Application of the Dynamic Zone Flamelet Model to High-Speed Turbulent Combustion

Scale-resolving simulations of scramjet flowpaths with detailed chemical kinetics are prohibitively expensive, which motivates the use of low-cost statistical combustion models. One recent approach that extends the Conditional Moment Closure method is the Dynamic Zone Flamelet Model (DZFM). DZFM was established to reduce the cost of scale-resolving Large Eddy Simulations with large chemical kinetic mechanisms for high-speed flows. Conditional mass fraction transport equations are solved on a dynamic coarse mesh composed of zones that are partitioned according to the streamwise coordinate and flow field values. In this study, both steady and unsteady simulations are performed with DZFM. Reynolds-Averaged Navier-Stokes (RANS) and Improved Delayed Detached-Eddy Simulation (IDDES) turbulence models are used for a hydrogen jet in supersonic crossflow test case. In addition, initial RANS results for a hydrogen-fueled scramjet combustor equipped with a flameholding cavity are presented. The temperature and H2O distributions produced by the model are compared with laminar finite-rate chemistry results, and similarities in these profiles indicate that DZFM has potential for the application of high-speed combustion. However, limitations of the model exist with the current zone partitioning. Further analysis of the laminar finite-rate chemistry results indicates that DZFM could be improved by delineating zones based on more flow field values than just the mixture fraction to more accurately represent the local chemical state in all regions of these complex flows.