3.1 Experimental Test Rig
A set of ultrasonic tests of a concentrated liquid–particle system in shear flow has been carried out using a transit-time ultrasonic flow meter. Ca-Bentonite particles (estimated nominal diameter of 60-70 μm, dried density \(\rho_{f}\) = 2500 kg/m3) in water at shear flow of 0-1.5 m/s were studied, for volume fraction up to 1 vol% (or approximately 2.5 wt%). Tests were performed for particle volume fractions ranging from 0 %, in steps of 0.05 vol% until 1.0 vol%.
Figure 2 shows a schematic of the experimental unit used. The test loop is equipped with a mixing tank, a high-level tank, a mechanical mixer, a progressive cavity pump, ultrasonic flow meters, a bellow, valves and a pressure indicator. It consists of a 1 in (24.5 mm) diameter PVC test section and a 2 in (54.78 mm) diameter stainless steel (SS304) test section.