Noninvasive Monitoring of Temperature Distribution in Liquids with Ultrasound by Locally Resolved Measurement of Sound Velocity

摘要

A new method to measure sound velocity and distance simultaneously and locally resolved is applied in media with continuously changing properties. Instead of using reflectors at known positions the echoes of moving scattering particles are analysed to determine the focus position of an annular array. Systematic deviation between measurements and sound field simulations show that sound propagation has to be described with a modified wave equation. A new approach determining Green's functions for a half space with continuously changing properties is presented. It combines the high frequency approximation with an integral transform method.