Cross-sectional droplets distribution of a liquid jet in supersonic crossflow

An experimental study on the atomization characteristics of a liquid jet in supersonic crossflow is conducted to analyze fuel atomization in a high-speed air-breathing propulsion system. Phase Doppler Anemometry (PDA) is used to obtain the droplet size and cross-sectional shape. The influencing factors are investigated experimentally, and the droplet size distribution is predicted based on the maximum entropy principle. The results demonstrate that the spray cross-section in supersonic crossflow is approximately Ω-shaped, and the heights and widths increase linearly with an increase in the orifice diameter. The range of the cross-sectional droplet size is 0–30 μm, and the dominant influencing factor is the aerodynamic force. The cross-sectional droplet size depends on the transverse direction distance but not the orifice diameter. As the transverse distance increases, the peak intensity of the curves increases, and the droplet size becomes more uniform. The empirical relationship between the characteristic average diameter and the transverse distance at a specific distance (10–50 mm) from the orifice is obtained from the experimental data. The characteristic average diameter constraint method based on the maximum entropy principle provides an accurate prediction of the cross-sectional droplet size distribution.