X-Ray Flow Visualization: Techniques and Applications

Multiphase flows, defined as a discrete phase in a continuous fluid phase, are found in many natural, industrial, and consumer flows, from rain fall and avalanches to petroleum processing and fuel combustion to cookie dough mixing and pasta making. Many of these flows have an interior that is hidden from optical flow measurements, and intrusive probes can modify the flows of interest. Noninvasive measurement techniques, like X-ray flow visualization, provide a means to visualize and quantify the flow conditions in areas obstructed to visual access. Additionally, X-rays are unlikely to modify or alter the flow of interest. This paper reviews various X ray flow visualization techniques, including those using X-rays from tube sources, electron guns, and synchrotron sources. X-ray fundamentals are first reviewed. Then, various X ray imaging techniques are highlighted, and applications of those techniques are summarized using several multiphase flow examples. Advantages and disadvantages of each technique are provided and the unique flow features that can be captured with X-ray flow visualization are summarized. As detailed, X-ray flow visualization is a powerful tool for multiphase flow visualization and characterization, particularly when the flow of interest has limited or no optical access.