Modeling of an efficient airblast atomizer for liquid jet into a supersonic crossflow

Abstract

The liquid jet from an airblast atomizer into supersonic air crossflow with a Mach number of 1.94 was investigated numerically. The detached eddy simulation was used as the turbulence model to compromise the merits of both large eddy simulation and k−ε models. The Kelvin-Helmholtz and Rayleigh-Taylor (KHRT) model was used to simulate the droplet breakup process. The location and velocity of the child droplets are tracked efficiently by the automated tracking scheme. The model was validated using previous experimental data and a good agreement was obtained. In the present study, the airblast atomizer, which allows core and annular air flows with the injected liquid, is utilized instead of the ordinary orifice nozzle to improve the breakup process and the droplet distribution. The airblast atomizer dimensions were represented as factors of the ordinary orifice nozzle and the air mass flow rates through the atomizer were adjusted as ratios from the liquid mass flow rate. The effects of these parameters on the spray structure characteristics were presented. Then, a new proposed design for the airblast atomizer was suggested based on the improvements in spray characteristics dimensions and sauter mean diameter distribution. The core and annular air flows significantly enhanced the spray characteristic dimensions and spray breakup compared with the ordinary orifice nozzle.