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Inline ultrasonic rheometry by pulsed Doppler.
David M Pfund1, Margaret S Greenwood, Judith A Bamberger
1Pacific Northwest National Laboratory, Battelle Boulevard, MS K7-15, Richland, WA 99352, USA. david.pfund@pnl.gov <david.pfund@pnl.gov>
Ultrasonics
|July 1, 2006
Summary
This study introduces a non-invasive method to measure non-Newtonian fluid viscosity using pulsed ultrasonic Doppler velocimetry. This technique enables real-time monitoring of fluid properties in pipe flow, crucial for industrial process control.
Area of Science:
- Fluid Mechanics
- Rheology
- Ultrasonic Measurement Techniques
Background:
- Accurate viscosity measurement is critical for non-Newtonian fluids in industrial processes.
- Traditional methods can be invasive or unsuitable for real-time monitoring.
- Understanding fluid behavior in pipe flow requires detailed velocity profile data.
Purpose of the Study:
- To present a non-invasive method for determining the viscosity of non-Newtonian fluids.
- To validate the technique using laminar pipe flow and a shear-thinning gel.
- To discuss the operational parameters and limitations of the Doppler-based instrument.
Main Methods:
- Utilizing a pulsed ultrasonic Doppler velocimeter to measure the flow profile.
- Determining the pressure drop along a straight pipe section.
- Calculating viscosity based on flow profile and pressure drop data.
Main Results:
- Successfully demonstrated non-invasive viscosity determination for a shear-thinning gel.
- Presented rheograms illustrating the fluid's shear-thinning behavior.
- Identified velocity gradient broadening as a key limitation near pipe walls.
Conclusions:
- The pulsed ultrasonic Doppler velocimeter offers a viable non-invasive approach for real-time viscosity measurements.
- The method is suitable for monitoring and control applications in pipe flow.
- Limitations, particularly for strongly shear-thinning fluids, require careful consideration of instrument parameters.