ANALYSIS OF TEMPERATURE-FIELDS IN ULTRASONIC TRANSDUCERS OF HIGH-POWER

This paper presents the experimental results of heat transfer in an ultrasonic transducer resulting from mechanical and electrical losses during its operation. An approximate theoretical description of the obtained experimental data is given. Experimental investigations of the temperature distribution show that the main sources of the losses are the piezoelectric elements where, besides electrical losses, mechanical losses exist. It appears that mechanical losses in other elements of the transducer are of less importance. The main role of those elements is to spread out the heat from existing sources. Moreover, it is stated that the optimum position of the piezoelectric elements is in the node of the mechanical strain, contrary to the suggestions of other papers. In order to make an in-depth study of the phenomenon, a theoretical analysis of the temperature field in the transducer has been performed. To this end, the boundary element method (BEM) is employed for given experimentally identified heat sources. In previous papers the finite-difference method (FDM) and finite-element method (FEM) were applied. The main advantage of the BEM is the reduction of the number of unknowns as compared with the FDM and FEM. The results of calculations constitute an improvement in the description of the performance of the ultrasonic transducer; moreover, they confirm quantitatively the experimental temperature distribution.