ID 33

Quantitative Characterization of Time-Averaged Three-Dimensional Mass Distributions for Liquid Jets in Subsonic Crossflows Using Confocal X-Ray Fluorescence

 

Abstract:

Quantitative time-averaged three-dimensional mass distributions within the plumes of liquid jets in a subsonic crossflow environment were characterized using confocal x-ray fluorescence at the 7-BM beamline of the Advanced Photon Source at Argonne National Laboratory. A small-scale wind tunnel with a test section of 50 mm (H)  50 mm (W)  152 mm (L) provided a freestream flow up to Mach 0.3. The wide windows of the test section are fitted with a thin Polyimide film for high x-ray transmittance. An axisymmetric aerated-liquid injector fitted with an exchangeable adaptor was used to generate a pure- or aerated-liquid jet at the desired injection conditions. Water and nitrogen, which was used as the aerating gas for aerated-liquid jet, were doped with bromine and krypton, respectively, at low concentrations, to facilitate the x-ray fluorescence measurements. For the first time, the capability of a confocal x-ray fluorescence technique to quantitatively measure the cross-sectional liquid and gas (for aerated-liquid jets) distributions within the discharged plumes in crossflows was successfully demonstrated. For the aerated-liquid jet, it was found that the gas plume exhibits a smaller cross section and is mainly located at the inner lower center of the entire plume cross section in the far field. The unique phenomenon of plume crossing between gas and liquid plumes was also observed within the near field of an aerated-liquid jet. The measured cross-sectional mass distributions were compared with previous phase Doppler particle analyzer (PDPA) measurements, in order to provide more understandings of the planar plume structures.