模型预混燃烧室燃烧不稳定性研究

Investigation on combustion instability in model premixed combustor

针对钝体火焰稳定器结构的模型预混燃烧室的燃烧不稳定性现象进行了实验研究和数值模拟.实验中利用动态压力传感器测量了不同当量比时燃烧室内动态压力的频率和振幅.结果表明:随当量比增加,不稳定性频率从251Hz增加到258Hz.不稳定性振幅与大气压力比值从2.7%增加到6.1%.对燃烧室进行了定常和非定常数值模拟以及声学模态分析,得到了周期性旋涡脱落的频率为260Hz和燃烧室系统的前5阶本征声学模态频率.其中第3阶纵向声学模态频率与实验值基本一致,说明维持不稳定性的机理为钝体火焰稳定器后旋涡的周期性对称脱落和燃烧室系统的第3阶纵向声学模态形成了耦合.

Experiments and numerical simulations were conducted on combustion instability in model premixed combustor with bluff body flame holder.Pressure transducers were used to measure frequency and amplitude of the combustor dynamic pressure at different equivalence ratios.Results show that instability frequency increases from 251Hz to 258Hz with the growing equivalence ratio.The ratio between instability amplitude and atmospheric pressure increases from 2.7%to 6.1%.The periodic vortex shedding frequency of 260Hz was calculated by steady and unsteady numerical simulation.The first five combustor nature acoustic mode frequencies were obtained by acoustic mode analysis.The third longitudinal acoustic mode frequency is near the experiment value.The mechanism is the coupling between symmetric vortex shedding periodicity behind bluff body flame holder and the third longitudinal acoustic mode of the combustor.