Spray in cross–flow: comparison of experimental and numerical approach

Abstract

The spray behaviour and droplet trajectories in realistic conditions are of crucial importance in many industrial, agricultural and chemical applications. Droplet characteristics and spray trajectory in chemical applications (e. g. flue gas scrubbing, CO2 capture in spray column) determine the amount of mass involved in the gas scrubbing process, mass trapped by the flow or attached to the walls. Knowledge of the droplet behaviour can improve a nozzle design and scaling, increase the process efficiency, minimize the process liquid and blow away the fraction. In this study, experiments with pressure swirl nozzle in cross–flow of air were performed at one nozzle injection pressure (0.5 MPa) and several cross–flow velocities (8, 16, 32 m/s). The results on droplet trajectories are compared with numerical results obtained by ANSYS Fluent. Two Lagrange approaches for spray modelling were used. Injection of droplet groups and Linearized Instability Sheet Atomization (LISA) model incorporated within ANSYS Fluent were used to represent the spray. The CFD results of spray penetration and droplet trajectories are compared with experimental data. A simple analytical model is able to well predict trajectories of large droplets, but fails to predict trajectories of small droplets. The LISA model yields a better accuracy for spray in cross-flow prediction.