Effects of Pressure and Hydrogen Enrichment with Methane in a Reacting Jet in Crossflow

The effects of hydrogen enrichment on combustion characteristics of a methane jet in crossflow are studied under elevated pressure conditions. Large Eddy Simulations (LES) are conducted for two fuel compositions −20% H 2/80% CH 4 and 40%/60% (by volume) – at 10 and 15 bar pressures to gather insights on the interplay between turbulence and chemical kinetics under these conditions. The computed velocity and hydroxyl-gradient fields agree well with measurements, indicating that the modeling framework captures the flow features well. The results suggest that hydrogen enrichment enhances local reactivity, particularly in the windward and leeward flame stabilisation regions. A 5 bar increase exhibits a similar level of influence on the chemical timescales as a 20% increase in hydrogen volume fraction. However, pressure modifies the subgrid-scale turbulence more than the hydrogen addition because of the increased crossflow and jet Reynolds numbers. The variation of flow to chemical timescale ratios along the jet centreline reveals that subgrid-scale turbulent mixing is significantly faster than chemical kinetics, whereas the large-scale turbulent mixing is much slower, irrespective of the changes in pressure or hydrogen content. However, the combustion occurs in thin reaction zone regime with due changes toward the corrugated flamelet regime when the pressure is increased.