Measurement of Liquid Core Length of a Coaxial Two-fluid Spray

Shadowgraphs, tube-source X-ray radiographs, and synchrotron X-ray radiographs from a coaxial two-fluid spray are analyzed to measure the liquid core length of the spray. Two flow conditions: Rel = 1,100, Reg = 21,300, We = 40, and Rel = 1,100, Reg = 46,700, We = 196 are investigated. The standard deviation of the fluctuating intensity values are calculated and analyzed to estimate the liquid core length. Additionally, the largest connected domain is used to find an instantaneous breakup position of the spray. The results show that the high standard deviation region is related to the ligament development region, and the instantaneous position identifies ligament formation in the spray

Fluid Flow Observations of the Spray Near-Field using High-Speed X-ray Imaging

Sprays are important to many industrial processes, but the near-field region where spray formation takes place is difficult to visualize and characterize through visible light imaging because this region is typically optically dense. X-ray imaging is one technique that can penetrate this optically dense region and provide unique observations of the spray formation process. This study uses high-speed white beam X-ray imaging conducted at the Advanced Photon Source to capture spray formation dynamics from a canonical airblast atomizer. A range of momentum flux ratios are visualized by varying the gas flow rate while the liquid flow rate is held constant. The X-rays show overlapping flow structures including bags, ligaments, mushrooms, and webs. Air bubbles are captured within the liquid regions, and a very dynamic crown forms at the liquid needle exit at higher momentum flux ratios. Finally, at the highest momentum flux ratios, air bubbles and liquid droplets are observed migrating upstream in the center of the crown, and this motion is attributed to a toroidal recirculation cell at the nozzle exit.This is a manuscript of an article published as Bothell, Julie K., Timothy B. Morgan, Alan L. Kastengren, and Theodore J. Heindel. "Fluid Flow Observations of the Spray Near-Field using High-Speed X-ray Imaging." Journal of Flow Visualization and Image Processing 29, no. 2 (2022). DOI: 10.1615/JFlowVisImageProc.2021040154. Copyright 2022 Begell House. Posted with permission