Study on atomization effect of droplets in venturi reactor with different characteristic parameters

Abstract

In the field of preparation of cerium oxide by Venturi jet pyrolysis reactor, the spray pyrolysis process can achieve energy saving and environmental protection. The atomization effect of transverse air flow on the droplet directly affects the morphology of the product, and this research can improve the high value of cerium oxide applications. In this paper, a novel Venturi jet pyrolysis reactor has been developed. The atomization stage in the preparation process was studied by combining experiment and numerical simulation. The results show that the entire atomization process can be divided into primary atomization and secondary atomization. The primary atomization process of the liquid jet consists of columnar fragmentation and surface fragmentation, which are dominated by Rayleigh–Taylor (R-T) instability and Kelvin–Helmholtz (K-H) instability respectively. In the process of atomization of liquid column, the increase in gas velocity helps to promote the atomization. The Sauter mean Diameter value at 35 and 40 m/s gas velocity is the smallest, and the atomization effect of Venturi reactor is the best. With the increase in Weissenberg number (Wi), the crushing mode of droplets in Venturi reactor gradually changes from envelope to envelope—core and further evolves into core-layer. The core-layer crushing effect is the best, and the distribution range of daughter droplets is larger. The crushing state of atomized droplets in Venturi reactor is summarized. When Wi < 12, it is vibration crushing; when 12 < Wi < 30, it is packet crushing; when 30 < Wi < 45; it is pack-core crushing; and when 45 < Wi < 75, it is stamen-layer breakage.