Abstract
A mixture of polyborosiloxane and silicon carbide abrasive has been agitated using an ultrasonic system. The passage of the ultrasonic wave through this mixture resulted in an increase in temperature due to conversion of energy from the ultrasonic wave into heat. This investigation was initially concerned with the calculation of the heat-generation term, from a knowledge of the attenuation of the acoustic wave. The second stage of the analysis involved the solution of the relevant transient heat-transfer equations for conduction and convection with internal heat generation. The solution to these equations was obtained using a numerical technique.
Temperatures at various positions within the system were measured using suitable equipment. These experimental data were compared against the results of the calculation and it was found that significant discrepancies existed between the two sets of results when the analysis considered heat generation as a sole function of wave attenuation.
In an attempt to improve the correlation between calculated and measured temperatures the analysis was developed to include a heat-generation term acting at the interface between the sonotrode and the transmission medium. Such heat generation would be produced by frictional heating at the interface, and this would be associated with poor coupling between the acoustic source and the medium. It was found that the correlation between calculated and measured temperatures improved greatly on adoption of the frictional heating analysis, which leads to the suggestion that heating within the medium is a function of both ultrasonic attenuation and frictional heating. For the conditions specified the latter appears to have a dominant role.
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