Advancing magnetic resonance measurements of mass transport

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The proposed research aims to improve magnetic resonance imaging (MRI) methods for use in materials science. MRI has been an astonishingly successful clinical technique because it causes no harm to the patient (is non-invasive) and because it can visualise the inside of opaque objects. These same advantages make MRI a useful technique for the study of materials. MRI is a very flexible measurement method, which can be used to map a variety of material properties including temperature, pH or chemical potential in three dimensions. We are developing new methods to map motion in gas and liquid samples. Our MRI techniques are able to measure velocity and the fluctuations of velocity in fast, turbulent gas flows, which are important for their application in everything from wind turbines to jet engines. The first strand of this proposed research will address the measurement of velocity in flows approaching the speed of sound to improve our understanding of gases in this regime. The new measurements are only now possible using a combination of hardware and calibration techniques developed in our earlier work. We are also improving MRI methods for use in mixtures of gases and liquids, such as foams, which are critical in a variety of applications including water remediation and food processing. The second strand of the proposed research is the development of independent measurements of the gas and liquid velocities in foams, using a new magnet design, which allows the foams (and other multi-phase flows) to be measured at any orientation between horizontal and vertical. The two strands of the proposed research are connected by the use and improvement of materials MRI techniques we have developed at the UNB MRI Centre, which use short, constant times to encode the MRI signal and shaped pulses of radiofrequency excitation to select the appropriate section of the flowing fluids for measurement.