Modelling of the atomization of a plain liquid jet in crossflow in the LPP premise duct at DLR

Abstract

The penetration and atomization of a plain jet of kerosene fuel in a crossflow of air were modelled and compared with the experiment at test conditions relevant to lean premixed prevaporized combustion in gas turbines. The underlyning tests had been conducted in the DLR premix duct at an air velocity of 100 and 75 m/s and an air pressure of 3, 6 and 9 bar at ambient temperature. The fuel nozzle diameter had been 0.45 mm and the liquid-to-air momentum flux ratio had been between 2 and 19. Measurement techniques employed include time resolved shadowgraphs., Mie-scattering laser light sheets, and Phase-Soppler-Anemometry. Hence qualitative information on jet disintegration as well as quantitative data regarding jet penetration, fuel placement and dropsize distribution had been obtained. The numerical model predicts the jet penetration by treating the liquid fuel conceptually as a cylinder deflected by the airflow. Fracture of the liquid column is modelled by a characteristic time criterion. Shear breakup of the liquid column and its fragments is modelled as liquid boundary layer stripping. The engineering model has been implemented as an extension into a 3d CFD-code with Lagrangian particle tracking. Within its application limits, the model fills th gap of lacking droplet initiall conditions in numerical spray simulation, while at the same time requiring low computational effort.