Earth's field NMR flow meter: preliminary quantitative measurements

Area of Science:

• Physics
• Chemistry
• Engineering

Background:

• Nuclear Magnetic Resonance (NMR) is a powerful analytical technique.
• Measuring fluid velocity is crucial in various scientific and industrial applications.
• Earth's field NMR (EF NMR) offers a low-field, cost-effective approach to NMR.

Purpose of the Study:

• To demonstrate and validate a quantitative method for measuring fast fluid velocities using EF NMR.
• To adapt a time-of-flight measurement protocol for precise velocity determination.
• To develop a comprehensive flow model for accurate NMR signal interpretation.

Main Methods:

• Utilizing Earth's field NMR (EF NMR) in conjunction with a pre-polarising permanent magnet.
• Implementing a time-of-flight measurement protocol to track fluid movement.
• Measuring NMR signal intensities across a range of flow rates (0-1 m/s) and magnet-detection distances.
• Developing and applying a quantitative flow model to describe the observed NMR signals.

Main Results:

• The EF NMR time-of-flight method provides quantitative measurements of fluid velocities.
• NMR signal intensities correlate predictably with flow rate and spatial separation.
• A parameter-free flow model accurately describes the experimental data, accounting for signal modulation effects.
• The methodology was successfully demonstrated using a metallic pipe.

Conclusions:

• EF NMR combined with pre-polarisation is a viable and quantitative technique for measuring fast fluid velocities.
• The developed flow model enhances the accuracy and reliability of EF NMR velocity measurements.
• This approach offers a sensitive and robust tool for fluid dynamics research and applications.