ID 425

4D Imaging of Primary Liquid Breakup Using High-Speed Tomographic X-ray Radiography

 

Abstract:

Four-dimensional x-ray measurements are demonstrated in an optically complex spray using three x-ray sources and three high-speed imaging systems. Three imaging systems captured high-speed two-dimensional radiographic information of the sprays. Each imaging system was composed of a high-flux rotating anode x-ray tube source, a CsI phosphor plate, an f/2 objective, high-speed visible light image intensifier lens-coupled to a high-speed CMOS camera. The spray was illuminated with short bursts from the continuous wave x-ray sources projecting radiographs onto the phosphors and the visible images were collected at 10–50 kHz with the visible imaging system. These data were converted to a quantitative equivalent path length (EPL) of liquid using the Beer–Lambert law with a variable attenuation coefficient dependent on x-ray photon energy. The 3D structure is obtained by utilizing an algebraic reconstruction technique (ART) after normalization and calibration of the x-ray signals using commercially available LaVision DaVis 8 tomographic imaging software. These data enable analysis of the evolution of internal liquid structures within optically complex or optically dense sprays and reveal the dynamics of coherent liquid structures representing primary liquid break-up phenomena in the injector near field.

This manuscript has been cleared for public release by the Air Force Research Laboratory (No. 88ABW-2018-1181).