How UVP-DUO Helps to Apply Ultrasonic Spinning Rheometry to Complex Fluids

8 July 2024 by
How UVP-DUO Helps to Apply Ultrasonic Spinning Rheometry to Complex Fluids
Met-Flow SA

Summary of the Experiment:

The study explored the application of Ultrasonic Spinning Rheometry (USR) to various complex fluids, including silicon oil, polymer solutions, clay dispersion, and multi-phase fluids like water-oil mixtures. The objective was to measure the rheological properties of these fluids using USR, which integrates ultrasonic velocity profiling (UVP) with rheometry. This method aims to address the limitations of conventional rheometers, particularly in dealing with non-Newtonian fluids and multi-phase systems.

UVP-DUO Usage:

The UVP-DUO-MX (Met-Flow S.A., Switzerland) was employed to capture detailed velocity profiles within the fluids. Key setup parameters for the UVP-DUO included:

- Ultrasonic Frequency: 4 MHz

- Transducer Diameter: 5 mm

- Spatial Resolution: 0.1 mm

- Temporal Resolution: 10 ms

- Measurement Volume: Disk-like, suitable for capturing azimuthal velocity components

The UVP-DUO was mounted at a specific distance from the center of an acrylic cylindrical container filled with the test fluid. This setup allowed for precise measurement of instantaneous velocity distributions under controlled oscillatory shear conditions.

Results of the Experiment and How UVP-DUO Contributed:

The experiments provided significant insights into the rheological properties of various complex fluids:

1. Silicon Oil (500 cSt):

   - The velocity profiles showed consistent phase lag from the cylinder wall, indicating Newtonian behavior.

   - Rheological properties matched catalog values, validating the accuracy of USR.

2. Polymer Solutions (CMC and PAM):

   - Results indicated shear-thinning behavior with decreasing viscosity at higher shear rates.

   - The viscoelastic nature was confirmed by phase lag measurements.

3. Clay Dispersion (Montmorillonite):

   - Demonstrated thixotropic characteristics, with a distinct change in viscosity at the gel-sol interface.

   - Spatial distribution of rheological properties was accurately captured, showing the interaction between dispersed particles.

4. Water-Oil Two-Phase Fluid:

   - Evaluated viscosity changes over time due to the separation of water and oil phases.

   - The results showed an increase in effective viscosity due to non-equilibrium deformation of droplets.

5. Air-Oil Two-Phase Fluid:

   - Assessed viscoelasticity of bubbles deforming under oscillatory shear.

   - The elastic contributions were identified, indicating periodic deformation and restoration of bubbles.

The UVP-DUO's high-resolution velocity measurements were crucial for accurately determining shear rates and viscoelastic properties. This study demonstrated the effectiveness of USR combined with UVP-DUO in measuring the complex rheological behavior of various fluids, providing valuable data for both scientific research and industrial applications. The findings underscore the potential of UVP-DUO to advance rheometry techniques and enhance the understanding of complex fluid dynamics.

Read the full paper in our Digital Library here.

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