Novel ultrasound based time averaged flow mapping method for die entryvisualization in flow of highly concentrated shear-thinning and shear-thickeningsuspensions

Abstract

In this work a methodology for high-resolution time averaged two-dimensionalflow mapping of converging flows was explored. Flow of non-transparent, highlyconcentrated shear-thinning and shear-thickening suspensions was circulatingthrough the entrance flow adapter with adjustable position of the die entry. Theentrance region was scanned with the distance resolution of 2.7 mm × 1 mm, radialto axial displacement respectively. The time averaged flow map was composedfrom one-dimensional flow profiles measured along the ultrasonic sensor beamusing the ultrasonic pulsed echo Doppler technique. Priory to die entryvisualization an investigation of flow properties was performed using anovel in-line non-invasive measuring technique. The method is based oncombination of the ultrasound velocity profiler velocity monitoring andpressure difference method. The rheological flow properties were derived fromsimultaneous recording and on-line analysis of the velocity profiles across thetube channel and related radial shear stress profiles calculated from thepressure loss along the flow channel. For the first time the entrance flow ofshear-thickening suspension could be visualized. A comparison between the flowof the investigated model suspensions was qualitatively analysed. Thismethod gives an opportunity for time averaged flow mapping of viscoelasticand viscous, non-transparent, multiphase and highly concentrated fluids.