ID 203

Feasibility of Monochromatic X-ray Imaging of the Near-Field Region of an Airblast Atomizer

 

Abstract:

The characterization of the atomization process in a spray is critical to improving the efficiency and effectiveness of sprays across a wide variety of industries. The near-field region of the spray is particularly important in this characterization as it provides insight into the mechanisms that drive droplet formation. Unfortunately, this region is also difficult to image due to its inaccessibility to optical techniques and the high speed of the events of interest. X-ray measurement techniques, such as white beam and focused beam radiography measurements, have been used to penetrate this dense liquid region and provide useful information. This paper presents a modification of the white beam measurement technique and investigates the feasibility of completing monochromatic X-ray radiography using the 7-BM beamline at the Advanced Photon Source at Argonne National Laboratory. Monochromatic X-ray radiography allows for the direct calculation of the effective path length at any location in the imaging area, but typically has a very low intensity, which has traditionally limited its use to point measurements (e.g., focused beam measurements). In order to demonstrate the potential and challenges of monochromatic beam radiography, time-resolved monochromatic X-ray images of a simple liquid stream and a low velocity spray from an airblast atomizer were acquired. Using these representative test data, it is shown that the monochromator used to generate the monochromatic beam introduced a non-uniform, time-varying, systematic imaging error. This error and its effect on the measurements will be demonstrated and discussed.