火焰定位在波发生器区域对抑制湍流部分预混甲烷火焰燃烧不稳定性的作用
Role of flame localization in wavemaker regions on the suppression of combustion instability in turbulent partially-premixed methane flames
- RWTH Aachen University（亚琛工业大学）
机构由 AI 辅助整理，请以论文原文为准。
AI总结：
本研究通过实验和线性稳定性分析，证实火焰与波发生器区域的空间重叠是旋流稳定燃烧室稳定性的关键，为低排放燃烧系统设计提供指导。
AI中文摘要：
火焰动力学与流体动力学不稳定性之间的相互作用在决定旋流稳定燃烧室的稳定性方面起着根本性作用。在本研究中，我们探究了一个假设，即在具有波发生器区域的流动中，火焰与波发生器区域的空间重叠是燃烧稳定性的必要前提。为验证该假设，通过位于旋流稳定燃烧器中心体上的周向孔引入了低动量二次甲烷喷射。喷射速度保持在体积流量的5%以下，以最小化动量引起的流场修改，同时选择性地重新分配热量释放。此外，等量的燃料从主燃料供应中转移到二次喷射端口，称为燃料分级，以隔离火焰重新定位的影响与总燃料流率的影响。二次喷射的引入导致火焰从M形结构转变为V形结构，而燃料分级产生了类似的火焰响应，表明观察到的行为主要源于热量释放的重新分配。线性稳定性分析揭示，波发生器区域保持在燃烧室入口附近。此外，火焰根部从提升的M形火焰转变为附着的V形火焰，并始终稳定在与所识别的波发生器区域对应的径向位置。在稳定运行条件下，火焰附着与波发生器位置的重合提供了强有力的实验证据，表明火焰稳定由它们的空间重叠控制，而不是由潜在流体动力学不稳定性的修改控制。所提出的框架为火焰稳定与流体动力学不稳定性之间的耦合提供了新的见解，并为设计稳定、低排放的燃烧系统提供了实用指导。
英文摘要：
The interaction between flame dynamics & hydrodynamic instabilities plays a fundamental role in determining the stability of swirl-stabilized combustors. In the present study, we investigate the hypothesis that spatial overlap between flame & wavemaker region is a necessary prerequisite for combustion stability in flows characterized by a wavemaker region. To test the hypothesis, a low-momentum secondary methane injection was introduced through circumferential holes located on the centerbody of a swirl-stabilized burner. The injection velocity was maintained below 5\% of bulk flow velocity to minimize momentum-induced modifications of flow field while selectively redistributing heat release. In addition, an equivalent amount of fuel was diverted from primary fuel supply to secondary injection ports, known as fuel-staging, to isolate the effects of flame relocation from those of the total fuel flow rate. The introduction of secondary injection produced a transition of the flame from M-shaped to V-shaped structure, while fuel-staging yielded a similar flame response, demonstrating that observed behavior results primarily from redistribution of heat release. Linear stability analysis revealed that wavemaker region remains near inlet of the combustion chamber. Moreover, flame root transitions from a lifted M-flame to attached V-flame and consistently stabilizes at radial position corresponding to the identified wavemaker region. The coincidence of flame attachment & wavemaker location under stable operating conditions provides strong experimental evidence that flame stabilization is governed by their spatial overlap rather than by a modification of the underlying hydrodynamic instability. The proposed framework provides new insight into the coupling between flame stabilization & hydrodynamic instability & offers practical guidance for the design of stable, low-emission combustion systems.
