MODELING OF HEAT-GENERATION AND RESULTANT TEMPERATURE DISTRIBUTION DUE TO THE PASSAGE OF AN ULTRASONIC WAVE THROUGH A MIXTURE OF POLYBOROSILOXANE AND SILICON-CARBIDE

A mixture of polyborosiloxane and silicon carbide abrasive has been ag itated using an ultrasonic system. The passage of the ultrasonic wave through this mixture resulted in an increase in temperature due to con version of energy from the ultrasonic wave into heat. This investigati on was initially concerned with the calculation of the heat-generation term, from a knowledge of the attenuation of the acoustic wave. The s econd stage of the analysis involved the solution of the relevant tran sient heat-transfer equations for conduction and convection with inter nal heat generation. The solution to these equations was obtained usin g 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 result s when the analysis considered heat generation as a sole function of w ave attenuation. In an attempt to improve the correlation between calc ulated 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 wit h poor coupling between the acoustic source and the medium. It was fou nd that the correlation between calculated and measured temperatures i mproved greatly on adoption of the frictional heating analysis, which leads to the suggestion that heating within the medium is a function o f both ultrasonic attenuation and frictional heating. For the conditio ns specified the latter appears to have a dominant role.