplified version of the device, where three reflecting surfaces are used, is able to form an aerosol cloud made from 0.5 gm of 100-μ aluminum platelets within 3 sec after initiation. The frequency of the devices tested is 46.6 kHz, which coincides with that of a BaTiO3 disk 5.1 cm in diam by 3.8 cm thick, coupled to a large piece of aluminum. A photographic study of the disseminator environment disclosed the formation of unexplained concentric rings about this vibrating device and visible on the surface containing said device.

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