基于先锋氢点火和双凹腔火焰稳定的煤油超声速燃烧特性

采用先锋氢火焰点火方式和串联双凹腔火焰稳定机制,开展了模拟飞行马赫数4.0纯净空气条件下液态煤油燃料超声速点火、火焰稳定和燃烧特性的试验研究。典型的燃烧室进口来流状态为马赫数2.0,总温约815K,总压700～800kPa。试验中上游凹腔采用喷油/点火一体化设计并几何结构保持恒定,分别研究了下游凹腔深度10mm,12.5mm和15mm时对煤油超声速点火、火焰稳定和燃烧特性的影响;此外,通过串联双凹腔沿轴向后移及间距拉大,研究了其对煤油超声速燃烧特性的影响。试验结果表明:(1)采用先锋氢辅以火花塞点火方式可以可靠实现煤油燃料超声速点火,并最终实现自持稳定燃烧。(2)下游凹腔起到了很好的火焰稳定器作用,增大凹腔深度可以有效地增强火焰稳定性能,同时扩展火焰稳定的油气比范围。(3)双凹腔后移使得主燃烧区向下游移动,在相同油气比条件下有效缓解燃烧诱导压升对上游隔离段的扰动。

Supersonic Combustion Characteristics of Liquid Kerosene Under Pilot Hydrogen Ignition and Dual-Cavity Flameholding Condition

With the pilot hydrogen ignition and tandem dual-cavity flameholding mechanism,the liquid kerosene-fueled supersonic ignition,flame stabilization and combustion characteristics were experimentally investigaed using direct-connected test facility of Northwestern Polytechnical University.The typical flow conditions at combustor entrance are: Ma=2.0,total-temperature Tt≈815K and total-pressure pt=700~800kPa,which correspond to a Mach 4.0 flight condition.During the experiments,the upstream cavity is functioned as a integrated injector/ignitor device with geometry invariable.The liquid kerosene and gas hydrogen were injected perpendicularly from the front and base of cavity,respectively.Effects of the downstream cavity depth on the supersonic ignition,flame stabilization and combustion characteristics of liquid kerosene were examined.Additionally,the combustion characteristics of kerosene-fueled combustor,with the dual-cavity transferred downstream and larger spacing,was examined.The results from the experimental efforts indicated that:(1) the liquid kerosene was successfully ignited and sustained combustion in the supersonic airstream with pilot hydrogen flame and tandem dual-cavity configuration.(2) the downstream cavity was functioned as a definitive flameholder,and the depth increasing can enhance flameholding and extend its fuel-air ratio range.(3) with the dual-cavity transferred downstream,the main combustion region is also moved downstream,which can effectively relax the upstream propagation of combustion induced pressure rise.