Ricerc@Sapienza

In spite of the quite remarkable progress achieved in incompressible flows in the past two decades, turbulence and chemistry are still one of the open problems in compressible flows. Most of the development in incompressible flows has resulted in the successful implementation of DNS and LES to realistic case studies and to the creation of a large data base of both industrial applications and experiments. In stark contrast, the physics of reactive compressible turbulent flows is very poorly understood, even though applications abound. Supersonic combustion (SC)suffers problems with
fuel and air mixing, ignition, and flame stabilization due to flow residence timescales being of same order as chemical kinetics timescales. Creating regions of lower speed flow and recirculation through modifications in geometry such as addition of cavities, or using ramp injectors, has been found to mitigate the characteristic time disparity, but lead to significant pressures losses and difficulties in thermal management. Consequently, exploration of new methods to enhance ignition and flame stabilization is critical. Plasma assisted ignition and combustion could be a promising way to
initiate and maintain combustion of ultra-lean mixtures and/or at high fluxes, to anchor the flame and to reduce pollutants. With this background, the purpose of this work is:1 to clarify the fundamental physics of SC when compressibility effects are significant identifying key mechanisms for flame anchoring and combustion stability and 2
the direct coupling effect between plasma and flame;3 to develop a detailed model for plasma assisted combustion and a turbulence/chemistry SGS model accounting for compressibility;4 to translate these models into numerical subroutines
with the aim to make available for the CFD users a full validated numerical code for SC. Progress in this field will not only improve understanding of physics but also performance and emissions of future engines and transportation systems.