A Mechanistic Assessment of Swirl Injection and Atomization by X-ray Radiographic and Optical Techniques

Abstract

Detailed x-ray radiographic and optical experiments were conducted to evaluate injection and atomization characteristics of a liquid rocket swirl injector. Sprays issued from a single swirl-coaxial element—with, and without, co-annular gas flow—were exposed to focused, monochromatic x-rays. Two dimensional time-averaged attenuation data were collected, revealing projected mass distribution of liquid in the injector near-field, as well as mass-weighted axial velocities integrated over time. Measurements of liquid film thickness and spray cone angle were also inferred from the x-ray radiography data. Intra-set comparisons of the x-ray data revealed the mechanistic influence of gaseous co-flow on the liquid sheet. Similar measurements were gathered from visible light imagery and compared to those resolved from x-ray data. Contrasts between these data sets shed light on the sensitivities of the image processing techniques implemented in the study.