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Dynamic tracking of structures in multiphase flows by ultrafast X-ray tomography and image based scanning steering

通过超快 X 射线断层扫描和基于图像的扫描转向对多相流中的结构进行动态跟踪

基本信息

批准号：
316064903
负责人：
Dr.-Ing. Martina Bieberle
金额：
--
依托单位：
Institut für Energietechnik
依托单位国家：
德国
项目类别：
Research Grants
财政年份：
2016
资助国家：
德国
起止时间：
2015-12-31 至 2021-12-31
项目状态：
已结题

来源：
https://gepris.dfg.de/gepris/projekt/316064903?language=en
关键词：
Dynamic tracking structures multiphase flows

项目摘要

Ultrafast imaging techniques are indispensable tools for the analysis of highly dynamic processes such as multiphase flows. The latter occur in many technical processes, e.g. in chemical multiphase reactors, in manifold ways. Modelling of multiphase flows using numerical calculation schemes (CFD) is especially demanding because of the multitude of physical effects to be considered for impulse, heat and mass transfer along with the multiple scales of the problem. For the development and validation of models for the numerical calculation of multiphase flows temporal and spatial highresolution measurement techniques, such as the ultrafast X-ray tomography system (ROFEX), which was co-developed by the applicant, are essential. The dimensioning of bubble columns, for example, relies significantly on the knowledge about the residence time behavior of the liquid as well as the gaseous phase. However, there are only few studies on the tracking of single bubbles in bubble columns, which are furthermore mainly limited to bubble columns with low gas fractions, where the single bubbles are not affected by swarm effects. Fluid mechanic investigations for determining the above mentioned parameters within a bubble swarm would strongly benefit from an online measurement technique for simultaneous measurement of bubble structure, bubble movement and surrounding phase distribution within realistic bubble columns.Therefore, the aim of the project is the advancement of the ultrafast X-ray tomography for tracking bubbles in a two-phase flow. The principle is based on a fast image steered positioning of the to-mography plane. Thus, gas bubbles can be tracked throughout their way through the flow region. During their passage, structural changes as well as interactions with other gas bubbles (coales-cence, fragmentation, and collision) can be observed. Furthermore, the complete flow structure within the imaging plane can be recorded. For the realization of dynamic experiments, efficient measurement, analysis and controlling techniques are essential. They are supposed to be obtained by interdisciplinary cooperation with the group of A. Kopmann (KIT), which possesses proved expertise in online data acquisition of large data amounts, 3D image reconstruction and image based controlling. Based on this knowledge, GPU based image reconstruction and image analysis algorithms in combination with a fast data transfer solution should be designed, developed and implemented at the ROFEX system. Concrete aim is the demonstration of the feasibility of tracking a single bubble of a bubble swarm within a bubble column. The main challenge lies in the verification of the realtime capability of data transfer and the whole data analysis chain.

超快成像技术是分析多相流等高度动态过程不可或缺的工具。后者以多种方式发生在许多技术过程中，例如在化学多相反应器中。使用数值计算方案（CFD）对多相流进行建模是特别苛刻的，这是因为要考虑脉冲、热和质量传递沿着问题的多尺度的大量物理效应。为了开发和验证多相流数值计算模型，时间和空间高分辨率测量技术，如申请人共同开发的超快X射线层析成像系统（ROFEX）是必不可少的。例如，鼓泡塔的尺寸设计主要依赖于关于液相和气相的停留时间行为的知识。然而，只有很少的研究，在鼓泡塔中的单个气泡的跟踪，而且主要限于鼓泡塔与低气体分数，其中的单个气泡不受群体效应。同时在线测量气泡结构、气泡运动和周围相分布的技术将极大地有助于确定气泡群中上述参数的流体力学研究，因此，本项目的目的是发展用于跟踪两相流中气泡的超快X射线层析成像技术。该原理基于断层摄影平面的快速图像导向定位。因此，气泡可以在其通过流动区域的整个路径上被跟踪。在它们通过的过程中，可以观察到结构变化以及与其他气泡的相互作用（聚结，破碎和碰撞）。此外，可以记录成像平面内的完整流动结构。为了实现动态实验，有效的测量、分析和控制技术是必不可少的。它们应该通过与A组的跨学科合作来获得。Kopmann（KIT）在大数据量的在线数据采集、3D图像重建和基于图像的控制方面拥有公认的专业知识。基于这些知识，基于GPU的图像重建和图像分析算法结合快速数据传输解决方案应该在ROFEX系统中设计、开发和实施。具体的目的是证明在鼓泡塔内跟踪气泡群中单个气泡的可行性。主要挑战在于验证数据传输的实时能力和整个数据分析链。