Measurement of Flow and Structures through an Acoustic Multimode Waveguide based on Time Reversal

• Applicants: Professor Dr.-Ing. Jürgen W. Czarske; Dr.-Ing. Sven Eckert
• Subject Area: Measurement Systems
• Term: since 2018
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 411799900

Ultrasound-based measurements are essential for fundamental research in magnetohydrodynam-ics, as they allow spatially and temporally highly resolved flow and structure imaging in opaque liq-uids. Due to the temperature sensitivity of the ultrasound transducers, experiments are often limited to room temperature. An approach for in-process measurements in hot melts is to separate the ul-trasound transducers from the hot fluid through an acoustic waveguide. Up to now, single-mode waveguides are used that exhibit a strong acoustical damping, which leads to a low signal quality. Furthermore, they are mechanically complex and do not allow for direct imaging. This research proposal aims for investigating methods for ultrasound-based imaging through acous-tical multimode waveguides that enable imaging with mechanical scanning. However, due to the complex sound propagation, a scrambling occurs, which has to be compensated for quantitative measurements. This project focuses on the system engineering aspects of ultrasound imaging through multimode waveguides. The Time Reversal Virtual Array is investigated as method for compensating complex sound propagation, enabling novel ultrasound imaging with high spatiotem-poral resolutions. Strategies for system identification without access to the measurement volume under laboratory (ex situ) and field conditions (in situ) will be investigated. The imaging of structures and flows should be comprehensively characterized and qualified for the use in hot melts. This proposal investigates the possibilities and limitations of the novel measurement system in order to save energy and to improve the quality of processes.

• DFG Programme: Research Grants