Bending and Break-up of a Liquid Jet in a High Pressure Air-flow

The aim of this paper is to investigate the characteristics of the atomization process of a liquid jet injected into a high-pressure air cross-flow, i.e. in condition similar to that occurring in the inlet duct of a LPP gas-turbine burner. The influences of controlling parameters such as air velocity, liquid velocity and diameter of the nozzle are considered. The main features of the spray morphology were determined by means of a tomographic visualization technique and the general evolution of the spray in some typical cases is presented in the paper. It is shown as the jet evolution is significantly influenced by the onset of a stripping atomization mechanism marked by the peculiar morphology of the spray cross-section. This is also evident from the observation of the jet trajectories determined by using a shadowgraphic technique. The different behavior of the atomization process induced by the stripping mechanism led to a bi-stable evolution of jet trajectory in dependence of the prevalence of the liquid or air velocities effects. This feature can be hardly modeled by the interpolating function proposed in the literature. As a consequence, a stronger effort to gain a deeper understanding of the fluid dynamic, involved in the jet break-up in presence of an air cross-flow, is still required in order to build-up a more realistic model of the jet trajectory evolution.