Fluctuations in Flows by NMR

9404778福岛将探讨核磁共振成像（NMRI）用于测量两相流波动参数的潜在用途。两相参数包括固液速度波动、混合物密度波动、扩散系数和速度相互关系。关键问题是减少每次成像所需的时间。另一个目标是发展必要的技术，以解释由核磁共振成像确定的波动及其相关性，并确定该方法的局限性。目前的光学方法不适用于大多数不透明的液-固混合体系，特别是在工业应用中。洛夫莱斯研究所将提供减少磁体涡流的新设备，这是该项目的主要硬件要求。通过控制涡流，初步试验中单个测量的梯度切换速度提高了三个数量级。预计在0.05秒内完成64X64网格的二维速度成像，这将在质量上优于以往的结果，并且足够快，可以用于相对低雷诺数的湍流中的速度波动。实验将在一个相对简单的几何结构中进行，其中有两相波动参数的参考数据。该预算包括与西雅图华盛顿大学合作的教育类费用。先进核磁共振成像技术作为一种通用的无损检测技术，在化工制造和其他加工行业的多相流系统控制中有着广泛的应用。如果成功，本项目将证明将NMRI用于大量两相流测量的可行性，对推进多相流的科学（新仪器，不透明多相系统的参考数据集）和技术（非侵入式原位传感器）具有重要影响。＊＊＊

9404778 Fukushima The potential use of nuclear magnetic resonance imaging (NMRI) for measuring fluctuating parameters in two-phase flow will be explored. The two-phase parameters include solids and liquid velocity fluctuations, mixture density fluctuations, diffusion coefficients and velocity cross-correlations. The key issue is the reduction of the time necessary for each imaging. Other objective is developing techniques necessary to interpret the fluctuations and their correlations determined by NMRI, and to define the limits of the method. Current optical methods are not suitable for most liquid-solid mixture systems which are opaque, particularly in industrial applications. The Lovelace Institutes will provide new equipment for the reduction of eddy currents in the magnets, which is the main hardware requirement of the project. The gradient switching speed for individual measurements in the preliminary tests has been increased by three orders of magnitude by controlling the eddy currents. It is expected that velocity imaging in a two-dimensional domain could be performed in 0.05 seconds for a 64X64 mesh, which would be qualitatively superior to previous results and would be sufficiently fast to be used for velocity fluctuations in turbulent flows with relatively low Reynolds number. The experiments will be performed in a relatively simple geometry for which there are reference data on two-phase fluctuating parameters. The budget covers educational type of expenses, in collaboration with the University of Washington in Seattle. Advanced NMRI has application as a versatile non-destructive measuring technique to control multiphase flow systems in chemical manufacturing and other processing industries. If successful, the present project will demonstrate the feasibility of using NMRI to a large group of two-phase flow measurements, with important impact on advancing the science (new instrumentation, reference sets of data for opaque multiphase system s) and technology (nonintrusive in-situ sensors) of multiphase flow. ***