Flame Lifting of a Reacting Jet in Crossflow at Elevated Pressure Conditions

The extent of flame lifting in reacting jets in crossflow (RJICF) has a critical influence on numerous fluid mechanic and combustion features. In particular, flame lifting profoundly influences the nearfield shear layer instability development, as well as the equivalence ratio of the mixture entering the flame. The latter feature is known to have a fundamental influence on NOx emissions. This work experimentally characterizes the lifting behavior of pure fuel jets, comprised of natural gas, hydrogen, or a blend of the two, injected normally into a crossflow stream of vitiated oxygen content at elevated temperature and pressure conditions relevant to gas turbines. Of specific significance, the investigated pressures range from 5 to 20 atm. Line-of-sight OH* chemiluminescence images of the reaction zone are captured as conditions of the RJICF system are systematically varied. Using these measurements, lifting behavior is then framed against calculated autoignition delay times for the most reactive mixture fraction of crossflow and jet fuel. The results define boundaries of flame lifting based on operating conditions and, for the lifted cases, a relationship for lift-off height including pressure effects.