Influence of Spray Velocity and Structure on the Air Entrainment in the Primary Breakup Zone of High Pressure Diesel Sprays Available to Purchase

Nozzle geometry and rail pressure influence the gas-liquid momentum transfer and the turbulent dispersion in the primary breakup zone of high-pressure Diesel sprays, and consequently the combustion processes. To investigate these phenomena, different measuring techniques have been used. The spray structure is visualized using shadowgraphy and scattered light imaging, and the axial velocities in the dense spray region have been measured using a Laser Correlation Velocimeter. Gas velocities are measured using Particle Image Velocimetry. It is found that the dimensionless velocities (related to the frictionless velocity) are independent of the injection pressure and the nozzle geometry. However the momentum transfer between the liquid phase and the surrounding air strongly depends on the spray structure. Here a sharp edged nozzle inlet promotes cavitation and turbulence levels in the nozzle which leads to stronger breakup and significantly enhanced air entrainment.