Movement and Hydrodynamic Instabilities of Particle-Laden Liquid Jets in the Centrifugal Field Influenced by a Gas Flow

In several industrial applications like spray drying or coating technologies, rotary atomizers are used for atomization of fluids. To control the fluid motion and to intensify transfer processes, rotary atomization is often combined with gas flows. The present work introduces experimental and theoretical studies on this issue. Model–theoretical basics and experiments were worked out for the breakup of a stretched, viscous, particle-laden, laminar liquid jet in the centrifugal field. In addition, the research takes into account the influence of an imposed gas flow which is directed parallel to the axis of rotation. Based on perturbation analysis, the physical–mathematical model consists of two parts. Balances of mass and forces provide the time steady flow and thus 3D jet motion and mean jet contour. Considering Rayleigh-type jet disintegration a linear stability analysis is used to examine the stability behavior of the jet. Spatial and temporal evolution of disturbances and finally median drop sizes are both calculated with a dispersion equation. The dispersion equation is based on a potential flow for the gas phase and on an Eulerian formulation for the balances of impulse and mass of the liquid and the solid phase. Experiments under various operating conditions and boundary conditions complete our investigations. Two shadow imaging systems provide projections from top and side. Therefore, three-dimensional jet motion is analyzable. Furthermore, jet length is determined and serves as a boundary condition for the modeling. Using a telecentric lens for the imaging from the side, drop sizes and jet thickness are measureable although jet and drops are moving three-dimensionally. Calculation results and experimental data are compared and show good accordance.