High-fidelity simulations for clean and efficient combustion of alternative fuels

Abstract

The monolithic nature of transportation technologies offers opportunities for significant improvements in efficiency of 25-50% through strategic technical investments in both advanced fuels and new low-temperature engine concepts. The application of direct numerical simulation (DNS) provides a way to study fundamental issues related to small-scale combustion processes in well-defined canonical configurations, whereas the application of large eddy simulation (LES) provides a formal treatment of the full range of time and length scales that exist in turbulent reacting flows, and thus provides a direct link to experimental studies of relevant combustion devices. In the present study, through DOE INCITE and Oak Ridge National Laboratory 250 Tflop Transition-to-Operations grants in 2008, DNS is performed to understand how a lifted autoignitive flame is stabilized, and LES is performed to understand the high-pressure injection and mixing processes in internal combustion engines. Understanding of these and other fundamental issues is needed to develop robust and reliable ignition and combustion models for the combustion regimes observed under low-temperature combustion engine environments using alternative fuels.