Rheological properties of wet foams generated from viscous pseudoplastic fluids

Effects of flow constriction on foamed viscous shear-thinning fluids downstream of a continuous multi rotor-stator foaming device

“…Increasing N over this range led to a modest increase in pressure drop across the constriction which can be explained by the finer foams generated (i.e. more complex thin liquid film network) which dissipate more energy in flow (Jabarkhyl et al, 2020b). Flow through the constriction causes, in all cases, a considerable rise in the mean bubble size, as shown in Fig.…”

“…The materials and methods used are based on our recent related work which studied the continuous production of foams from complex viscous shear-thinning fluids in a multi rotor-stator device and their rheological properties (Jabarkhyl et al, 2020a, Jabarkhyl et al, 2020b. We used five model complex non-Newtonian fluid formulations of shear-thinning rheology consisting of a mixture of polyglycerol fatty acid ester (PGE 55), xanthan gum (XG), caster sugar and sodium azide, denoted MF1, MF2, MF3, MF4 and MF5, whose composition and physical properties are summarised in Table 1.…”

“…Foams of different textures were obtained by using combinations of liquid and air flowrates within the range 2.5 -5.0 L h -1 and 0.1 -12.5 L hr -1 , respectively. Further details of the protocols adopted for the preparation of the model fluids and foams can be found in our previous work (Jabarkhyl et al, 2020a, Jabarkhyl et al, 2020b.…”

“…The measurement time was kept short to avoid foam drainage effects. More details on the rheometry procedures adopted can be found in our previous work (Jabarkhyl et al, 2020b).…”

“…However, there are conflicting reports on the effects of static pressure and residence time which hitherto remain unclear and hence need further investigation (Mary et al, 2013, Balerin et al, 2007, Müller-Fischer and Windhab, 2005 Recently, we investigated the continuous foaming of viscous non-Newtonian shear-thinning model food liquids in a pilot-scale multi rotor-stator high-shear device (Jabarkhyl et al, 2020a), and studied the effects of processing parameters including rotor speed, gas-liquid ratio, surfactant and xanthan gum concentration. Furthermore, we studied the steady-shear as well as viscoelastic rheological properties of the various wet foams thus generated (Jabarkhyl et al, 2020b). The foams exhibited high static stability and resistance to steady shear with no bubble breakage observed when the foams were sheared between parallel-plates on a rheometer.…”