Effects of Pulsation Amplitude on Primary Breakup and Spray Characteristics of an Aviation Kerosene Jet in Subsonic Crossflow

Pulsating injection offers a potential strategy for controlling fuel sprays in aerospace propulsion systems, yet the effects of pulsation amplitude on liquid-jet breakup and spray characteristics in gaseous crossflow remain insufficiently understood. In this study, a volume-of-fluid (VOF) method with adaptive mesh refinement (AMR) is employed to investigate aviation kerosene jets in a subsonic crossflow and quantify amplitude effects on atomization. The results show that increasing the amplitude intensifies local liquid-column deformation and promotes earlier primary breakup. As the pulsation amplitude (β) increases from 0.05 to 0.25, the surface wavelength remains nearly unchanged, whereas the necking ratio decreases by 55.7%, and the primary breakup distance is reduced by 16.79–49.26% relative to the steady jet. At a downstream distance of 70 injector diameters (x/d=70), the penetration depth of the pulsating jets is 9.37–14.38% greater than that of the steady jet and reaches its maximum at β=0.15 under the present conditions. For the pulsating jets, earlier primary breakup does not necessarily produce smaller downstream droplets. Under the common numerical resolution, the resolved downstream droplet population shows an overall shift toward larger sizes as the pulsation amplitude increases, as reflected by the increasing trends of the Sauter mean diameter (SMD), number-based median diameter (DN50), and number-based 90th-percentile diameter (DN90). These results clarify the distinct effects of pulsation amplitude on primary breakup, spray penetration, and downstream droplet size, providing guidance for amplitude selection in active fuel-spray control.