MRI: Development of an X-ray System for Noninvasive 3-D Imaging of Large-Scale Multiphase Flows

这笔拨款将用于开发x射线系统，对大规模多相流进行无创三维成像。这种新仪器将允许在许多行业中发现的许多多相流过程的研究，表征和建模，包括燃料生产，商品和特种化学品生产，矿物加工，纸浆和造纸生产，废水处理，食品加工，生物有机体和制药生产。多相流包括气液、气固、液固和气液固混合物。描述和量化多相流的主要困难在于系统通常是不透明的；即使空气-水系统在相当低的气体体积分数下也变得不透明。这就需要在确定内部流动和输送特性时使用侵入性测量探头或非破坏性（非侵入性）方法。侵入式探针的困难在于它们会改变多相系统的内部流动，干扰实际的过程测量。x射线成像方法提供了一种无创测量技术，广泛用于具有复杂结构的静态物体的产品测试和评估。该项目将开发一种仪器，利用x射线透视、x射线立体成像和x射线计算机断层成像技术来表征多相流过程的特性，包括那些动态和时间相关的特性。该项目将开发x射线硬件、软件和设备，以完成大型垂直柱中多相流的x射线计算机断层扫描（即CT扫描），提供典型分辨率为500微米的时间平均局部相位分布。在这个项目中开发的系统将允许研究高达4米高、直径32厘米的垂直柱。这些尺寸将首次允许对这些工业上重要的系统进行调查，而不会受到壁效应或侵入性探针的机械干扰的严重干扰。来自各行各业的各种支持信都强调这是一种迫切的需求。在过去的三年里，计算机能力的爆炸式增长使人们第一次有能力获取、处理和显示这些复杂系统所需的数据量。将开发的仪器将包括x射线立体成像和立体重建的新应用，以三维方式可视化时间分辨流结构。这种新的、独特的能力将允许测量复杂多相流中目前无法获得的相特性，例如相上升/沉降速度、相轨迹、相合并和破裂速率、相生长和收缩速率。有了这台仪器，多相流内部特征的数据采集将有可能以足够的分辨率用于这些复杂流动的模型验证，并且，据我们所知，将提供目前在任何机构都无法获得的前沿研究能力。一旦该仪器被开发出来，许多其他ISU研究人员以及工业合作者（例如空气产品和化学公司，嘉吉公司，陶氏化学公司，Fluent公司，福斯特惠勒发展公司，金佰利公司，Potlatch公司，Proctor & Gamble公司和斯伦贝谢油田服务公司）已经确定了该仪器在研究气液、气固、液固和气液固流动方面的许多潜在用途。即使是传统的计算机断层扫描和需要大视野的工业部件的立体成像也可以用该仪器完成。该仪器还将为教师，学术和工业研究人员以及学生之间形成各种多学科合作提供独特的机会，并为公立大学的许多不同研究人员提供独一无二的仪器。

This grant will be used to develop an x-ray system to perform noninvasive three-dimensional imaging of large-scale multiphase flows. This new instrument will allow for the study, characterization, and modeling of numerous multiphase flow processes found in many industries including fuel production, commodity and specialty chemical production, mineral processing, pulp and paper production, wastewater treatment, food processing, and biological organism and pharmaceutical production.Multiphase flows involve gas-liquid, gas-solid, liquid-solid, and gas-liquid-solid mixtures. The principle difficulty in characterizing and quantifying multiphase flows is the fact that the systems are typically opaque; even an air-water system becomes opaque at fairly low volumetric gas fractions. This necessitates either the use of invasive measurement probes when determining internal flow and transport characteristics or nondestructive (noninvasive) methods. The difficulty with invasive probes is that they can alter the internal flow of the multiphase system interfering with realistic process measurements. X-ray imaging methods provide one family of noninvasive measurement techniques used extensively for product testing and evaluation of static objects with complex structures. The project will develop an instrument that utilizes x-ray radioscopy, x-ray stereography, and x-ray computed tomography imaging techniques to characterize properties of multiphase flow processes, including those properties that are dynamic and time dependent.The project will develop the x-ray hardware, software, and facilities to complete x-ray computed tomography (i.e., CT scans) of multiphase flows in large vertical columns, providing time-averaged local phase distributions with a typical resolution of 500 microns. The system to be developed in this project will allow for vertical columns up to 4 m high and 32 cm in diameter to be studied. These dimensions will allow for the first time, without significant interference of either wall effects or mechanical interferencefrom invasive probes, investigation of these industrially important systems. Various letters of support, from a variety of industries, have stressed this is a critical need. The explosion of computer power in the last three years allows for the first time the ability to acquire, process, and display the data volumes needed to adequately characterize these complex systems.The instrumentation that will be developed will include a novel application of x-ray stereography and stereographic reconstructions to visualize time-resolved flow structures in three dimensions. This new and unique capability will allow for the measurement of currently unavailable phase characteristics found in complex multiphase flows, such as phase rise/settling velocities, phase trajectories, phase coalescence and breakup rates, and phase growth and shrinkage rates. With this instrument, data acquisition will be possible of internal characteristics of multiphase flow at a sufficient resolution to be used for model validation of these complex flows, and, to our knowledge, will provide a leading edge research capability currently unavailable at any institution.Once this instrument is developed, many other ISU researchers, as well as industrial collaborators (e.g., Air Products and Chemicals, Inc., Cargill, Inc., DOW Chemical Company, Fluent, Inc., Foster Wheeler Development Corporation, Kimberly-Clark Corporation, Potlatch, Proctor & Gamble Company, and Schlumberger Oilfield Services), have identified many potential uses of this instrument in studying gas-liquid, gas-solid, liquid-solid, and gas-liquid-solid flows. Even traditional computed tomography and stereography of industrial components requiring a large field of view can be done with this instrument. This instrument will also provide a unique opportunity to form various multidisciplinary collaborations between faculty, academic and industrial researchers, and students, and provide a one-of-a-kind instrument at a public university to which many different researchers will have access.