单扇区、扇形、全环燃烧室热声不稳定性试验和模拟研究

Experimental and numerical investigation of thermo-acoustic instability in single-sector, sector and full annular combustors

贫油分级燃烧室在单扇区、扇形、全环燃烧室试验台上均会发生自激周期性燃烧不稳定现象,但振荡模态和频率存在差异。为研究这一差异并建立三者之间的联系,同时验证热声不稳定性模拟方法,对三种试验台的燃烧不稳定性进行了试验和数值模拟研究,获得了不同试验台的振荡特性,并对数值模拟和试验结果进行了对比。结果表明:全环燃烧室存在两个失稳模态,扇形燃烧室只存在一个失稳模态,单扇区燃烧室也只存在一个失稳模态;单扇区、扇形燃烧室可以反映全环燃烧室中其中一个失稳模态,而无法反映全环燃烧室的另外一个失稳模态;三维有限元热声模拟方法准确预测了三种不同试验台的燃烧稳定性,预测的无量纲失稳频率与试验结果一致,误差在2%以内。

Self-excited periodic combustion instabilities in a staged lean burn combustor could be generated by operating the combustor at single-sector,sector and full annular combustor test rigs,but differences existed in oscillation modes and frequencies.In order to investigate the differences and establish the relationship among them,and to verify the thermo-acoustic instability simulation method, experiments and numerical simulations of combustion instabilities were carried out on these three kinds of test rigs,the oscillation characteristics of different test rigs were obtained, and the results were compared between simulations and experiments. The results showed that there were two unstable modes in full annular combustor, while only one unstable mode existed in sector combustor and single-sector combustor.The single-sector and sector combustors can represent one of the unstable modes in full annular combustor,but cannot represent another unstable mode. The three-dimensional finite element method thermo-acoustic simulation method accurately predicted the combustion instabilities of these three different kinds of test rigs,and the predicted dimensionless unstable frequencies were consistent with the experimental results with an error within 2%.