Ricerc@Sapienza

Nowadays computational fluid dynamics (CFD), due to the ever rising computing power, can be considered both a fundamental tool in basic research and a useful industrial design tool. Indeed the development cost of a combustion device can be sensibly lowered by means of numerical simulations instead of expensive experiments and tests. On the other hand, numerical simulations can help the physical investigation of combustion phenomena. Major difficulties in understanding premixed turbulent combustion are associated with turbulent burning being a highly nonlinear and multi-scale phenomenon, which locally involves various processes, such as chemical reactions, heat release and thermal expansion, molecular transport, and turbulence.
In this context, a relatively unexplored subject that has found
a growing interest is the role played by intrinsic flame instabilities, as Darrieus-Landau (DL), in the turbulent propagation of a premixed flame. Intrinsic instabilities can largely modify laminar flame propagation and can affect the interaction between turbulence and flame structure. In fact, the DL mechanism appears to play a substantial role in premixed turbulent combustion by controlling the growth of unburned mixture fingers and therefore causing oscillations of the flame surface area, turbulent burning velocity, and mean flame brush thickness. This research project focalizes on such interplay, aiming to characterize all of the main features of turbulent premixed flame propagation whenever, under equivalent laminar flow, the operative conditions would favor the onset of instabilities. As a result, reliable predictions of the burning speed based on the turbulent and thermochemical conditions ahead of the flame has been a central problem in combustion science. Turbulent premixed combustion can be studied using direct numerical simulations, taking advantage of present High Performance Computer (HPC) resources using and modifying an highly scalable open source code.