From Event: SPIE Optical Engineering + Applications, 2019
The multi-phase flow within a steel diesel injector is imaged using synchrotron-produced X-rays from the Advanced Photon Source at Argonne National Laboratory. Projections gathered from several repeated injection events at up to 10,000 frames per second and with 2.1 micrometer resolution at various viewing angles resulted in a 4D data set. Photon statistics were improved by averaging the data over 200 injection events. Owing to significant attenuation caused by the injector body material, and the short exposure time, the images are obscured by various types of noise making tomographic reconstruction challenging. Attempts at denoising this data are discussed.
At each time step, translational and rotational image registration was performed to align projections obtained from different lines-of-sight. This is followed by a Fourier Transform method for computed tomography to reconstruct the 3D flow-field, from the start to end of fuel injection, which is a 2 millisecond long event. The X-ray phase contrast in the data was exploited by applying a low-pass filter. Segmentation is performed to track the location of the liquid-gas interface, thus distinctly revealing a highly asymmetric flow-separation layer affected by micron-scale features in the nozzle geometry. This complete data processing pipeline converted the images acquired at a signal-to-noise ratio of 1 into a unique tomographic dataset of internal fluid flow through approximately 2 millimeters of steel. The data shows excellent validation with computational fluid dynamics simulations of the flow profile previously obtained for this nozzle.
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Aniket Tekawade, Brandon A. Sforzo, Katarzyna E. Matusik, Alan L. Kastengren, and Christopher F. Powell, "Application of synchrotron x-ray imaging and micro-CT to 4D visualization of multiphase flow inside a steel fuel nozzle (Conference Presentation)," Proc. SPIE 11113, Developments in X-Ray Tomography XII, 1111310 (Presented at SPIE Optical Engineering + Applications: August 14, 2019; Published: 17 September 2019); https://doi.org/10.1117/12.2527585.6084128408001.