X-ray fluorescence measurements of dissolved gas and cavitation

Daniel J. Duke, Alan L. Kastengren, Andrew B. Swantek, Katarzyna E. Matusik, Christopher F Powell

Research output: Contribution to journalArticleResearchpeer-review

25 Citations (Scopus)

Abstract

The dynamics of dissolved gas and cavitation are strongly coupled, yet these phenomena are difficult to measure in-situ. Both create voids in the fluid that can be difficult to distinguish. We present an application of X-ray fluorescence in which liquid density and total noncondensible gas concentration (both dissolved and nucleated) are simultaneously measured. The liquid phase is doped with 400 ppm of a bromine tracer, and dissolved air is removed and substituted with krypton. Fluorescent emission at X-ray wavelengths is simultaneously excited from the Br and Kr with a focused monochromatic X-ray beam from a synchrotron source. We measure the flow in a cavitating nozzle 0.5 mm in diameter. From Br fluorescence, total displacement of the liquid is measured. From Kr fluorescence, the mass fraction of both dissolved and nucleated gas is measured. Volumetric displacement of liquid due to both cavitation and gas precipitation can be separated through estimation of the local equilibrium dissolved mass fraction. The uncertainty in the line of sight projected densities of the liquid and gas phases is 4–6 %. The high fluorescence yields and energies of Br and Kr allow small mass fractions of gas to be measured, down to 10−5, with an uncertainty of 8 %. These quantitative measurements complement existing optical diagnostic techniques and provide new insight into the diffusion of gas into cavitation bubbles, which can increase their internal density, pressure and lifetimes by orders of magnitude.

Original languageEnglish
Article number162
Pages (from-to)1-14
Number of pages14
JournalExperiments in Fluids
Volume57
Issue number10
DOIs
Publication statusPublished - 1 Oct 2016
Externally publishedYes

Cite this