Large Eddy Simulation of a Turbulent Reacting Compressible Jet

We report results of a Large Eddy Simulation (LES) effort of turbulent compressible nonpremixed reactive jets. It is well known that there are several difficulties associated with compressible reactive flows in comparison with incompressible flows. In incompressible flows, the energy and mass conservation (for constant density flows) equations are decoupled from the velocity field. Moreover, the subgrid terms that are required in these flows need only provide with the deviatoric part of the subgrid contributions. The isotropic part can be absorbed in the pressure term. In reacting incompressible flows, one can also avoid the need to integrate the conservation equations for mass and energy by using a conserved scalar approach. In this case, both temperature and density are determined from a state relationship that is known beforehand. On the other hand, for compressible reacting flows one is not allowed to discard the energy and mass conservation equation since acoustics and in some cases shocks coexist with heat release. In the present investigation we use the totally conservative formulation in terms of total sensible energy. Other forms of the energy equation require closure for pressure velocity correlations, [1]. This is not requited in the total sensible energy form, although some other correlations are needed, notably, those between enthalpy and mass fractions of species. Furthermore, we are interested in using local subgrid models. The advantages of this kind of approach are self evident, specially in complex geometries. The results discussed in this abstract are obtained with the stretched vortex model for turbulent transport [2], scalar transport [4] and subgrid scalar variance [3]. Here, we consider a model problem of a turbulent planar nonpremixed reacting jet. The modeling assumptions are described next, followed by some preliminary results.