Operational sensitivities of an integrated aerodynamic-ramp-injector / gas-portfire flameholder in a supersonic combustor

摘要

Results are presented of experiments conducted in a supersonic wind tunnel on an integrated fuelinjection/ignition system, consisting of an aeroramp injector and a gas-portfire igniter. The main goals of thework were to determine how the lifting effect of the gas-portfire affected the fuel from aeroramp jet, toascertain how the injection of gas through the gas-portfire influenced the combustion in the combustor model,and to investigate any synergistic effects from the combination. The gas-portfire igniter/flame holder wasplaced downstream of the injector on the centerline at three different locations in order to find the best suitablegas-portfire injector geometrical configuration. The aeroramp was observed to generate a pair of streamwisevortex and gas-portfire had a strong lifting effect on this vortex. Experiments achieved a stable combustionwhen ethylene equivalence ratio was above 0.05. As the gas-portfire momentum flux ratios were increasedfrom 0.64 to 1.43, the ignition delay time was shortened obviously while the combustion efficiency was notinfluenced. A 3-D numerical study was conducted to investigate the details of combustion flow structure. Thepressure distribution obtained by experiment and simulation agreed well (average error<5%). The numericaland experimental results show that the distance between gas-portfire and aeroramp injector is a criticalparameter which influences the combustion efficiency. The results demonstrate that the gas-portfire plays animportant role in combustion enhancement. The ignition delay time is sensitive to momentum flux ratios ofgas-portfire. When the momentum flux ratio is 0.64, the delay time reaches nearly 1s. One should note thatethylene fuel cannot be ignited when equivalence ratio was below 0.55.