The Effect of Fuel Staging on the Structure and Instability Characteristics of Swirl-Stabilized Flames in a Lean Premixed Multi-Nozzle Can Combustor
The Effect of Fuel Staging on the Structure and Instability Characteristics of Swirl-Stabilized Flames in a Lean Premixed Multi-Nozzle Can Combustor
复制标题
燃料分级对稀薄预混多喷嘴罐式燃烧器旋流稳定火焰结构及不稳定特性的影响
DOI：
10.1115/1.4037461
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发表时间：
2017
影响因子：
1.5
通讯作者：
J. O’Connor
中科院分区：
文献类型：
--
作者：
Janith Samarasinghe;Wyatt Culler;B. Quay;D. Santavicca;J. O’Connor
燃料分级是燃气涡轮发动机运行中常用的一种策略。在多喷嘴燃烧室配置中，这是通过改变不同喷嘴的燃油流量来实现的。研究了燃料分级对火焰结构和自激不稳定性的影响。在各喷嘴燃料相等且燃烧室处于自激不稳定状态的工况下，无论是通过分级提高总当量比，还是在分级时保持总当量比不变，燃料分级都成功地抑制了不稳定。增加燃料分级改变了相邻火焰相互作用区域的时间平均热释放率分布，并降低了这些区域的热释放率波动幅度。增加燃料分级也会导致单调相行为的破裂，这是沿火焰行进的对流扰动的特征。特别是，中间火焰和火焰-火焰相互作用区域的放热速率波动与外火焰的放热速率波动相异，导致全局放热速率振荡被抵消。燃烧室内的瑞利积分分布表明，在自激不稳定过程中，热释放率波动最大的区域与燃烧室压力波动呈同相变化。当引入分段燃料时，这些区域随压力波动而非相位波动，进一步说明燃料分段通过相位抵消机制抑制不稳定性。
Fuel staging is a commonly used strategy in the operation of gas turbine engines. In multinozzle combustor configurations, this is achieved by varying fuel flow rate to different nozzles. The effect of fuel staging on flame structure and self-excited instabilities is investigated in a research can combustor employing five swirl-stabilized, lean-premixed nozzles. At an operating condition where all nozzles are fueled equally and the combustor undergoes a self-excited instability, fuel staging successfully suppresses the instability: both when overall equivalence ratio is increased by staging as well as when overall equivalence ratio is kept constant while staging. Increased fuel staging changes the distribution of time-averaged heat release rate in the regions where adjacent flames interact and reduces the amplitudes of heat release rate fluctuations in those regions. Increased fuel staging also causes a breakup in the monotonic phase behavior that is characteristic of convective disturbances that travel along a flame. In particular, heat release rate fluctuations in the middle flame and flame–flame interaction region are out-of-phase with those in the outer flames, resulting in a cancelation of the global heat release rate oscillations. The Rayleigh integral distribution within the combustor shows that during a self-excited instability, the regions of highest heat release rate fluctuation are in phase-with the combustor pressure fluctuation. When staging fuel is introduced, these regions fluctuate out-of-phase with the pressure fluctuation, further illustrating that fuel staging suppresses instabilities through a phase cancelation mechanism.