Prediction of droplet size distributions from a pre-orifice nozzle using the Maximum Entropy Principle

Abstract

The atomized droplet size distribution (DSD) produced by a nozzle is a fundamental information to define the performance of application systems. In this paper a new model to represent the atomization of a pre-orifice nozzle is presented. It is based on the Maximum Entropy Principle (MEP), the Linearized Instability Sheet Atomization (LISA) model and Computational Fluid Dynamics (CFD) simulations. Different atomization liquids with varied physical properties were sprayed at different pressures and their droplet size distributions were measured for model calibration and validation. The LISA model correctly predicts the effect of the pressure and physical properties of the mixtures on the most probable droplet diameter. The CFD studies allow to predict the influence of the flowrate on the energy source term of the MEP energy balance, which is not negligible. On the other hand, based on the LISA model, the calculated momentum source term does not impact on the DSD prediction significantly. The developed model, which just includes two adjustable parameters, is able to well represent experimental DSDs from a pre-orifice nozzle operating at different pressures.