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Ultrasonic power measurements in the nonlinear regime using calorimetry method

In this work output acoustic power radiated from an ultrasound source has been measured assuming that all radiated ultrasound energy has been converted into heat in the small volume of the liquid. The sonotrode tip has been assumed as a point source and its output acoustic power can be measured at the linear regime in the free far field, measuring the dynamic pressure. In the nonlinear regime when cavitation is present, the better way is measuring total heat energy delivered by the ultrasonic device into volume of liquid in the specified time. The temperature in the calorimetric system when the source is on, increases exponentially depending on the total specific heat capacity and heat losses in the system. The losses in the non-ideal calorimeter effecting the results for unknown acoustic power can be estimated using well-known power of the equivalent heater source which power is approximately same as the acoustic power of unknown ultrasound device. Calorimeters with different geometry have been characterized experimetally and theoretically and unknown output acoustic power has been found for few different measurement setups. The influence of two different temperature sensors with different resolution on measurement results has also been considered.

ultrasound point source; output ultrasonic power; non-ideal calorimetric system; equivalent heater source

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