Multi-scale coupling for predictive injector simulations

Abstract

Predictive simulations of full fuel injection systems for e.g. diesel engines could be very important for reducing emissions of current engines but are still rare. Beside the numerical issues arising from discontinuities across the liquid-gas-interface, different scales relevant for the nozzle internal flow, primary breakup in the vicinity of the nozzle, and secondary breakup and evaporation further downstream make efficient simulation of the full injection system challenging. This paper introduces a multi-scale coupling approach for overcoming this issue leading to efficient and predictive injector simulations. After a brief description of the numerical methods used in this study, the coupling among nozzle internal flow, primary breakup, and secondary breakup with evaporation is introduced and analyzed with respect to computing efficiency and physical accuracy. Finally, the simulation framework is applied to the “Spray A” case of the Engine Combustion Network.