为了在实际应用条件约束下,进一步验证自激扫掠喷嘴改善加力燃烧性能的有效性,本研究首先设计了含有10个自激扫掠喷嘴的加力燃油喷杆,以及喷孔数量、喷点位置、喷孔总流量数均一致的直射式喷杆,并对其流量、频率、张角等基本工作特性进行了测量和对比分析。然后,在典型涡扇发动机外涵的高速中温气流工况下,基于矩形加力燃烧性能测试平台,分别采用直射喷杆和自激扫掠喷杆,测量出口截面的总体燃烧效率,并监测沿程的温度分布,以及壁面动态压力脉动信息。结果表明,与直射式喷杆相比,采用自激扫掠喷杆能够显著拓宽燃烧室的点熄火边界,并在全油气比范围内提高燃烧效率,最高改善了8.5%,沿程燃气温度最高提高了181℃。在较高当量比下,采用直射式喷杆时,激发出了140Hz左右的低频纵向热声耦合振荡燃烧频率,压力相对振幅达到16.3%;而在相同工况下,采用自激扫掠喷杆时的压力相对振幅仅为2.3%,有效抑制了振荡燃烧的发生。本研究充分证明了自激扫掠喷嘴在提高加力燃烧效率,拓展稳定燃烧边界,以及调控加力振荡燃烧方面的显著效果。
In order to further prove the effectiveness of self-excited sweeping nozzles in enhancing afterburner combustion performances under the constraints of practical application conditions, this study first designed an afterburner fuel spray bar containing 10 self-excited sweeping nozzles, and a plain-orifice spray bar was also designed for comparison with the same nozzle number, injection locations, and total flow rate. The flow rate, frequency, and injection angle of both spray bars were measured and analyzed. Then, under the typical bypass airflow conditions of a turbofan engine with an airflow of high speed and medium temperature, com-bustion efficiency at the exit cross-section, temperature distribution along the path, and dynamic wall pressure fluctuations were measured using on a rectangular afterburner combustion performance test bench with the plain-orifice and self-excited sweeping spray bars respectively. The results showed that the self-excited sweeping spray bar significantly expanded the blowout limit of the combustion chamber compared to the plain-orifice spray bar, and improved combustion efficiency across the entire fuel-to-air equivalence ratio range, with a maximum improvement of 8.5%, and the gas temperature along the path increased by up to 181 ℃. At a higher equivalence ratio, the plain-orifice spray bar induced a low-frequency longitudinal thermoacoustic coupling oscillation at around 140 Hz, with a pressure relative pulsation amplitude of 16.3%. In contrast, under the same conditions, the self-excited sweeping spray bar reduced the pressure relative pulsation amplitude to only 2.3%, effectively suppressing combus-tion instability. This study fully demonstrates the notable results of self-excited sweeping nozzles in improving combustion effi-ciency, expanding the blowout limit and suppressing combustion instability of the afterburner.