Large two-stroke marine diesel engines have special injector geometries,which differ substantially from the configurations used in most other diesel engine applications.A major difference is that injector orifices are distributed in a highly non-symmetric fashion [1,2].Earlier investigations demonstrated the dependency of the spray morphology on the location of the spray orifice and therefore on the resulting flow conditions at the nozzle tip.Thus,spray structure is directly affected by the velocity distribution within the orifice [3].Following these earlier studies,the current work presents a detailed investigation of spray primary breakup by means of state-of-the-art Computational Fluid Dynamic(CFD)calculations.Here,the Star-CD computational platform was used for simulations of sprays relevant for large two-stroke marine diesel engines.In particular,Reynolds-Averaged Navier-Stokes(RANS)simulations were performed,including flow within the injector,and the results were utilized to implement initial conditions for Large Eddy Simulations(LES).The Dynamic Smagorinsky model was used for modeling subgrid-scale turbulence in LES [4].Utilizing proper estimates [5],different numerical grids were generated,characterized by computational cell size of the order of the Taylor microscale.The influence of grid density,as well as of the numerical time step value,on the simulation results was assessed.The LES results were found to strongly depend on numerical resolution parameters.The present results demonstrate the presence of highly asymmetric spray structure,in agreement with previous initial investigations [11].The asymmetry is the outcome of a strongly non-uniform velocity distribution at the orifice outlet,which affects the spray development in the combustion chamber.