X-ray Measurement Techniques Used for Wall-Bounded Cavitating Flows

This chapter is devoted to X-ray measurement techniques that are suitable for cavitating flows, the physics behind the interaction of X-rays with matter, and how the findings can be interpreted to provide information on (1) the topology and dynamics of the two-phase flow in a qualitative manner in order to illustrate the shape evolution of the arising vapor structures characteristic of different cavitation regimes and (2) the actual extent of vapor forming in terms of quantitative void fraction data. The experimental infrastructure necessary for the generation of X-ray beams with diverse characteristics (photon flux, energy, spectrum, and direction) and relevant instrumentation to extract physical information, as well as the flow configurations with reference to cavitating flows that have been investigated so far in the literature, are discussed in detail. X-ray diagnostics that have been proposed as applicable to cavitation studies can be broadly categorized as X-ray absorption (densitometry), X-ray phase contrast imaging, X-ray computed tomography, and X-ray fluorescence spectroscopy.