Influence of the calorimetric system setup on the output acoustic power measurement results

The problem of measuring an output acoustic power using calorimetric method has been considered in the nonlinear regimes of ultrasound transmitter. The point ultrasound source with sonotrode tip has been driven at different excitation electrical power levels and the influence of the tip position in the different calorimetric systems on the measurement results on output acoustic power is considered. Two calorimetric systems with different volumes of loading liquid (water) and different geometries (having influence on thermodynamical losses) have been used in the experiments. The exponential experimental temperature-time curves have been fitted with theoretical solutions and losses of the systems, output acoustic power and electroacoustic efficiency factor have been found assuming that all ultrasound energy is absorbed in the system. The radiation impedance dependence on complex pressure field distribution in the calorimetric system has been considered measuring the input electrical impedance of loaded and unloaded transmitter.