Numerical study of the effect of surface topography on atomization performance in geometrically sensitive areas of centrifugal nozzles

Integral three-dimensional printing of aeroengine fuel nozzles is an emerging trend. However, the large relative roughness of the internal flow paths created by this processing method is problematic. To study the influence of the rough surface morphology on atomization performance in geometrically sensitive areas of centrifugal nozzles, this paper describes numerical simulations of the atomization process of five nozzle models with rough orifice sections. The simulation framework considers a coupled internal and external flow in stages. The macroscopic morphology of the numerically calculated spray field is found to be consistent with experimental results, with maximum errors in the Sauter mean diameter, spray angle, and flow rate of just 8.7%, 3.7%, and 6.1%, respectively. The numerical results show that the nozzle's rough surface morphology in geometrically sensitive areas has a non-negligible impact on the liquid film velocity fluctuations, primary breakup, and secondary atomization characteristics. Indeed, the effect on primary breakup is large, with the maximum difference between the five rough-surface models reaching 22.9%. The effect on secondary atomization is small, with a maximum difference of just 5.7% except in the number of droplets, which has a maximum difference of 22.1%. Among the five rough-surface models, the atomization characteristics of the smooth model differ greatly from those of the real model, whereas a power-function model best reflects the real surface morphology. This study provides new ideas for nozzle performance prediction and optimization, and provides a reference for engineering applications of three-dimensional printed centrifugal nozzles.