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首页> 外文期刊>Experiments in Fluids: Experimental Methods and Their Applications to Fluid Flow >Velocity measurements of flow through a step stenosis using Magnetic Resonance Imaging
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Velocity measurements of flow through a step stenosis using Magnetic Resonance Imaging

机译：使用磁共振成像测量通过狭窄段的流速

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Magnetic resonance imaging (MRI) is a versatile noninvasive tool for achieving full-field quantitative visualization of complex fluid flows. The MRI signal results from the interaction of radio-frequency (RF) pulses with nuclear spins exposed to a strong static magnetic field. The two main techniques of MRI velocimetry are time-of-flight and phase contrast techniques. Time-of- flight techniques involve tagging and tracking a material volume of fluid, whereas phase contrast techniques use magnetic field gradients to encode velocity information into the phase of the MRI signal. In this study, both techniques are used to probe the pressure-driven steady flow of water in a pipe with a step stenosis. The velocity measurements were then compared with computational results obtained using the FIDAP software package. The experiments show that the phase contrast method gives more accurate results, with 90% of the measurements within 10% of the local computational fluid dynamics (CFD) velocity predictions at Re = 100 and 94% of the measurements within 10% of the local CFD predictions at Re = 258. Although the time-of-flight experiments were not as accurate, they provide a good qualitative image of the flow field. Sources of the discrepancies between the MRI data and the CFD results are also discussed, including acceleration and spin flow-through artifacts. [References: 24]
机译：磁共振成像（MRI）是一种通用的无创工具，可实现复杂流体流的全场定量可视化。 MRI信号由射频（RF）脉冲与暴露于强静态磁场的核自旋的相互作用产生。 MRI测速的两种主要技术是飞行时间和相位对比技术。飞行时间技术涉及标记和跟踪流体的材料体积，而相衬技术则使用磁场梯度将速度信息编码为MRI信号的相位。在这项研究中，这两种技术都被用来探测具有阶梯性狭窄的管道中压力驱动的稳定水流。然后将速度测量值与使用FIDAP软件包获得的计算结果进行比较。实验表明，相衬法可提供更准确的结果，在Re = 100时，90％的测量值在局部计算流体动力学（CFD）速度预测的10％范围内，而94％的测量值在局部CFD的10％范围内Re = 258时的预测值。尽管飞行时间实验的准确性不高，但它们提供了流场的良好定性图像。还讨论了MRI数据和CFD结果之间差异的来源，包括加速度和旋转流过的伪像。 [参考：24]

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