Simulation of a Reacting Jet in Cross-Flow: detailed chemistry, molecular differential diffusion, and vorticity

The significance of a jet in cross-flow (JICF) lies in its practical applications in combustion systems, like gas turbines or industrial burners, the emission control of pollutants resulting from incomplete mixing, and its impact on aircraft engine performance for higher thrust capabilities. In this study, we simulate three distinct JICF scenarios with combustion: non-reacting (NR) and two reacting cases (R1 and R2). In the R1 case, the flame exists external to the jet shear layer, while in the R2 case, the flame resides within the jet shear layer. To achieve this, we employ our in-house reacting flow solver based on a coupling of OpenFOAM with Cantera, to investigate the impacts of detailed chemistry, mixture-averaged transport models, and vorticity structures within JICF cases. When compared to the original reactingFoam solver in OpenFOAM, our Cantera-coupled reactingFoam solver demonstrates superior performance in capturing flame structures and variations in species mass fraction on the windward side, as well as flow characteristics such as shear layer vorticity (SLV), Wake vorticity (WV), and counter-rotating vortex pairs (CVPs). Specifically, we will demonstrate the following: (i) The original reactingFoam solver, employing a single-step chemistry model, demonstrates reduced jet velocity, resulting in notably weaker shear layer vorticity (SLV) formations and the presence of narrow, high-endothermic lines. Conversely, the detailed chemistry setting portrays wider endothermic areas without a flame on the windward side. (ii) Cantera-coupled reactingFoam, using a mixture-averaged transport model, can exhibit an attached flame for R1 and R2 cases. This differs from the original solver, which uses a unity Lewis model, shows distinct windward lifted and leeward attached shapes in the R1 case. (iii) The vorticity structure analysis explores shear layer vorticity (SLV), horseshoe vorticity (HV), wave vorticity (WV), and hairpin-shaped counter-rotating vortex pairs (CVPs) concerning the effects of jet Reynolds number.