Experiment on afterburner combustion efficiency based on self-excited sweeping nozzle

To prove the feasibility of applying the self-excited sweeping nozzle in the afterburner, and the effectiveness of high frequency dynamic sweeping fuel injection methods for improving the efficiency of afterburner combustion, this study designed a fuel spray bar integrated with the self-excited sweeping nozzles, tested its basic working characteristics, such as flow rate, frequencyand sweeping angle, and further compared these characteristics with the plain-orifice spray bar. Then, based on the rectangular afterburner test rig, under the same test conditionsand the fuel-to-air ratio range, the overall combustion efficiencies are testedand the dynamic wall pressure pulsation information is monitored, employing the plain-orifice spray barand self-excited sweeping spray bar respectively. The results show that multiple self-sweeping nozzles can be integrated into the spray bar with the diameter limitation of 10mm. the flow capability of the self- excited sweeping spray bar is increased by 23%, compared to the plain-orifice spray bar with the equivalent geometric flow area. For the nozzles in the same spray bar, their operating frequencyand sweeping angle responses to the pressure drop are basically the sameand have good consistency. The afterburner combustion efficiency is improved by 3.7%, by employing the self-excited sweeping spray bar, and no dynamic pressure pulsation frequency is detected which is the same or close to the operating frequency of self-excited sweeping nozzle, indicating that high frequency dynamic sweeping fuel injection has no direct impact on the flame thermoacoustic oscillation modeand large scale shedding vortex structure downstream the flameholder.