Ultrasonic measurements
Person in charge: Dipl.-Ing. Leon Knüpfer
Project leader: Dr.-Ing. Sascha Heitkam
Duration: 07/2020 – 01/2023
Funding: AiF/IGF
The investigation of dynamics and composition of aqueous foams in three dimensional geometries requires specialized measurement techniques which yield information on the regions beyond the opaque surface of a foam.
In collaboration with the Chair of Measurement and Sensor Systems we investigate the applicability of ultrasonic systems for characterization of foam and froth. Using low-frequency ultrasound in the range between 40 kHz and 200 kHz, a penetration depth of several centimeters can be achieved. A sound wave will be reflected on the liquid fluid interfaces inside the foam. By analyzing the backscattered part of an ultrasonic signal sent inside a foam, information on the local foam composition can be derived.
By applying ultrasound Doppler velocimetry (UDV) the velocity of a flowing foam can be obtained. For that, the frequency shift of a sound wave which is reflected on a scatterer moving with the foam is measured. Using this information and the time-of-flight between reflector and ultrasonic transducer, the local velocity in the bulk of a foam can be determined. Flowing foams play an important role in froth flotation and a wide range of other industrial processes.
Publications
Nauber et al., Ultrasonic measurements of the bulk flow field in foams, Phys. Rev. E 97, 2018, 10.1103/PhysRevE.97.013113
Emmerich et al., Linear, spatio-temporally resolved ultrasound measurement of the liquid fraction distribution in froth, Technisches Messen 88 (9), 2021, 10.1515/teme-2021-0047
Summary of the final report - For receiving the full report please contact Sascha Heitkam.