Turbulence chamber design of a pre-orifice nozzle using CFD

RENAUDO, CARLOS A.; BERTIN, DIEGO E.; BUCALÁ, VERÓNICA

Buenos Aires

Congreso; WCCE11 - 11th World Congress of Chemical Engineering; 2023

Asociación Argentina de Ingenieros Químicos

Poster y trabajo completo aceptados. Congreso en Junio de 2023Droplet size distribution (DSD) is a major factor influencing the spray deposition on the target crop, and depends on the nozzle design, the atomized solution and the operating conditions. Specifically, pre-orifice nozzles include a chamber before the exit orifice that increase the flow turbulence. This design provides larger droplets at the same atomization pressure compared to standard nozzles. In this work, computational fluid dynamics (CFD) were used to study the influence of the flow behavior in a TeeJet TT11003. First, simulations based on both the geometry (2D and 3D), modeling approaches (one or two phases) and physical phenomena involved (e.g., turbulence models) were compared. Pressure drop, velocity and turbulent kinetic energy were analyzed. For these variables, grid convergence index (GCI) studies were performed. To ensure repeatability and software independency, one-phase simulations were performed in Ansys Fluent 19 and Openfoam 9 and the results were compared. It was observed that one-phase 3D simulations using the k-w SST turbulence model showed the best relation between accuracy, convergence, and simulation time. Second, CFD results were used together with a mathematical model to predict the atomized DSD of two alternative design of the turbulence chamber. Design I had reduced the length of a side of the turbulence chamber while in design II, the diameter of the same side of the turbulence chamber was increased. Compared to the original design, both cases produced less pressure drop for the same mass flowrate. Regarding the predicted DSD, finer droplets are expected to be produced by both designs.