超声速燃烧室煤油多点喷注实验研究

Experimental Study of Kerosene Injection with Multi-Location in a Supersonic Combustor

关键词:  超声速燃烧室  喷注位置匹配  煤油分布  推力收益

Key words:  Supersonic combustor  Multi-location injection  Kerosene distribution  Thrust benefit

摘要:

为了解决超声速燃烧室内局部煤油当量油气比过高造成的点火及稳定燃烧困难，在Ma=5，总当量油气比接近的条件下，研究了不同煤油喷注位置相互匹配方法对发动机点火性能和推力性能的影响。研究结果表明:多个油位匹配喷注，有利于煤油点火及燃烧，发动机推力性能更好。“值班火焰”引燃煤油时，其余煤油由更多位置喷注且单个位置当量油气比更低时更容易点火燃烧。“值班火焰”的当量油气比由0.51增加到0.55时，煤油燃烧性能变差，比冲降低46N·s/kg；当量油气比均为0.51时，其余煤油由三个位置喷注比两个位置喷注时比冲增加66N·s/kg。同一截面内上部壁面喷注结合下部支杆喷注，可以优化煤油在燃烧室高度方向上的分布，获得更好的发动机性能。上游位置喷注对煤油的预混作用不明显，煤油未燃烧会造成“值班火焰”当量油气比升高，导致发动机点火性能和推力性能变差。

Abstract:

In order to solve the problems of ignition and flame-holding in some zones of a supersonic combustor where the fuel is too rich，experimental researches of different multi-location injections and their influences on the combustion/engine performances are studied under free stream Mach number 5 and with nearly the same total kerosene/air ratio. Some conclusions can be drawn: Multi-location injections are beneficial to the ignition and combustion of the kerosene and can result in better thrust performance. Combustions become much easier for cases with piloted flame and injection of kerosene from other locations with lower fuel/air ratio for a single injection location. The kerosene’s combustion performance becomes worse and the thrust specific decreases 46N·s/kg if the fuel/air ratio of piloted flame increased from 0.51 to 0.55. When the fuel/air ratio of piloted flame is 0.51 and the remainder kerosene is injected from three injection locations，the thrust specific increases 66N·s/kg，compared with the case which kerosene is injected from two injection locations. In the same section，kerosene injection from pylons on bottom wall combined with wall injection on top wall can enhance the kerosene distribution well-proportioned along the combustor height and get better thrust performance. Upstream injections do not premix kerosene well with the main flow. If ignition fails，the fuel/air ratio of piloted flame will increase，which will restrain the ignition of kerosene injected from other injectors and result in worse thrust performance.