Energy Reports (Nov 2021)
Numerical prediction of the spray from an air-assisted fuel injection system via Eulerian–Lagrangian approach
Abstract
Air-assisted fuel injection (AAFI) systems may be installed in aviation piston engines for atomization of heavy fuels. However, there are few studies on the in-cylinder air-assisted spray characteristics, which affects the improvement of AAFI engine performance. In this study, an improved air-assisted spray simulation method based on ANSYS FLUENT was proposed to predict the changes in air-assisted spray characteristics alongside spray development, compared with previous simulations, the simulation in this paper was extended in both temporal and spatial domains and more accurate boundary conditions were given. The Eulerian–Lagrangian approach was used to represent the two-phase spray flow and a dynamic mesh model was used to simulate the movement of injector needle valve. The improved method was validated by comparison against experimental results in terms of spray shape, spray volume, spray penetration, spray droplet size spatial distribution, and overall Sauter mean diameter (SMD). By using the improved method, the average relative errors of the simulation results in spray volume and spray penetration were reduced by 13.5% and 10.2%, respectively. Additionally, some typical spray field parameters (gas phase pressure, gasified fuel mass fraction, etc.) were analyzed. The improved method can be used to study the in-cylinder air-assisted spray characteristics, which is beneficial for the fuel injection parameter optimization and the combustion chamber design of the AAFI engine.
