Characterisation of hydrogen jet flames under different pressures with varying coflow oxygen concentrations

The elevated temperature of hydrogen combustion increases the formation thermal NOx. Moderate or intense low oxygen dilution (MILD) is known to reduce NOx emissions and increase efficiency. Pressure often also used for increasing impact that pressure has on fluid dynamics chemical kinetics especially relevant in MILD conditions. Hydrogen jet flames issuing into a hot vitiated coflow were imaged using OH∗ chemiluminescence at different pressures (1–7 bar) levels (3–9% by vol.). Laminar flame simulations complemented experiments. observed mean radial width increased with pressure, but only O2 content less than 9%, suggesting greater influence when reduced. integrated signal strength remained constant 3% O2, despite an apparent width, spatial broadening pressure. Numerical results indicate 3–6% conditions H2 are met across wide range strains pressures, supporting experimental observations O2.