An investigation of bi-directional flame-acoustic interactions during thermoacoustic instabilities

热声不稳定性期间双向火焰声相互作用的研究

• 批准号: 2053671
• 负责人: Abhishek Saha
• 金额: $ 30.43万
• 依托单位: University of California-San Diego
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2021
• 资助国家: 美国
• 起止时间: 2021-05-01 至 2024-12-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2053671&HistoricalAwards=false
• 关键词: investigation; bi; directional; flame; acoustic

Gas turbines used for power generation and propulsion can experience large pressure fluctuations as a result of thermoacoustic instabilities. These instabilities arise from the interaction of sound and heat release within the engine combustion chamber and represent a major challenge for safe and reliable operation of the engine. The frequent occurrence of thermoacoustic instabilities can limit the performance and the lifetime of gas turbine combustors, particularly when running under conditions designed to reduce emissions and fuel consumption. However, due to complex processes including chemical reactions, turbulent flow, heat release, and acoustic, a detailed simulation of thermoacoustic instabilities remains challenging and computationally expensive. The proposed project aims to develop a simpler mathematical model that can predict and capture the transition from stable to unstable behavior in combustors. Experiments will be carried out to assess the model's performance and to provide benchmark data for validating models developed by other researchers. The outcome of the study will enable engine designers to predict and mitigate thermoacoustic instabilities and improve reliability and performance. As a broader impact of the work, undergraduate and graduate students, particularly from underrepresented minority groups, will gain experience in using advanced experimental and modeling tools.The program proposes to develop a synchronization-based framework to design low order models capable of capturing the dynamic transitional behaviors in turbulent combustors during thermoacoustic instabilities. The study, which synergistically includes modeling and experimental components, will facilitate the development of improved predictive tools to provide better control strategies in mitigating prevalent thermoacoustic instabilities. In modeling, the primary objective is to introduce a system of two mutually coupled oscillators, representing the flame and acoustics, to capture the bi-directional nature of the feedback in thermoacoustic instability. Such a model will capture three dynamical states, periodic, intermittent, and chaotic, observed in practical systems, hence overcome the shortcoming of unidirectionally coupled models, such as FTFs and FDFs. Furthermore, the program will develop experimental strategies, where the two-way coupled systems can be simulated by perturbing a flame with acoustic forcing whose frequency and amplitude are modulated based on the ensuing flame dynamics. The experiments will enable us to observe the differences in local and global flame dynamics when perturbed with coupled or de-coupled acoustic forcing and to gather data for model validation.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.

由于热声不稳定性，用于发电和推进的燃气轮机可以经历较大的压力波动。这些不稳定性是由发动机燃烧室内声音和热量释放的相互作用引起的，对发动机的安全可靠运行构成了重大挑战。频繁发生的热声不稳定性会限制燃气轮机燃烧器的性能和使用寿命，特别是在旨在减少排放和燃料消耗的条件下运行时。然而，由于包括化学反应、湍流、热释放和声学在内的复杂过程，热声不稳定性的详细模拟仍然具有挑战性，并且计算成本很高。拟议的项目旨在开发一个更简单的数学模型，可以预测和捕捉燃烧器从稳定到不稳定行为的转变。将进行实验以评估模型的性能，并为验证其他研究人员开发的模型提供基准数据。该研究结果将使发动机设计人员能够预测和减轻热声不稳定性，提高可靠性和性能。由于这项工作的广泛影响，本科生和研究生，特别是来自代表性不足的少数群体的学生，将获得使用先进实验和建模工具的经验。该计划建议开发一个基于同步的框架来设计低阶模型，该模型能够捕获热声不稳定期间湍流燃烧室中的动态过渡行为。该研究协同包括建模和实验组件，将促进改进预测工具的开发，以提供更好的控制策略，以减轻普遍存在的热声不稳定性。在建模中，主要目标是引入一个由两个相互耦合的振荡器组成的系统，代表火焰和声学，以捕捉热声不稳定性反馈的双向性质。该模型将捕获实际系统中观察到的周期、间歇和混沌三种动态状态，从而克服了单向耦合模型（如FTFs和fdf）的缺点。此外，该计划将开发实验策略，其中双向耦合系统可以通过用声波强迫干扰火焰来模拟，其频率和振幅是基于随后的火焰动力学调制的。实验将使我们能够观察到在耦合或解耦合声强迫扰动下局部和全局火焰动力学的差异，并为模型验证收集数据。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

项目成果

Transition to Limit-Cycle Oscillation in Fluid-Structure Interactions: Mutual Correlations and Causal Dependencies

• DOI: 10.2514/1.j062082
• 发表时间: 2022-12
• 期刊: AIAA Journal
• 影响因子: 2.5
• 作者: Sombuddha Bagchi;Vishnu R Unni;A. Saha

Regime and morphology of polyhedral bunsen flames

• DOI: 10.1016/j.combustflame.2022.112585
• 发表时间: 2023-02
• 期刊: Combustion and Flame
• 影响因子: 4.4
• 作者: Yue Weng;Aditya Potnis;Abhishek Saha

Synchronization-based model for turbulent thermoacoustic systems

• DOI: 10.1007/s11071-023-08368-z
• 发表时间: 2022-06
• 期刊: Nonlinear Dynamics
• 影响因子: 5.6
• 作者: Yue Weng;Vishnu R Unni;R. Sujith;A. Saha