Rheology of Particle-Foam Mixture

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Rudolph Kennedy
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1 Aycan Özlem Özarmut Holger Steeb Rheologie Workshop 04. Juni 2014 TP Rheology of Foam 2 1

2 TP Foam in EPB Tunneling [Herrenknecht AG] Improvement of the fluidity and watertightness of excavated soil To prevent the soil from sticking inside of the chamber Easy transportation of excavated soil 3 TP Objectives & Motivation Objectives Experimental research on constitutive properties of face support material Understanding the rheology of foam and particle laden foam Motivation Determination of rheological parameters on realistic scale not possible Investigation of rheological experiments on microscale Replacing realistic support material by model material (shaving foam and glass beads) 4 2

3 TP Micro-scale investigation liquid foam dry glass beads + foam wetted glass beads + foam Micro-scale characterization through image analysis Rheological characterization 5 TP Micro-scale characterization Mean diameter (D) Cell size distribution Shaving foam Silibeads glassbeads Type S 6 3

4 TP Micro-scale characterization Solid glass beads + shaving foam 30% volume of solid glass beads After 2 min. (left) and 57 min. (right) Aging of foams Coalescence Coarsening Drainage 7 TP Micro-scale characterization Wetted glass beads + shaving foam 8 4

5 TP Micro-scale characterization Wetted solid glass beads + shaving foam 64 % volume of wetted solid glass beads 55% volume of solid glass beads After 1 min. (left) and 1 hour (right) 9 TP Types of Rheological Systems MCR 301 (Anton paar GmbH) plate-plate cone-plate concentric cylinder 10 5

6 TP Basic Rheological Tests Flow curve test: Aplication of shear rate: measure stress response Creep test: Application of constant stress: measure deformation response 0scillation test (AS & FS): Apply strain rate oscillations, measure stress response Relaxation test: Apply constant strain, measure decay in modulus Ramp: Increase shear rate, measure stress increase 11 TP Rheological Experiments flow curve oscillation test (AS & FS) relaxation test 12 6

7 TP Rheological Experiments slip effect: disrupts the continuity of flow resulting shear stress are reduced to minimize slip effect: rough plate surfaces -sand paper : P320 (very fine) M Sandpaper 13 TP Rheological characterization Liquid foam- dry particle mixture 14 7

8 TP Flow curve experiment Volume fraction of liquid foam-dry particle mixture: Case 7 Herschel Bulkley Papanastasiou model: Case 1 Fitting parameter from Herschel Bulkley Papanastasiou model: 15 TP Flow curve experiment Herschel-Bulkley Papanastasiou model: 16 8

9 TP Constitutive equation Fluids: (Constitutive relation) Generalized incompressible Fluids: Cauchy stress rate of deformation tensor viscosity unity tensor Measuring constraints of rheometry: The flow is fully described by the continuity equation The fluid flow laminar and isothermal and steady state Its density is constant No slippage on the wall 17 TP Constitutive equation Plane Couette flow or simple shear: fluid x x 2 1 v 1 Velocity gradient: Rate of Deformation tensor: Second invariant of strain tensor : H Viscosity & Shear stress in 3D: 18 9

10 TP Amplitude & Frequancy sweep Amplitude sweep Small amplitude oscillatory sweep (SAOS) Large amplitude oscillatory sweep (LAOS) 19 TP Amplitude sweep (SAOS) Case 7 Case

11 TP Amplitude sweep (SAOS) 21 TP Rheological characterization Liquid foam- wetted particle mixture 22 11

12 TP Flow curve experiment Volume fraction of liquid foam-wetted particle mixture: Case 1 Case 4 Herschel Bulkley Papanastasiou model: 23 TP Amplitude sweep (SAOS) Volume fraction of wetted particles from down to up: 0, 0.09, 0.16, 0.23, 0.28, 0.33, 0.41, 0.47, 0.54, 0.6, 0.64, 0.7 and

13 TP Amplitude sweep (SAOS) Volume fraction of wetted particles : 0, 0.09, 0.23, 0.33, 0.54, 0.6, TP Amplitude sweep (LAOS) The four archetypes of LAOS behavior (Hyun et al., Rheol Acta 2006 ) : (a) strain thinning (b) strain hardening (c) weak strain overshoot (d) strong strain overshoot 26 13

14 TP Relaxation test strain-time and stress-time curve with different material behavior : 27 TP Conclusion Aging of foam (coalescence, coarsening, drainage) in a period of time was observed Foam and particle-foam mixture can be characterised by Herschel-Bulkley Papanastasiou model The yield stress function should be improved Material property depends on composition of particle-foam mixture Over 0.30 volume of particles results in noisy data for flow curve test Linear and non-linear regions of particle-foam mixture were obtained by amplitude sweep test 28 14

15 TP Thank you for your attention!???? 29 15

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