Abstract: Through strict comparison tests in the clean and H2O/CO₂ vitiated air，the effects of H2O and CO₂ species on fuel ignition，flame stability，stable combustion performance and combustion mode in the kerosene-fueled dual-mode supersonic combustor were studied. The tests were carried out in the direct-connected scramjet facilities based on the clean air resistance heater. The conclusions are as follows. (1)The kerosene fuel ignition is restrained by the presence of H2O in the vitiated airstream. When the content of H2O is above 11%，reliable ignition cannot be achieved. (2)Compared with the clean airstream，the flame stability is reduced in the vitiated airstream. CO₂ has more influence on the flame stability than H2O of same mole fraction. (3)At fuel-off state，the wall pressure distribution along the flow direction in the vitiated air almost coincides with the clean air and there are little differences partly. (4)Both H2O and CO₂ have a certain inhibitory effect on the combustion. The wall pressure in the vitiated air is lower than the clean air and this drop of pressure，which is up to 12%，increases with the rising of vitiation levels. Moreover，CO₂ also has a greater impact on wall pressure drop than H2O of same mole fraction. (5)The vitiation changes the mode transition point of the combustor. Supposing the combustor working at the scramjet mode in the clean airstream，it will transit to ramjet mode in the high level vitiated airstream with the same fuel gas equivalent ratio likely.

Key words: Vitiation effects；Scramjet；Kerosene fuel；Dual mode；Experimental

摘要： 在以电阻加热直连式试验系统为基础的污染对比试验平台上，通过纯净空气来流和H2O/CO₂污染空气来流严格对比试验，研究了H2O/CO₂污染对煤油燃料双模态超声速燃烧室点火、火焰稳定及稳定燃烧性能等的影响。研究发现，(1)H2O污染对煤油燃料超声速燃烧室点火具有一定的抑制作用，当H2O污染含量达到11%以上时不能实现可靠点火。(2)污染组分的存在会降低燃烧室的火焰稳定性，CO₂污染对火焰稳定性的影响比相同含量H2O污染显著。(3)对于燃烧室无反应流动，纯净空气来流和污染空气来流时燃烧室壁面压力在一定范围内基本重合，仅局部存在微小差异。(4)污染组分的存在对煤油燃料超声速燃烧具有抑制作用，燃烧室壁面压力低于纯净空气试验，压力下降程度随污染水平升高而增大，最高达12%，CO₂污染对煤油燃料超声速燃烧的抑制作用比相同含量H2O污染显著。(5)污染组分的存在会导致燃烧室模态转换点发生变化，在较高的污染水平下，燃烧室的工作模态将会从相同油气比纯净空气来流下的亚燃模态转换为超燃模态。

关键词: 污染效应；超燃冲压发动机；煤油燃料；双模态；试验