INITIAL NUMERICAL SIMULATIONS OF A LABORATORY-SCALE PREMIXED HYDROGEN/AIR HIGH SWIRL EXPERIMENT

As decarbonization of combustion systems is critically important, studies focusing on hydrogen combustion are required and undertaken for various future industrial applications. In this context, an experiment located at The Combustion and Propulsion for Aviation Research Center is studied with numerical simulations to get insights into both non-reacting and reacting flowfield. This article presents the computational results of a series of numerical simulations of this laboratory scale fully premixed hydrogen/air experiment. The design of the experiment is first discussed with key components of the setup being described. This setup includes water-cooled bluff-body and upstream plenum for flashback mitigation, axially translatable swirler for combustion instability passive control, and both partially-premixed and fully premixed operating conditions. The simulated operating point corresponds to an equivalence ratio of 0.6, an injector bulk velocity of 13.4 m s(-1) and a thermal power of 9 kW. The article discusses results obtained with Reynolds-Averaged-Navier-Stokes (RANS) and Large-Eddy-Simulations (LES) for the non-reacting flow as well as obtained with Stress-Blended Eddy Simulations (SBES) for the reacting flow. State-of-the-art meshing and geometry capabilities are used and lead to a poly-hexacore mesh made for those simulations with a cell count of 6.2 million. The turbulence closure, the combustion and kinetic models used along with the simulations settings are described. The convergence is discussed with two main metrics: mass conservation and residuals monitoring. The results indicate that the current experimental design enables: (i) the formation of a strong inner recirculation zone (IRZ) and an outer recirculation zone (ORZ) as captured by the computations, (ii) the stabilization of a highly swirled premixed hydrogen/air flame which is observed to be compact.