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arXiv 2305.03415physics.flu-dyn
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富氢贫燃中的耦合热声相互作用

Coupled thermoacoustic interactions in hydrogen enriched lean combustion

Abhishek Kushwaha, Amitesh Roy, Ianko Chterev, Isaac Boxx, R. I. Sujith

AI总结:

本研究提出基于扩展本征正交分解的框架,研究富氢天然气旋流燃烧室中周期1、周期2热声不稳定性的多场耦合特性,揭示了不同振荡状态下的空间结构关联与锁频规律。

摘要:

本文提出了一个研究技术预混旋流火焰中流速与声压、热释放速率同步性的框架。该框架采用扩展本征正交分解(extended proper orthogonal decomposition,简称extended POD),识别速度场中速度与热释放波动高度相关的区域。我们将该框架应用于研究以富氢天然气为燃料的技术预混旋流稳定燃气轮机模型燃烧室中,与周期1型和周期2型热声不稳定性相关的耦合相互作用。通过extended POD,我们找到了与流场主导相干结构相关的火焰面和热释放速率结构。我们观察到,在周期1振荡的热声不稳定性过程中,流速、火焰面和热释放速率场中的相关结构具有相同的空间分布区域。在周期2振荡的情况下,火焰面与热释放速率场的结构强相关,但这些结构对流场相干结构的贡献较小。利用流速场主导POD模态的时间系数,我们还观察到在周期1和周期2振荡状态下,声压、热释放速率的时间序列与速度场前两个主导POD模态的时间系数之间分别存在1:1和2:1的锁频行为。这些锁频状态表征了潜在的相位同步状态,随后我们将其与流速场中的相干结构建立了关联。

英文摘要:

In this paper, we present a framework to study the synchronization of flow velocity with acoustic pressure and heat-release rate in technically-premixed swirl flames. The framework uses the extended proper orthogonal decomposition to identify regions of the velocity field where velocity and heat release fluctuations are highly correlated. We apply this framework to study coupled interactions associated with period-1 and period-2 type thermoacoustic instability in a technically-premixed, swirl stabilized gas turbine model combustor operated with hydrogen-enriched natural gas. We find the structures in flame surface and heat release rate that are correlated to the dominant coherent structures of the flow field using extended POD. We observe that the correlated structures in the flow velocity, flame surface and heat release rate fields share the same spatial regions during thermoacoustic instability with period-1 oscillations. In the case of period-2 oscillations, the structures from flame surface and heat release rate field are strongly correlated. However, these structures contribute less to the coherent structures of the flow field. Using the temporal coefficients of the dominant POD modes of the flow velocity field, we also observed 1:1 and 2:1 frequency locking behaviour among the time series of acoustic pressure, heat release rate and the temporal coefficients of the first two dominating POD modes of velocity field during the state of period-1 and period-2 oscillations, respectively. These frequency-locked states, which indicate the underlying phase-synchronization states, are then correlated with coherent structures in the flow velocity field.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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