Numerical simulation of dual-orifice centrifugal nozzle liquid sheet breakup and coalescence process

To address the limitations in existing research regarding the liquid sheet coalescence mechanism and flow field evolution of dual-orifice centrifugal nozzles, the study employs a coupled Volume of Fluid and Discrete Phase Model combined with Large Eddy Simulation. A collaborative framework of multiphase flow numerical simulation and experimental validation is constructed to systematically investigate the primary breakup, secondary atomization, and dynamic coalescence processes. Through comparison with experimental results, the numerical model's accuracy in predicting the atomization cone angle and fuel flow rate is validated, with errors controlled within 10%. The study reveals that the liquid sheet breakup mechanism is significantly influenced by the Weber number: residual energy of surface waves drives filament rupture under low Weber number conditions, whereas turbulent fluctuations dominate under high Weber number conditions, exhibiting higher breakup efficiency. Under the dual-orifice cooperative condition, the merging of liquid sheets leads to increased thickness and reduced surface shear forces. This inhibits the energy input required for secondary breakup, causing the Sauter mean diameter to increase compared to the single-orifice operation of the main fuel circuit. Furthermore, the paper highlights a coalescence mechanism dominated by cavity negative pressure in the central recirculation zone, categorizing the process into four characteristic phases. The high-frequency fluctuations of this cavity pressure directly lead to the periodic “contact-separation” of the liquid sheets, triggering phased adjustments and hysteresis of the atomization cone angle.