CFD modelling of primary atomisation of diesel spray

Primary atomisation in a high-pressure diesel jet is modelled using Large Eddy Simulation. The Volume Of Fluid phasefraction based interface capturing technique was applied in the Eulerian framework using the open source CFD code OpenFOAM. Conditions modelled replicate those of a parallel experimental program including nozzle inlet pressure change, spray chamber pressure (ambient zone) and temperature and viscosity of both phases. The nozzle geometry was obtained using X-ray Computed Aided Tomography. Diesel fuel pressure at sac inlet was defined based on injection pressure profile (ranging from 30 to 1200 bar) captured during experimental tests. The effect of different grid sizes with mesh resolutions of 2.5, 8, and 18 million cells on primary breakup was investigated. The results assist with understanding the flow behaviour during primary break up, including commencement of fragmentation and the early spray cone angle. The results also showed that the jet break-up increased in meshes with higher resolutions. Furthermore, investigation of in-nozzle flow indicated a non-axisymmetric behaviour. The early spray angle of the numerical results was more than the experimental data, probably due to cavitation and compressibility not being modelled. These effects will be studied in forthcoming works.