Near-field Characterization of an Airblast Atomizer Using Broadband X-ray Radiography

Sprays are widely used in industrial processes. X-ray measurement methods based on absorption provide useful tools that eliminate refraction and reflection that complicate visible light measurements. Synchrotron X-ray sources can provide accurate and detailed measurements because of the strong penetration of the high-energy X-rays. Compared with synchrotron X-ray sources, X-ray tube sources operate at lower energy and are easier to operate, but beam hardening and penumbra effects may complicate data analysis. However, after proper calibration, radiographs from X-ray tube sources can provide detailed information of the spray near-field compared to limited conditions from synchrotron X-ray measurements. In this research, broadband X-ray radiography is performed to obtain the time-average equivalent path length (EPL) of the spray near-field region of an airblast atomizer operating under various conditions. The EPL distributions show a Gaussian self-similar behavior in the spray near-field. Spray angles are determined by the positions of the half maximum EPL. Spray breakup length is measured and compared to high-speed white beam images from the Advanced Photon Source at Argonne National Laboratory.