污染空气对氢燃料超声速燃烧室性能的影响

Experimental investigation for vitiated air effects on hydrogen-fueled supersonic combustor performance

关键词:  污染空气  超音速燃烧  电阻加热  试验研究

Key words:  Vitiation air  Supersonic combustion  Resistance heating  Experimental investigation

摘要:

采用纯净空气和污染空气来流下对比试验的方法,研究了飞行马赫数4条件下H2O和CO2污染组分对氢燃料超声速燃烧室性能的影响。对比试验中针对纯净空气来流和污染空气来流匹配了来流总温、总压、氧气摩尔分数和当量油气比。完成了0.53和0.42两种当量油气比条件下纯净空气来流和污染空气来流的氢燃料超声速燃烧试验,预定考察的H2O污染组分摩尔浓度分别有7.5%,18%和26%三种,CO2污染组分浓度有3.0%和7.5%两种。研究结果表明,H2O,CO2或H2O+CO2组合污染对燃烧诱导压升产生了明显的非线性抑制影响,直接将污染试验空气来流下的试验结果外推应用到飞行条件,可能导致供油量偏大、甚至进气道不启动;同时也影响了隔离段内燃烧诱导激波链结构,使燃烧工作模态趋向于超燃模态。

Abstract:

By comparative study for supersonic combustion experiments both in clean airstream and vitiation airstream,typically simulating the combustor entrance condition of Mach 4 flight,individual and combined influence of H2O and CO2 vitiation on hydrogen-fueled supersonic combustor performance was investigated.The total temperature,total pressure,oxygen mole fraction and fuel equivalence ratio are matched between the test runs with clean airstream and vitiation airstream.Hydrogen fueled combustion experiments were conducted in clean air and vitiation air of various levels,under two equivalence ratios of 0.53 and 0.42,respectively.The H2O vitiation levels examined were expected to be 7.5%,18% and 26%,respectively.The CO2 vitiation levels examined were expected to be 3.0% and 7.5% respectively.The experimental results suggest that the combustion induced pressure rise can be significantly inhibited by H2O and/or CO2 vitiation.The direct extrapolation of vitiated test results to flight condition may possibly result in overfueling combustion,even inlet unstart.The H2O and/or CO2 vitiation also influence the shock waves in the isolator,resulting in the tendency of supersonic combustion mode.