Numerical study on pre-film atomization mechanism and characteristics by a coaxial swirl injector

Abstract

The overall process and mechanism of the centrifugal pre-film atomization with double swirling flow were studied using the methods of large Eddy simulation and volume of fluid. The atomization process includes a centrifugal jet under the primary swirl and a pre-film atomization under the two-stage counter-rotating swirl at the venturi outlet. The fuel is ejected from the outlet of the centrifugal nozzle and undergoes the transient process of reaching the venturi throat. The breaking mechanism of liquid film in this process is the same as that of the formation mechanism of the mushroom-shaped tip of liquid jet. The numerical simulation results are highly consistent with the experimental results. For the formation and development of the liquid film on the venturi wall, collision and wave action promote the expansion of the liquid film. At the outlet position of the venturi tube, the short wave mode and the two-stage reverse swirling structure play major roles in the fragmentation process of the flake liquid film, which coincides with the flow characteristics given by the experiment. It is found that the spray cone angle increases as the fuel flow rate increases, and the numerical results are basically consistent with the predicted values of the empirical formula under different fuel flow rates. The droplet size distribution showed a Poisson distribution during the atomization of centrifugal jets and pre-film, and the peak position and variation trend of the droplet size distribution at the outlet of the venturi tube were basically consistent with experimental results.

Simulation study on the effect of jet parameters on the jet flow of a swirl nozzle

“…In the study of the vortex, it is believed that there is a backflow area inside the swirl nozzle and the K-H surface wave is captured. Zhang et al [5] used LES and VOF to study the entire process of dual-cyclone centrifugal pre-film atomization. The study found that collisions and waves promote the expansion of the liquid film, which is consistent with the flow characteristics given in the experiment.…”

Effect of Upstream Valve Opening Process on Dynamic Spray Atomization of Bipropellant Thruster Injector

“…It was concluded that increasing the ambient pressure increased the size of droplets in all of the spray regions, with decreased secondary atomization. Zhang et al researched the overall process of double swirl atomization using the methods of large eddy simulation and volume of fluid [13]. In the simulation, they observed two wave patterns in the development of spray, with variable droplet size distribution.…”