Large Eddy Simulation and Experimental Study of a Controlled Coaxial Liquid-Air Jet

Abstract

This paper describes the numerical and experimental study of the control of the trajectory and spreading of an air-assisted water spray. The configuration is a coaxial set up where the liquid injected by the central tube is atomized by a surrounding high-speed annular air flow. This spray is actuated in its outlet plane using additional air jets to modify either its trajectory or its spreading angle (by adding swirl). Large eddy simulation is used jointly with experimental measurements (hot-wire anemometry for the air flow without spray and phase Doppler anemometry for the spray cases) to analyze the flow with and without control. Results show that 1) large eddy simulation of two-phase flows using a Lagrangian solver is a precise method to predict such flows, and 2) the spray jet can be effectively modified using simple actuators, suggesting that the same devices applied to fuel sprays in combustion chambers, would be an effective active control actuator. Large eddy simulation results also reveal the complex flow patterns and effects on droplet distribution induced by the actuators and appear as an excellent tool to complement and understand experimental data.