engleski

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

The problem of measuring an output acoustic power using calorimetry method has been considered in the linear and nonlinear regimes of transmitter working. The transmitter with sonotrode tip has been driven at different excitation power levels and the influence of sonotrode tip position in the different calorimetric systems on the measurement results 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 and time constants, losses, output acoustic power and electroacoustic efficiency factor have been found assuming that all ultrasound energy is absorbed in the system. The pressure field in the box is complicated and radiation impedance (radiated power) depends on the position in the complex ultrasound field where the point source is located. In the nonlinear regime of working strong cavitation activity occur with oscillating bubles in the front of vibrating tips and derived acoustic power is decreased because the tip is only partially radiating due to radiation impedance variations. The bubble are collapsing and not only acoustic energy but heat energy is also generated. The electroacustic efficiency factor has been compared with equivalent circuit approach where parameters of transmitter have been found for unloaded and loaded transmitter in configurations for calorimetric method.

calorimetric method; linear and nonlinear regime of transmitter working; electro- acoustic efficiency factor

nije evidentirano