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Large Eddy Simulations (LES) provide instantaneous values indispensable to conduct statistical studies of relevant fluctuating quantities for diesel sprays. However, numerous realizations are generally necessary for LES to derive statistically averaged quantities necessary for validation of the numerical framework by means of measurements and for conducting sensitivity studies, leading to extremely high computational efforts. In this context, the aim of this work is to explore and validate alternatives to the simulation of 20-50 single realizations at considerably lower computational costs, by taking advantage of the axisymmetric geometry and the Quasi-Steady-State (QSS) condition of the near nozzle flow at a certain time after start-of-injection (SOI).

In the present work numerical simulations were carried out investigating the effect of fuel type, nozzle-geometry variations and back-pressure changes on high-pressure gas injections under application-relevant conditions. Methane, hydrogen and nitrogen with a total pressure of 500 bar served as high-pressure fuels and were injected into air at rest at 200 bar and 100 bar. Different nozzle shapes were simulated and the analysis of the results lead to a recommendation for the most advantageous geometry regarding jet penetration, volumetric growth, mixing enhancement and discharge coefficient. Additionally an artificial inlet boundary conditions was tested for the use with real-gas thermodynamics and was shown to be capable of reducing the simulation time significantly.