Experimental studies are conducted to find an optimum size of the cavity flameholder, which is a new combustion concept of a turbine-based combined-cycle (TBCC) engine with an excellent flame stabilization. Besides, the effect of inlet pressure on the subatmospheric performance is investigated. The experimental results indicate that the increase of the cavity length improves the flame stability with an enlarged fuel/air mixture residence time, which suggests that the big length-height ratio in a proper range of the cavity with a stable dual-vortex should be chosen when designing the cavity-based combustor. In addition, the decrease in lean ignition and the lean blowout equivalence ratios can be attributed by either increase in the inlet pressure and temperature or decrease in the Mach number. The increase in inlet pressure will lead to a linear decrease in the lean blowout equivalence ratio with a slope of 0.66 per 0.1 MPa, whereas the lean ignition equivalence ratio has a rapid drop with the increase of pressure from 0.06 MPa to 0.08 MPa and reduces slowly with the growth of pressure in the range of 0.08 MPa to 0.1 MPa. The detailed analysis of the flow field indicates that the characteristic time-scale theory can ideally explain and predict the change of flame stability in the trapped vortex cavity.

中文翻译：

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进气压力对基于腔型燃烧室的最佳尺寸下的大气压火焰稳定的影响

进行了实验研究，以找到型腔火焰保持器的最佳尺寸，这是具有出色火焰稳定性的基于涡轮的联合循环（TBCC）发动机的新燃烧概念。此外，研究了进气压力对低于大气压性能的影响。实验结果表明，腔长的增加可改善火焰稳定性，同时延长燃料/空气混合物的停留时间，这表明在适当的腔内，应选择具有稳定双涡旋的较大的长高比。在设计基于腔的燃烧器时。此外，稀薄点火的减少和稀薄吹出当量比的降低可归因于入口压力和温度的升高或马赫数的降低。入口压力的增加将导致稀燃喷射当量比线性下降，斜率每0.1 MPa为0.66，而稀薄点火当量比随着压力从0.06 MPa升高到0.08 MPa而迅速下降，并缓慢降低压力的增长范围为0.08 MPa至0.1 MPa。对流场的详细分析表明，特征时标理论可以理想地解释和预测截留涡腔内火焰稳定性的变化。