A Dynamic Thickening Strategy for High-Fidelity Computational Fluid Dynamics Analyses of Multi-Regime Combustion

In this study, a dynamic thickening strategy for dynamic thickened flame model for large eddy simulations (DTFLES) application to multi-regime combustion is proposed. The main idea lies in using the numerical solution of an ordinary differential equation (ODE) as a thickening factor. The equation relates the time derivative of the local thickening factor to its production and destruction rates, which are proportional to the gap between the instantaneous value and optimal target values. The smoothness of the thickening factor in time is ensured by the ODE solution, while in space it is achieved through a mathematical function defined in a continuous flame index space. The equation is numerically integrated with a semi-implicit scheme by making use of the backward Euler formula. The strategy has been implemented in a commercial computational fluid dynamics (CFD) solver and it has been tested by performing Large Eddy Simulations of the hydrogen/air flame produced by the HYLON injector, which has been individuated as an interesting test case for the proposed dynamic strategy. Turbulence-chemistry interactions are recovered by means of a well-assessed subgrid efficiency model. Numerical results are compared with the experimental ones obtained at Institut de Mécanique des Fluides de Toulouse (IMFT).