Measurements of spray system dynamics with NMR

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University of New Brunswick


Spray systems present unique challenges for fluid mechanics research due to their complex dynamics. Techniques employing synchrotron X-rays and Magnetic Resonance Imaging (MRI) are promising measurement avenues for non-invasive studies of opaque or enclosed sprays. Previous MRI studies of sprays employed sophisticated pulse sequences possible only with an MRI scanner. In this work, the potential of simple bulk MR techniques, Pulsed-Field-Gradient (PFG), Time-Of-Fight (TOF), and Dynamic Magnetic Resonance Scattering (DMRS) are evaluated to investigate spray dynamics in three distinct regions. The PFG measurements of mechanical dispersion using MR are the first of their kind to our knowledge, yielding dispersion coefficients in the range of 10-4 – 10-3 m2/s. Velocity measurements successfully detected velocities surpassing 30 m/s near the nozzle, with flow slowing down to several m/s downstream. These techniques show potential for investigating spray dynamics and simple gradient requirements make them suitable for portable MR applications and in-situ measurements.