Investigating the Effect of Side Jet Dilution in a Hydrogen-Fuelled Swirl Combustor

Understanding the influence of side dilution jets on the flame behaviour is crucial for the reliable design of Rich-Quench-Lean (RQL) gas turbine combustors. This study investigates the effect of side dilution jets in a bluff body swirl-stabilised hydrogen-fuelled model gas turbine combustor using Large Eddy Simulation (LES) with Conditional Moment Closure (CMC) as the sub-grid combustion model. LES-CMC has been conducted using a detailed chemical mechanism comprising 57 species and 273 reactions that include NO formation. Reasonable agreement between the LES-CMC and the experimental data has been observed in terms of the overall flame shape for different dilution levels. Moreover, the comparison between the lower and higher side-dilution levels shows that the higher dilution case leads to a more compact flame, with reduced primary-zone mean temperatures, OH mass fractions and NO mass fractions, which is associated with stronger transverse jets promoting enhanced mixing and higher scalar dissipation rates. The results demonstrate the applicability of the applied modelling framework in the prediction of pure hydrogen combustion behaviour in a swirl RQL-like combustor configuration.