The Mathematical Model for the Secondary Breakup of Dropping Liquid

Experimental Studies and Condition Monitoring of Auxiliary Processes in the Production of Al2O3 by Sol–Gel Technology

Powders and granules of heavy metal oxides produced through condition monitoring are in high demand as intermediate products for obtaining fine-grained ceramics for a wide range of applications, i.e., nuclear fuel and fuel elements for nuclear power plants. Sol–gel technology to produce nuclear fuel (UO2), as well as catalysts (ThO2) for organic synthesis in the form of granules from pressed microspheres, is a promising method to obtain powders and granules of heavy metal oxides (fine-graded ceramics). Al2O3 was selected as the model analog at the stages of obtaining a solution of heavy metal and sol, the formation and gelation of droplets, and the preparation of gel spheres and their further washing and drying, as well as recovery and firing of particles. In the study, the main parameters were substantiated, e.g., the diameter and angle of inclination of the axis for the holes in the perforated shell, the multiplicity of sol circulation before the holes, the coefficients of liquid (sol) flow rate, the oscillation frequency of the disperser, and the concentration of surfactant and acid in sol. All of these parameters affect the characteristics of the granules that are obtained by sol–gel technology. Moreover, recommendations to increase productivity and the energy efficiency of production were also given. In particular, it was found that oscillation frequency in a range of 70–80 Hz leads to a granulometric composition of the obtained granules of 2.0–2.2 mm. A hole of 0.85 mm and a frequency of 100 Hz slightly change this range to 1.2–2.0 mm, while maintaining monodispersity.

Collisions of Liquid Droplets in a Gaseous Medium under Conditions of Intense Phase Transformations: Review

The article presents the results of theoretical and experimental studies of coalescence, disruption, and fragmentation of liquid droplets in multiphase and multicomponent gas-vapor-droplet media. Highly promising approaches are considered to studying the interaction of liquid droplets in gaseous media with different compositions and parameters. A comparative analysis of promising technologies is carried out for the primary and secondary atomization of liquid droplets using schemes of their collision with each other. The influence of a range of factors and parameters on the collision processes of drops is analyzed, in particular, viscosity, density, surface, and interfacial tension of a liquid, trajectories of droplets in a gaseous medium, droplet velocities and sizes. The processes involved in the interaction of dissimilar droplets with a variable component composition and temperature are described. Fundamental differences are shown in the number and size of droplets formed due to binary collisions and collisions between droplets and particles at different Weber numbers. The conditions are analyzed for the several-fold increase in the number of droplets in the air flow due to their collisions in the disruption mode. A technique is described for generalizing and presenting the research findings on the interaction of drops in the form of theoretical collision regime maps using various approaches.